Growth hormone-releasing hormone combined with arginine or growth hormone secretagogues for the diagnosis of growth hormone deficiency in adults

Growth Hormone Response to L-Arginine Alone and Combined with Different Doses of Growth Hormone-Releasing Hormone: A Systematic Review and Meta-Analysis

BACKGROUND

Arginine (ARG) can modulate growth hormone (GH) release by suppressing its endogenous inhibitory regulator, somatostatin. ARG also induces the release of the GH-releasing hormone (GHRH). This study aims to review the effects of L-arginine supplementation alone and combined with GHRH in different doses on GH secretion.

METHODS

In this systematic review and meta-analysis, an electronic literature search was conducted on Medline database (PubMed), Scopus, and Web of Science databases. All eligible studies were randomized clinical trials that reported the effects of ARG supplementation alone or with GHRH on GH levels. Mean difference (MD) and 95% confidence intervals (CI) were computed as the effect size.

RESULTS

Meta-analyses showed significant effects of ARG alone on GH release (MD = 10.07, 95% CI: 7.87, 12.28). Moreover, the response of GH was greater with ARG in combination with GHRH (MD = 24.96, 95% CI: 17.51, 32.42). There was no significant difference between the patients and healthy individuals and between oral and injection use of ARG. The systematic review revealed the important role of ARG in combination with other amino acids on GH secretion in patients with GH deficiency.

CONCLUSION

This study revealed that in GH-deficient individuals, high doses of ARG supplementation in combination with GHRH and/or other amino acids might have potential therapeutic effects on increasing GH concentrations. These findings propose that ARG supplementation can be considered as a potential stimulator in management of GH deficiency.

[Current aspects of diagnosis and treatment of adult GH-deficiency]

Adult growth hormone (GH) deficiency (AGHD) is a condition characterized by alterations in body composition, lipid and carbohydrate metabolism, bone mineral density and poor quality of life; however, clinical presentations of AGHD are mostly non-specific. Untreated AGHD is associated with increased cardiovascular morbidity and mortality. Stimulation tests are used for the diagnosis: insulin tolerance test, glucagon stimulation test, growth-hormone releasing hormone and arginine stimulation test. Moreover, in 2017 FDA approved the use of macimorelin (oral GH secretagogue) for the diagnosis of AGHD. In childhood GH-deficiency, apolipoprotein A-IV, CFHR4 (complement factor H-related protein 4) and PBP (platelet basic protein) were identified as potential biomarkers of the disease, however, this was not investigated in AGHD. GH treatment starts from the minimal dose, which allows minimizing the adverse effects. According to published meta-analyses, AGHD treatment generally does not lead to increased risk of malignancy and recurrence of sellar neoplasms in adult patients. Published data on GH receptor polymorphism associations with treatment efficacy remains controversial. Development of long-acting GH formulations is a currect perspective for the increase of treatment compliance.

Soy protein improves tibial whole-bone and tissue-level biomechanical properties in ovariectomized and ovary-intact, low-fit female rats

BACKGROUND

Osteoporosis and related fractures, decreased physical activity, and metabolic dysfunction are serious health concerns for postmenopausal women. Soy protein might counter the negative effects of menopause on bone and metabolic health due to the additive or synergistic effects of its bioactive components.

OBJECTIVE

To evaluate the effects of ovariectomy (OVX) and a soy-protein diet (SOY) on bone outcomes in female, low-capacity running (LCR) rats selectively bred for low aerobic fitness as a model of menopause.

METHODS

At 27 weeks of age, LCR rats (N = 40) underwent OVX or sham (SHAM) surgery and were randomized to one of two isocaloric and isonitrogenous plant-protein-based dietary treatments: 1) soy-protein (SOY; soybean meal); or, 2) control (CON, corn-gluten meal), resulting in four treatment groups. During the 30-week dietary intervention, animals were provided ad libitum access to food and water; body weight and food intake were measured weekly. At completion of the 30-week intervention, body composition was measured using EchoMRI; animals were fasted overnight, euthanized, and blood and hindlimbs collected. Plasma markers of bone formation (osteocalcin, OC; N-terminal propeptide of type I procollagen, P1NP) and resorption (tartrate-resistant acid phosphatase, TRAP5b; C-terminal telopeptide of type I collagen, CTx) were measured using ELISA. Tibial trabecular microarchitecture and cortical geometry were evaluated using μCT; and torsional loading to failure was used to assess cortical biomechanical properties. Advanced glycation end-product (AGE) content of the femur was measured using a fluorimetric assay, and was expressed relative to collagen content measured by a colorimetric OH-proline assay. Two-factor ANOVA or ANOVCA was used to test for significant main and interactive effects of ovarian status (OV STAT: OVX vs. SHAM) and DIET (SOY vs. CON); final body weight was included as a covariate for body-weight-dependent cortical geometry and biomechanical properties.

RESULTS

OVX had significantly greater CTx than SHAM; SOY did not affect bone turnover markers. OVX adversely affected trabecular microarchitecture as evidenced by reduced BV/TV, trabecular thickness (Tb.Th), trabecular number (Tb.N), and connectivity density (Conn.D), and by increased trabecular separation (Tb.Sp) and structural model index (SMI). SOY increased BV/TV only in ovary-intact animals. There was no effect of OVX or SOY on tibial cortical geometry. In SHAM and OVX rats, SOY significantly improved whole-bone strength and stiffness; SOY also increased tissue-level stiffness and tended to increase tissue-level strength (p = 0.067). There was no effect of OVX or SOY on AGE content.

CONCLUSION

Soy protein improved cortical bone biomechanical properties in female low-fit rats, regardless of ovarian hormone status.

Anthropometric factors have significant influence on the outcome of the GHRH-arginine test: establishment of normative data for an automated immunoassay specifically measuring 22 kDa human growth hormone

CONTEXT

Adult growth hormone (GH) deficiency (GHD) is diagnosed by provocative testing of GH secretion.

OBJECTIVE

To improve the diagnostic accuracy of GH-releasing hormone (GHRH) plus arginine (GARG) testing, we evaluated the influence of age, BMI and sex and established normative data for an automatic immunoassay specifically measuring 22 kDa human GH.

DESIGN/SETTING

Prospective multicenter study.

PARTICIPANTS

Eighty-seven patients with hypothalamic-pituitary disease and 200 healthy controls. Patients were classified according to the number of pituitary hormone deficiencies (PHD). GHD was assumed when ≥2 PHD (in addition to GH) were present (n = 51); 36 patients with <2 PHD were considered GH sufficient (GHS). ROC analysis identified cutoffs with ≥95% specificity for GHD. Controls were prospectively stratified for sex, age and BMI.

INTERVENTIONS

All participants received GHRH and l-arginine.

MAIN OUTCOME MEASURES

GH was measured by immunoassay (iSYS, IDS).

RESULTS

In controls, multiple stepwise regression analysis showed that BMI (21%, P < 0.0001), sex (20%, P < 0.0001) and age (5%, P < 0.001), accounted for 46% of GH peak level variability during GARG. Comparison of peak GH during GARG (GHD vs GHS + controls) revealed an overall cutoff of 3.9 ng/mL (sensitivity 86%, specificity 95%). After adjustment for BMI and sex, optimal cutoffs (male vs female) were 6.5 vs 9.7 ng/mL in lean, 3.5 vs 8.5 ng/mL in overweight and 2.2 vs 4.4 ng/mL in obese subjects respectively.

CONCLUSION

BMI and sex account for most of the variability of peak GH levels during GARG. Consequently, diagnostic accuracy of the GARG test is significantly improved by use of adjusted cutoffs.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY DISEASE STATE CLINICAL REVIEW: UPDATE ON GROWTH HORMONE STIMULATION TESTING AND PROPOSED REVISED CUT-POINT FOR THE GLUCAGON STIMULATION TEST IN THE DIAGNOSIS OF ADULT GROWTH HORMONE DEFICIENCY

OBJECTIVE

The clinical features of adult GH deficiency (GHD) are nonspecific, and GH stimulation testing is often required to confirm the diagnosis. However, diagnosing adult GHD can be challenging due to the episodic and pulsatile GH secretion, concurrently modified by age, gender, and body mass index (BMI).

METHODS

PubMed searches were conducted to identify published data since 2009 on GH stimulation tests used to diagnose adult GHD. Relevant articles in English language were identified and considered for inclusion in the present document.

RESULTS

Testing for confirmation of adult GHD should only be considered if there is a high pretest probability, and the intent to treat if the diagnosis is confirmed. The insulin tolerance test (ITT) and glucagon stimulation test (GST) are the two main tests used in the United States. While the ITT has been accepted as the gold-standard test, its safety concerns hamper wider use. Previously, the GH-releasing hormone-arginine test, and more recently the GST, are accepted alternatives to the ITT. However, several recent studies have questioned the diagnostic accuracy of the GST when the GH cut-point of 3 μg/L is used and have suggested that a lower GH cut-point of 1 μg/L improved the sensitivity and specificity of this test in overweight/obese patients and in those with glucose intolerance.

CONCLUSION

Until a potent, safe, and reliable test becomes available, the GST should remain as the alternative to the ITT in the United States. In order to reduce over-diagnosing adult GHD in overweight/obese patients with the GST, we propose utilizing a lower GH cut-point of 1 μg/L in these subjects. However, this lower GH cut-point still needs further evaluation for diagnostic accuracy in larger patient populations with varying BMIs and degrees of glucose tolerance.

ABBREVIATIONS

AACE = American Association of Clinical Endocrinologists BMI = body mass index GH = growth hormone GHD = GH deficiency GHRH = GH-releasing hormone GHS = GH secretagogue GST = glucagon stimulation test IGF = insulin-like growth factor IGFBP-3 = IGF-binding protein 3 ITT = insulin tolerance test ROC = receiver operating characteristic WB-GST = weight-based GST.

The effects of dietary protein and amino acids on skeletal metabolism

Dietary protein is required for optimal skeletal growth and maturation. Although Recommended Dietary Allowances (RDAs) exist for global dietary protein intake, the level and sources of dietary protein that are optimal for skeletal health over the life continuum have not been established. This is partly due to the difficulty in quantifying the effects of variable levels of a nutrient's intake over a lifetime as well as the complex nature of the relationships between dietary protein and calcium economy. Areas of current uncertainty include the precise source and amount of dietary protein required for optimal skeletal accretion and maintenance of skeletal mass, as well as the site-specific effects of dietary protein. The cellular and molecular mechanisms that underpin the actions of dietary protein on mineral metabolism and skeletal homeostasis remain unclear. This review attempts to summarize recent data bearing on these questions.

Impaired Pituitary Axes Following Traumatic Brain Injury

Pituitary dysfunction following traumatic brain injury (TBI) is significant and rarely considered by clinicians. This topic has received much more attention in the last decade. The incidence of post TBI anterior pituitary dysfunction is around 30% acutely, and declines to around 20% by one year. Growth hormone and gonadotrophic hormones are the most common deficiencies seen after traumatic brain injury, but also the most likely to spontaneously recover. The majority of deficiencies present within the first year, but extreme delayed presentation has been reported. Information on posterior pituitary dysfunction is less reliable ranging from 3%-40% incidence but prospective data suggests a rate around 5%. The mechanism, risk factors, natural history, and long-term effect of treatment are poorly defined in the literature and limited by a lack of standardization. Post TBI pituitary dysfunction is an entity to recognize with significant clinical relevance. Secondary hypoadrenalism, hypothyroidism and central diabetes insipidus should be treated acutely while deficiencies in growth and gonadotrophic hormones should be initially observed.

Implications of ghrelin and hexarelin in diabetes and diabetes-associated heart diseases

Ghrelin and its synthetic analog hexarelin are specific ligands of growth hormone secretagogue (GHS) receptor. GHS have strong growth hormone-releasing effect and other neuroendocrine activities such as stimulatory effects on prolactin and adrenocorticotropic hormone secretion. Recently, several studies have reported other beneficial functions of GHS that are independent of GH. Ghrelin and hexarelin, for examples, have been shown to exert GH-independent cardiovascular activity. Hexarelin has been reported to regulate peroxisome proliferator-activated receptor gamma (PPAR-γ) in macrophages and adipocytes. PPAR-γ is an important regulator of adipogenesis, lipid metabolism, and insulin sensitization. Ghrelin also shows protective effects on beta cells against lipotoxicity through activation of phosphatidylinositol-3 kinase/protein kinase B, c-Jun N-terminal kinase (JNK) inhibition, and nuclear exclusion of forkhead box protein O1. Acylated ghrelin (AG) and unacylated ghrelin (UAG) administration reduces glucose levels and increases insulin-producing beta cell number, and insulin secretion in pancreatectomized rats and in newborn rats treated with streptozotocin, suggesting a possible role of GHS in pancreatic regeneration. Therefore, the discovery of GHS has opened many new perspectives in endocrine, metabolic, and cardiovascular research areas, suggesting the possible therapeutic application in diabetes and diabetic complications especially diabetic cardiomyopathy. Here, we review the physiological roles of ghrelin and hexarelin in the protection and regeneration of beta cells and their roles in the regulation of insulin release, glucose, and fat metabolism and present their potential therapeutic effects in the treatment of diabetes and diabetic-associated heart diseases.

Growth hormone deficiency in treated acromegaly

Growth hormone deficiency (GHD) of the adult is characterized by reduced quality of life (QoL) and physical fitness, skeletal fragility, and increased weight and cardiovascular risk. Hypopituitarism may develop in patients after definitive treatment of acromegaly, but an exact prevalence of GHD in this population is still uncertain owing to limited awareness and the scarce and conflicting data available on this topic. Because acromegaly and GHD may yield adverse consequences on similar target systems, the final outcomes of some complications of acromegaly may be further affected by the occurrence of GHD. However, it is still largely unknown whether patients with post-acromegaly GHD may benefit from GH replacement. We review the diagnostic, clinical, and therapeutic aspects of GHD in adult patients treated for acromegaly.

Acute presentation of craniopharyngioma in children and adults in a Danish national cohort

We aimed to study the occurrence of acute-onset symptoms at initial presentation in a national Danish cohort of patients with childhood- or adult-onset craniopharyngioma, and to investigate potential risk factors for acute presentation. Medical records of 189 consecutive patients (39 children, 150 adults) presenting with craniopharyngioma during the period 1985-2004 were reviewed, and data regarding initial symptoms, neuroimaging results, vision and pituitary function were systematically collected. Acute symptoms preceding hospital admission were noted. Subgroup analyses were based on age, gender and calendar year period. Potential risk factors for acute presentation were analysed through uni- and multivariate analyses. Acute symptoms were reported in 24 (13%) patients. Acute visual symptoms, headache, nausea or vomiting were most frequently reported, and acute symptoms were more frequent among children (28%) than among adults (9%) (P < 0.01). There were no differences according to sex or calendar year period. Hydrocephalus was present in half of childhood cases and one-fifth of adult patients (P < 0.001). Intra-tumour haemorrhage was seen in two cases. Acute symptoms were more frequent among patients with tumours occupying the third ventricle (P < 0.01), radiologic signs of calcification (P < 0.05) or hydrocephalus (P < 0.01). In multivariate analysis, however, only childhood onset (P < 0.05) and calcification (P < 0.05) were independent risk factors for acute presentation. Craniopharyngioma presented with acute symptoms in 13% of patients. Childhood onset and radiologic signs of calcification were independent risk factors for acute presentation. Intra-tumour haemorrhage was rare.

Prolactin insufficiency but normal thyroid hormone levels after cranial radiotherapy in long-term survivors of childhood leukaemia

BACKGROUND

Acute lymphoblastic leukaemia (ALL) patients treated with cranial radiotherapy (CRT) have an increased risk of GH deficiency (GHD). Little is known about insufficiencies of prolactin (PRL) and TSH, but also lactation failure has been reported in this population.

OBJECTIVE

To study the long-term outcome of CRT on PRL and thyroid hormone levels in GHD ALL patients and the prevalence of lactation failure.

DESIGN

Case-control study.

PATIENTS

We examined 40 GHD and 4 GH insufficient ALL patients, in median 20 years (range: 8-27) after ALL diagnosis and 44 matched population controls.

MEASUREMENTS

PRL secretion (area under the curve; AUC) after GHRH-arginine test in all patients and matched controls, and PRL and TSH AUC after a TRH-test in 13 patients and 13 controls. And basal PRL and thyroid hormone levels after 5 years with GH therapy and 8 years without GH therapy.

RESULTS

Compared with controls, ALL patients had significantly lower basal and AUC PRL after GHRH-Arginine (P = 0·03, P = 0·02), and AUC PRL after TRH (P = 0·001). After 5 and 8 years, PRL levels decreased further (P = 0·01, P = 0·03), but thyroid hormones remained normal at baseline and at follow-up. PRL insufficiency was significantly associated with increased levels of BMI and insulin. Six out of seven pregnant ALL women reported lactation failure.

CONCLUSIONS

Long-term ALL survivors treated with CRT have GHD and PRL insufficiency, and a high prevalence of lactation failure, but thyroid hormones remained normal. PRL insufficiency was associated with cardiovascular risk.

Approach to testing growth hormone (GH) secretion in obese subjects

Identification of adults with GH deficiency (GHD) is challenging because clinical features of adult GHD are not distinctive and because clinical suspicion must be confirmed by biochemical tests. Adults are selected for testing for adult GHD if they have a high pretest probability of GHD, ie, if they have hypothalamic-pituitary disease, if they have received cranial irradiation or central nervous system tumor treatment, or if they survived traumatic brain injury or subarachnoid hemorrhage. Testing should only be carried out if a decision has already been made that if deficiency is found it will be treated. There are many pharmacological GH stimulation tests for the diagnosis of GHD; however, none fulfill the requirements for an ideal test having high discriminatory power; being reproducible, safe, convenient, and economical; and not being dependent on confounding factors such as age, gender, nutritional status, and in particular obesity. In obesity, GH secretion is reduced, GH clearance is enhanced, and stimulated GH secretion is reduced, causing a false-positive result. This functional hyposomatotropism in obesity is fully reversed by weight loss. In conclusion, GH stimulation tests should be avoided in obese subjects with very low pretest probability.

The arginine and GHRP-2 tests as alternatives to the insulin tolerance test for the diagnosis of adult GH deficiency in Japanese patients: a comparison

The arginine + GHRH test has been established as an alternative to the insulin tolerance test (ITT) for the diagnosis of adult GH deficiency (AGHD). However, the glucagon, arginine, and GH releasing peptide-2 (GHRP-2) test are recommended as alternatives in Japan. The objective of this study was to evaluate the arginine and GHRP-2 tests as alternatives to the ITT for the diagnosis of AGHD in a Japanese population. Three stimulation tests (ITT, arginine test, and GHRP-2 test) were conducted in 71 pre-operative adult patients with pituitary tumors (age, 18-65 years). The peak GH responses to each test were examined. The peak GH responses were significantly lower with the ARG test (median 4.43 μg/L) (p < 0.0001) than with the ITT (median 9.38 μg/L), and the peak GH responses with the GHRP-2 test (median 28.88 μg/L) were higher (p < 0.0001). However, among the AGHD patients, there was no significant difference between the peak GH responses to the ARG test and the ITT. The sensitivities and specificities of the ARG / GHRP-2 tests compared to the ITT for the diagnosis of severe AGHD (peak GH responses to ITT ≤ 1.8 μg/L) were 93.8% / 81.3% and 85.5% / 94.5%, respectively. The arginine and GHRP-2 stimulation tests are acceptable alternatives to the ITT for the diagnosis of AGHD in Japanese patients. The method and criterion for the diagnosis of AGHD should be reconsidered and adjusted to each population.

Metabolic effects of a growth hormone-releasing factor in obese subjects with reduced growth hormone secretion: a randomized controlled trial

CONTEXT

Obesity is associated with reduced GH secretion and increased cardiovascular disease risk.

OBJECTIVE

We performed this study to determine the effects of augmenting endogenous GH secretion on body composition and cardiovascular disease risk indices in obese subjects with reduced GH secretion.

DESIGN, PATIENTS AND METHODS

A randomized, double-blind, placebo-controlled study was performed involving 60 abdominally obese subjects with reduced GH secretion. Subjects received tesamorelin, a GHRH(1-44) analog, 2 mg once daily, or placebo for 12 months. Abdominal visceral adipose tissue (VAT) was assessed by abdominal computed tomography scan, and carotid intima-media thickness (cIMT) was assessed by ultrasound. Treatment effect was determined by longitudinal linear mixed-effects modeling.

RESULTS

VAT [-16 ± 9 vs.19 ± 9 cm(2), tesamorelin vs. placebo; treatment effect (95% confidence interval): -35 (-58, -12) cm(2); P = 0.003], cIMT (-0.03 ± 0.01 vs. 0.01 ± 0.01 mm; -0.04 (-0.07, -0.01) mm; P = 0.02), log C-reactive protein (-0.17 ± 0.04 vs. -0.03 ± 0.05 mg/liter; -0.15 (-0.30, -0.01) mg/liter, P = 0.04), and triglycerides (-26 ± 16 vs. 12 ± 8 mg/dl; -37 (-67, -7) mg/dl; P = 0.02) improved significantly in the tesamorelin group vs. placebo. No significant effects on abdominal sc adipose tissue (-6 ± 6 vs. 3 ± 11 cm(2); -10 (-32, +13) cm(2); P = 0.40) were seen. IGF-I increased (86 ± 21 vs. -6 ± 8 μg/liter; 92 (+52, +132) μg/liter; P < 0.0001). No changes in fasting, 2-h glucose, or glycated hemoglobin were seen. There were no serious adverse events or differences in adverse events between the groups.

CONCLUSION

Among obese subjects with relative reductions in GH, tesamorelin selectively reduces VAT without significant effects on sc adipose tissue and improves triglycerides, C-reactive protein, and cIMT, without aggravating glucose.

Growth hormone deficiency in the transition period: body composition and gonad function

Recombinant GH therapy is normally administered to GH-deficient children in order to achieve a satisfactory height - the main target during childhood and adolescence. However, the role of GH does not end once final height has been reached, but continues during the so-called transition period. In this phase of life, the body undergoes several changes, both physical and psychological, that culminate in adulthood. During this period, GH has a part in numerous metabolic functions. These include the lipid profile, where it increases HDL and reduces LDL, with the global effect of cardiovascular protection. It also has important effects on body composition (improved muscle strength and lean body mass and reduced body fat), the achievement of proper peak bone density, and gonad maturation. Retesting during the transition period, involving measurement of IGF-I plus a provocative test (insulin tolerance test or GHRH + arginine test), is thus necessary to establish any persistent GH deficiency requiring additional replacement therapy. The close cooperation of the medical professionals involved in the patient's transition from a pediatric to an adult endocrinologist is essential. The aim of this review is to point out the main aspects of GH treatment on body composition, metabolic and gonad functions in the transition period.

Vertebral fractures in males with prolactinoma

Data on osteoporotic fractures in hyperprolactinemia are limited. An increased prevalence of radiological vertebral fractures was recently observed in women with prolactin (PRL)-secreting adenoma, whereas it is unknown whether this observation may reflect a more general increased risk of fractures in this disease and whether the prevalence of fractures in males is affected by gonadal status. Thirty-two males (median age 47 years, range: 22-79) with PRL-secreting pituitary adenoma (10 with microadenoma and 22 with macroadenoma) and 64 control males, with normal PRL values and with comparable age to patients with hyperprolactinemia, were evaluated for vertebral fractures by a morphometric approach and for bone mineral density (BMD) by a dual-energy X-ray absorptiometry at lumbar spine. Vertebral fractures were shown in 12 patients with PRL-secreting adenoma (37.5%) and in 5 controls (7.8%, P < 0.001). Fractured patients had lower BMD T-score (P = 0.007) and longer duration of disease (P < 0.001) as compared to patients who did not fracture. Fractures occurred more frequently (P = 0.03) in patients with untreated hyperprolactinemia versus patients treated with cabergoline whose frequency of vertebral fractures was still higher than control subjects. The prevalence of vertebral fractures was not significantly different between eugonadal and hypogonadal patients (33.3% vs. 38.5%; P = 0.8). Moreover, no significant (P = 0.4) difference in serum testosterone values was found between fractured and not fractured males. Hyperprolactinemia is associated with high prevalence of radiological vertebral fractures in men with PRL-secreting adenoma. These findings would also suggest that PRL excess may produce negative skeletal effects independently of hypogonadism.

Bone loss after childhood acute lymphoblastic leukaemia: an observational study with and without GH therapy

OBJECTIVE

Bone mineral density (BMD) in survivors of acute lymphoblastic leukaemia (ALL) seems to vary with time, type of treatments and GH status. We aimed to evaluate BMD in ALL patients with GH deficiency (GHD), with and without GH therapy.

DESIGN

Case-control study.

METHODS

We examined 44 (21 women) GHD patients (median 25 years) treated with cranial radiotherapy (18-24 Gy) and chemotherapy and matched population controls for BMD with dual-energy X-ray absorptiometry. For 5 and 8 years, two subgroups with (0.5 mg/day) (n=16) and without GH therapy (n=13) and matched controls were followed respectively.

RESULTS

At baseline, no significant differences in BMD or Z-scores at femoral neck and L2-L4 were recorded (all P>0.3). After another 8 years with GHD, the Z-scores at femoral neck had significantly decreased compared with baseline (0.0 to -0.5; P<0.03) and became lower at the femoral neck (P=0.05), and at L2-L4 (P<0.03), compared with controls. After 5 years of GH therapy, only female ALL patients had a significantly lower femoral neck Z-scores (P=0.03). The female ALL patients reached an IGF1 level of -0.7 s.d. and male patients reached the level of +0.05 s.d.

CONCLUSIONS

On average, 25 years after diagnosis, GH-deficient ALL patients experienced a significant decrease in Z-scores at femoral neck, and if Z-scores continue to decrease, there could be a premature risk for osteoporosis. GH therapy was not shown to have a clear beneficial effect on BMD. Whether higher GH doses, particularly in women, will improve Z-scores needs further investigation.

Cardiovascular risk, cardiac function, physical activity, and quality of life with and without long-term growth hormone therapy in adult survivors of childhood acute lymphoblastic leukemia

CONTEXT

Long-term data are missing in GH-treated acute lymphoblastic leukemia (ALL) patients. GH therapy may result in poorer outcome regarding cardiovascular (CV) and particularly cardiac effects than in patients with hypothalamic-pituitary disease.

OBJECTIVE

Our objective was to evaluate GH therapy on CV risk, cardiac function, physical activity, and quality of life in ALL patients treated with cranial radiotherapy (18-24 Gy) and chemotherapy (anthracycline dose 120 mg/m2).

DESIGN AND SETTING

We conducted a 5- and 8-yr open nonrandomized prospective study in a university hospital clinic.

STUDY PARTICIPANTS

Two groups of GH-deficient ALL patients (aged 25 yr; range 19-32 yr) and matched population controls participated.

INTERVENTIONS

One ALL group (n=16) received GH for 5 yr, and the other ALL group (n=13) did not receive GH therapy.

MAIN OUTCOME MEASURES

We evaluated the prevalence of CV risk factors and metabolic syndrome (International Diabetes Federation consensus), cardiac function (echocardiography), and quality of life and physical activity questionnaires.

RESULTS

In comparison with 8 yr without, 5 yr with GH therapy resulted in significant positive changes in plasma glucose (-0.5 vs. 0.6 mmol/liter, P=0.002), apolipoprotein B/apolipoprotein A1 ratio (-0.1 vs. 0.0, P=0.03), and high-density lipoprotein-cholesterol (0.20 vs.-0.01 mmol/liter, P=0.008) and a significant reduction in the prevalence of metabolic syndrome (P=0.008). No significant difference in the left-ventricular systolic function or in physical activity and quality of life was recorded before and after 5 or 8 yr, respectively (all P>0.3).

CONCLUSION

GH therapy reduced the CV risk in this young ALL population but resulted in no clear benefit or deterioration in cardiac function.

The rational use of pituitary stimulation tests

BACKGROUND

Diseases of the pituitary gland can lead to the dysfunction of individual hormonal axes and to the corresponding clinical manifestations. The diagnostic assessment of pituitary function has not yet been standardized.

METHODS

The members of the Neuroendocrinology Section and the Pituitary Study Group of the German Society for Endocrinology (Deutsche Gesellschaft für Endokrinologie) prepared outlines of diagnostic methods for the evaluation of each of the pituitary hormonal axes. These outlines were discussed in open session in recent annual meetings of the Section and the Study Group.

RESULTS

For the evaluation of the thyrotropic axis, basal TSH and free T4 usually suffice. For the evaluation of the gonadotropic axis in men, the testosterone level should be measured; if the overall testosterone level is near normal, then calculating the free testosterone level may be additionally useful. In women, an intact menstrual cycle is sufficient proof of normal function. In the absence of regular menstruation, measurement of the basal estradiol and gonadotropin levels aids in the diagnosis of the disturbance. For the evaluation of the adrenocorticotropic axis, the basal cortisol level may be helpful; provocative testing is in many cases necessary for precise characterization. The evaluation of the somato-tropic axis requires provocative testing. Aside from the insulin tolerance test, the GHRH-arginine test has become well established. Reference ranges normed to the body mass index (BMI) are available.

CONCLUSION

The diagnostic evaluation of pituitary insufficiency should proceed in stepwise fashion, depending on the patient's clinical manifestations and underlying disease. For some pituitary axes, measurement of basal hormone levels suffices; for others, stimulation tests are required. In general, the performance of combined pituitary tests should be viewed with caution.

Tall stature without growth hormone: four male patients with aromatase deficiency

CONTEXT

From preliminary observations, GH-IGF-I seems to be compromised in men with aromatase deficiency. The GH deficiency (GHD) coexists paradoxically with tall stature, raising the question whether or not a true GHD is part of this rare syndrome.

OBJECTIVE

To evaluate the GH secretion in aromatase-deficient men, their GH response to the GHRH plus arginine (GHRH-ARG) test was compared with that of normal subjects. The effect of estrogen replacement treatment on the GH-IGF-I axis in aromatase-deficient men was evaluated before and during therapy.

DESIGN AND SETTING

A case-control study was conducted.

PATIENTS

Four adult men with aromatase deficiency were compared with 12 normal subjects.

MAIN OUTCOME MEASURES

We measured the GH response to GHRH-ARG in aromatase-deficient men (at baseline and during estrogen treatment) and in normal subjects. Basal serum IGF-I was measured in both patients and controls.

RESULTS

The response of GH to GHRH-ARG was severely impaired in men with aromatase deficiency and resulted in significantly lower (P < 0.001) levels than in normal subjects. Although normal, serum IGF-I levels were also significantly lower (P < 0.001) than in normal subjects. Both GH peak and IGF-I concentrations were not modified by estrogen therapy in men with aromatase deficiency.

CONCLUSIONS

In aromatase-deficient men, GH response to potent provocative stimuli is impaired and is not restored by exogenous estrogens. Furthermore, a tall stature may be reached, notwithstanding the coexistence of GHD, if a prolonged time for growth is available due to a delay in bone maturation, and other growth factors different from GH (mainly insulin) promote growth.

Growth hormone/insulin-like growth factor-I axis in obstructive sleep apnea syndrome: an update

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant mortality and morbidity when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. In particular, obese patients with OSAS show a peculiar reduction of both spontaneous and stimulated GH secretion coupled with reduced IGF-I concentrations and impaired peripheral sensitivity to GH. These endocrine abnormalities are more marked than those observed in non-apneic obese subjects, and are likely to be due to the effects of hypoxia and sleep fragmentation on hormone secretory pattern. The GH/IGF-I axis activity disruption can be responsible, at least in part, for metabolic alterations, which are common in OSAS and increase the risk of cardiovascular events as well as mortality. Effective assessment and management of OSAS may correct endocrine changes, improve quality of life, and prevent associated morbidity or death.

[Neuroendocrine dysfunction and brain damage. A consensus statement]

This consensus statement aims to enhance awareness of the incidence and risks of hypopituitarism in patients with traumatic brain injury (TBI) and/or brain hemorrhages among physicians treating patients with brain damage. The importance of this problem is related not only to the frequency of TBI but also to its prevalence in younger populations. The consequences of TBI are characterized by a series of symptoms that depend on the type of sequels related to neuroendocrine dysfunction. The signs and symptoms of hypopituitarism are often confused with those of other sequels of TBI. Consequently, patients with posttraumatic hypopituitarism may receive suboptimal rehabilitation unless the underlying hormone deficiency is identified and treated. This consensus is based on the recommendation supported by expert opinion that patients with a TBI and/or brain hemorrhage should undergo endocrine evaluation in order to assess pituitary function and, if deficiency is detected, should receive hormone replacement therapy.

Neuroendocrine alterations in obese patients with sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant morbidity and mortality when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. Obese patients with OSAS show a reduction of both spontaneous and stimulated growth hormone (GH) secretion coupled to reduced insulin-like growth factor-I (IGF-I) concentrations and impaired peripheral sensitivity to GH. Hypoxemia and chronic sleep fragmentation could affect the sleep-entrained prolactin (PRL) rhythm. A disrupted Hypothalamus-Pituitary-Adrenal (HPA) axis activity has been described in OSAS. Some derangement in Thyroid-Stimulating Hormone (TSH) secretion has been demonstrated by some authors, whereas a normal thyroid activity has been described by others. Changes of gonadal axis are common in patients with OSAS, who frequently show a hypogonadotropic hypogonadism. Altogether, hormonal abnormalities may be considered as adaptive changes which indicate how a local upper airway dysfunction induces systemic consequences. The understanding of the complex interactions between hormones and OSAS may allow a multi-disciplinary approach to obese patients with this disturbance and lead to an effective management that improves quality of life and prevents associated morbidity or death.

Neuroendocrine function following traumatic brain injury and subsequent intensive care treatment: a prospective longitudinal evaluation

Neuroendocrine dysfunction following traumatic brain injury (TBI) has been described extensively. However, few studies are longitudinal and most lack subtle radiological, clinical, and repetitive endocrine assessment in the acute phase. Accordingly, we prospectively assessed neuroendocrine function in 71 patients after TBI. Injury was documented by a computed tomography (CT). During the first week, critical clinical data (Glasgow Coma Score, APACHE score), treatment variables such as duration of analgosedation for mechanical ventilation, were related to basal pituitary function. More than 2 years later, a subgroup of patients was re-evaluated using dynamic testing with ACTH and GHRH-arginine tests. The Pearson's correlation analysis and Mann-Whitney rank sum test for group differences were used for statistical analysis. None of the CT findings predicted neuroendocrine dysfunction following TBI. The adaptive response to critical illness with significantly elevated cortisol levels on admission and decreased levels thereafter in patients ventilated for more than 24 h (p < 0.05) was attenuated following severe TBI (p < 0.05). However, the coincidence of low serum cortisol and increased urinary excretion of glucocorticoid metabolites in about 80% of patients challenges the relevance of basal hormone measurements. In ventilated patients, total T3 and free T4 were decreased (p < 0.05), TSH was low on day 3 (p < 0.05), and a gonadotropic insufficiency was present (p < 0.05). The thyrotropic and gonadotropic system recovered completely within the follow-up period. With regard to the somatotropic system, neither brain injury severity nor mechanical ventilation was associated with an insufficiency during the acute phase post-injury. However, initially low GH levels predicted a persistent deficiency (r = 0.731, p < 0.001). We conclude that both severe TBI and prolonged mechanical ventilation result in hormonal disturbances early after injury, suggesting a pathophysiological response to brain injury and subsequent intensive care treatment rather than morphological damage.

Determinants of GH-releasing hormone and GH-releasing peptide synergy in men

Age, sex steroids, and abdominal-visceral fat (AVF) jointly affect pulsatile growth hormone (GH) secretion. Pulsatile GH secretion in turn is controlled by GH-releasing hormone (GHRH), GH-releasing peptide (GHRP), and somatostatin. Marked stimulation of pulsatile GH secretion is achieved via GHRH-GHRP synergy. Nonetheless, how key modulators of GH secretion, such as age, sex steroids, and body mass index, modify GHRH-GHRP synergy is not known. The present strategy was to 1) infuse GHRH and GHRP-2 simultaneously to evoke synergy and 2) downregulate the gonadal axis with leuprolide and then restore placebo (Pl) or testosterone (T) to clamp the sex steroid milieu. Forty-seven men [18-74 yr of age, T = 7-1,950 ng/dl, estradiol (E(2)) = 5-79 pg/ml, insulin-like growth factor (IGF)-I = 115-817 microg/l, AVF = 11-349 cm(2)] were studied. GHRH-GHRP synergy correlated negatively with age and AVF (both P < 0.001) and positively with IGF-I (P < 0.001) and IGF-binding protein (IGFBP)-3 (P = 0.031). Unstimulated basal (nonpulsatile) GH secretion correlated positively with T (P = 0.015) and E(2) (P = 0.004) concentrations. Fasting pulsatile GH secretion varied negatively with age (P = 0.017) and positively with IGF-I (P = 0.002) and IGFBP-3 (P = 0.001). By stepwise forward-selection multivariate analyses, AVF, IGF-I, and IGFBP-3 together explained 60% of the variability in GHRH-GHRP synergy (P < 0.001), E(2) accounted for 17% of the variability in basal GH secretion (P = 0.007), and IGF-I explained 20% of the variability in fasting pulsatile GH secretion (P = 0.002). In conclusion, a paradigm examining GHRH-GHRP synergy under a sex steroid clamp reveals highly selective control of basal, pulsatile, and synergistic peptide-driven GH secretion by AVF, E(2), and IGF-I in healthy men.

Bone mineral density in young adult survivors of acute lymphoblastic leukemia

BACKGROUND

The purpose of the current study was to determine the prevalence of low bone mineral density (BMD) (ie, osteopenia) and identify factors associated with low BMD in young adult survivors of childhood acute lymphoblastic leukemia (ALL).

METHODS

Dual energy x-ray absorptiometry was used to evaluate BMD in 74 randomly selected, long-term childhood ALL survivors initially treated in Minneapolis/St. Paul, Minnesota. Growth hormone (GH)-releasing hormone-arginine stimulation testing was conducted to evaluate peak GH level, and insulin-like growth factor I (IGF-I) and other markers of endocrine functioning were also evaluated in relation to BMD.

RESULTS

The mean age at the time of interview was 30 years, and the mean time since diagnosis was 24 years. Low BMD (Z-score, < or = -1) was present in 24% of subjects, including 1 with osteoporosis. Low BMD was substantially more prevalent in men than in women and was strongly associated with short height. The mean height Z-score for those with low BMD was -1.44, compared with a height Z-score of -0.39 (P < .01) for those with normal BMD. GH insufficiency, low IGF-I Z-score, and current smoking were also suggestive risk factors for low BMD.

CONCLUSIONS

In this long-term follow-up study of childhood ALL survivors, low BMD was found to be more prevalent than expected based on population normative data, specifically in men. The health consequences of early-onset BMD problems in childhood ALL survivors need to be carefully monitored.

Long-term effects of growth hormone replacement therapy on thyroid function in adults with growth hormone deficiency

BACKGROUND

Clinical studies on the effect of growth hormone (GH) on thyroid function in patients with GH deficiency are contradictory. Further, the majority of published observations are limited to the first 6-12 months of GH replacement therapy. The aim of our study was to estimate the incidence of clinically relevant hypothyroidism in a cohort of patients with adult GH deficiency (AGHD) during long-term therapy with recombinant human GH (rhGH).

METHODS

The study was designed as a retrospective collection of data on thyroid function in 49 AGHD patients of whom 44 (90%) had multiple hormone deficiency. Thirty-seven patients (76%) were on stable levothyroxine (LT4) replacement therapy (HYPO), and 12 (24%) were euthyroid (EUT). Therapy with rhGH was started at a dose of 3.5 microg/kg body weight and adjusted according to insulin-like growth factor-I (IGF-I) levels. At baseline, 6 months, 12 months, and yearly thereafter we measured free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone, and IGF-I. Study outcome was fT4 level below the normal range (9 pmol/L), irrespectively of fT3 or thyroid-stimulating hormone levels.

RESULTS

During a follow-up of 115 patient-years, mean fT4 level decreased significantly, although remaining within the normal range (p = 0.0242; month 48 vs. baseline). The largest decrease was between baseline and month 6, when fT4 decreased of 1.43 pmol/L (95% confidence interval, 0.33-2.53) per 1 unit (microg/kg body weight) increase in rhGH dose. The incidence of hypothyroidism was 1.2 (HYPO group) and 6.7 (EUT group) events per 100 patient-years.

CONCLUSION

We confirm that in patients with AGHD, rhGH therapy is associated with a small, although significant, decrement of fT4 in the first 6 months of replacement therapy. However, the incidence of hypothyroidism is low. Monitoring of thyroid function during rhGH therapy is advisable, particularly in the first year of therapy when the largest decrease in fT4 occurs.

Chronic hypopituitarism after traumatic brain injury: risk assessment and relationship to outcome

OBJECTIVE

Chronic pituitary dysfunction is increasingly recognized as a sequela of traumatic brain injury. We sought to define the incidence, risk factors, and neurobehavioral consequences of chronic hormonal deficiencies after complicated mild, moderate, or severe traumatic brain injury.

METHODS

Patients aged 14 to 80 years were prospectively enrolled at the time of injury and assessed at 3 and 6 to 9 months after injury for hormonal function and neurobehavioral consequences. Major and minor (subclinical) hormonal deficiencies, including growth hormone deficiency (GHD) and growth hormone insufficiency (GHI), were identified. Acute injury characteristics, neurobehavioral, and quality of life measures were compared in patients with and without major hormonal deficits by the use of multivariate analysis.

RESULTS

Out of 70 patients (mean age, 32 yr; median Glasgow Coma Scale score, 7; 19% women) tested at 6 to 9 months after injury, 15 (21%) had at least one major hormonal deficiency, 20 (29%) had minor deficiencies, and 30 (43%) had major and/or minor deficiencies. Patients with major deficiencies included 16% with GHD or GHI, 10.5% with hypogonadism, and 1.4% with diabetes insipidus. None of the patients required adrenal or thyroid replacement. At 6 to 9 months after injury, patients with major hormonal deficits had more abnormal acute computed tomographic findings (P = 0.014), greater acute and chronic body mass index (P < 0.01), and a worse Disability Rating Scale score (multivariate P = 0.04). Compared with the 59 growth hormone-sufficient patients, the 11 patients with GHD or GHI had worse Disability Rating Scale scores (multivariate P = 0.04), greater rates of depression, (90 versus 53%; multivariate P = 0.06), and worse quality of life in the Short Form-36 domains of energy and fatigue (multivariate P = 0.03), emotional well-being (multivariate P = 0.02), and general health (multivariate P = 0.07).

CONCLUSION

Chronic hypopituitarism warranting hormone replacement occurs in approximately 20% of patients after complicated mild, moderate, or severe traumatic brain injury and is associated with more severe brain injuries and increased disability. GHD and GHI are also associated with increased disability, poor quality of life, and a greater likelihood of depression. The clinical significance of minor hormonal deficits, which occur in almost 30% of patients, warrants further study. Given that major deficiencies are readily treatable, routine pituitary hormonal testing within 6 months of injury is indicated for this patient population.

Effect of long-term cabergoline therapy on the immunological pattern and pituitary function of patients with idiopathic hyperprolactinaemia positive for antipituitary antibodies

OBJECTIVE

The occurrence of antipituitary antibodies (APA) in patients with idiopathic hyperprolactinaemia (IH) and the effects of dopamine agonists on these antibodies and long-term pituitary function outcome have been so far not evaluated. This longitudinal study was aimed at investigating, in patients with IH the occurrence of APA and the effect of cabergoline on the pituitary function and behaviour of APA.

DESIGN

Sixty-six patients with IH were studied. APA (by indirect immunofluorescence) and pituitary function were investigated every year for 3 years.

RESULTS

Seventeen patients resulted APA positive (Group 1) and 49 APA negative (Group 2). Eight patients of Group 1 (Group 1a) and 24 of Group 2 (Group 2a) were asymptomatic and then not treated; instead, nine patients in Group 1 (Group 1b) and 25 in Group 2 (Group 2b), showing symptoms of hyperprolactinaemia, were treated with cabergoline for 2 years. Among the untreated patients, during the follow-up, those with APA positive (Group 1a) showed an increase of APA titres and PRL levels with partial pituitary impairment in some of them; instead those with APA negative (Group 2a) persisted negative with normal pituitary function despite persistent hyperprolactinaemia. Among the treated patients, those with APA positive (Group 1b) showed normalization of PRL levels, APA disappearance and recovery of pituitary function (when initially impaired) during cabergoline treatment, persisting also at last observation (off-therapy). Instead all patients of Group 2b persisted with APA negative during the follow-up with normalization of PRL levels and stable normal pituitary function during cabergoline therapy but showing a further increase of PRL at the last observation.

CONCLUSIONS

The presence of APA in some patients with IH suggests a possible occurrence of autoimmune hypophysitis at potential/subclinical stage; an early and prolonged cabergoline therapy could interrupt the progression to an overt clinical stage of the disease. However, the small amount of patients investigated suggests caution against generalization of our assumption and prompts to further controlled studies on a more numerous population to verify these conclusions.

Diagnosis of adult GH deficiency

The current guidelines for the diagnosis of adult GHD are mainly based on the statements from the GH Research Society Consensus from Port Stevens in 1997. It is stated that diagnosis of adult GHD must be shown biochemically by provocative tests within the appropriate clinical context. The insulin tolerance test (ITT) was indicated as that of choice and severe GHD defined by a GH peak lower than 3 microg/L. The need to rely on provocative tests is based on evidence that that the measurement of IGF-I as well as of IGFBP-3 levels does not distinguish between normal and GHD subjects. Hypoglycemia may be contraindicated; thus, alternative provocative tests were considered, provided they are used with appropriate cut-off limits. Among classical provocative tests, arginine and glucagon alone were indicated as alternative tests, although less discriminatory than ITT. Testing with the combined administration of GHRH plus arginine was recommended as an alternative to ITT, mostly taking into account its marked specificity. Based on data in the literature in the last decade, the GRS Consensus Statements should be appropriately amended. Regarding the appropriate clinical context for the suspicion of adult GHD, one should evaluate patients with hypothalamic or pituitary disease or a history of cranial irradiation, as well as those with childhood-onset GHD are at obvious risk as adults for severe GHD. Brain injuries (trauma, subarachnoid hemorrage, tumours of the central nervous system) very often cause acquired hypopituitarism, including severe GHD. Given the epidemiology of brain injuries, the important role of the endocrinologist in providing major clinical benefit to brain injured patients who are still undiagnosed should be underscored. From the biochemical point of view, although normal IGF-I levels do not rule out severe GHD, very low IGF-I levels in patients highly suspected for GHD (i.e. patients with childhood-onset, severe GHD or with multiple hypopituitarism acquired in adulthood) can be considered as definitive evidence for severe GHD; thus, these patients would skip provocative tests. Patients suspected for adult GHD with normal IGF-I levels must be investigated by provocative tests. ITT remains a test of reference but it should be recognized that other tests are as reliable as ITT. Glucagon as classical test and, particularly, new maximal tests such as GHRH in combination with arginine or GH secretagogues (GHS) (i.e. GHRP-6) have well defined cut-off limits, are reproducible, able to distinguish between normal and GHD subjects. Overweight and obesity have confounding effect on the interpretation of the GH response to provocative tests. In adults cut-off levels of GH response below which severe GHD is demonstrated must be appropriate to lean, overweight and obese subjects to avoid false positive diagnosis in obese adults and false negative diagnosis in lean GHD patients. Finally, normative values of GH response to provocative tests may depend on age, particularly in the transitional age; the normative cut-off levels of GH response to ITT in this phase of life are now available.

Unreliability of classic provocative tests for the diagnosis of growth hormone deficiency

In this study we investigated 9 prepubertal children with blunted GH response to classic pharmacological stimuli in contrast with normal auxological evaluation. The children were followed to evaluate their growth velocity for a longer period before starting replacement GH therapy. To evaluate the pituitary reserve a supraphysiologic stimulus such as GHRH plus arginine was used. Serum GH levels were measured by a time-resolved immunofluorimetric assay before and after 1 microg/kg body weight iv injection of GHRH, while serum PRL, IGF-I, and insulin were evaluated only in basal conditions using an automatic immunometric assay. Out of 9 studied subjects, 7 underwent GHRH plus arginine administration and showed a normal GH response; the parents of the remaining 2 children refused the test. Normal serum levels of PRL, IGF-I, insulin, and a normal insulin sensitivity were observed in all children. After 1 yr, the growth rate in each patient was further improved and reached almost normal values. Our results further confirm that the decision to start replacement GH therapy should be based on both auxological parameters and laboratory findings. The GHRH plus arginine test appears to be useful to identify false GH deficiency in children showing a blunted GH response to classic stimuli in contrast with normal growth rate.

Diagnosis of adult GH deficiency

Based on previous consensus statements, it has been widely accepted that the diagnosis of adult growth hormone deficiency (GHD) must be shown biochemically by provocative tests of GH secretion; in fact, the measurement of IGF-I as well as of other markers was considered unable to distinguish between normal and GHD subjects. The Insulin Tolerance Test (ITT) was indicated as that of choice and severe GHD defined by a GH peak lower than 3 microg/l. It is now recognized that, although normal IGF-I levels do not rule out severe GHD, very low IGF-I levels in patients highly suspected for GHD (i.e. patients with childhood-onset severe GHD or with multiple hypopituitarism acquired in adulthood) can be considered as definite evidence for severe GHD. However, patients suspected for adult GHD with normal IGF-I levels must be investigated by provocative tests. ITT remains a test of reference but it should be recognized that other tests are as reliable as ITT. Glucagon as classical test and, particularly, new maximal tests such as GHRH in combination with arginine or GH secretagogues (GHS) (i.e. GHRP-6) have well defined cut-off limits, are reproducible, able to distinguish between normal and GHD subjects. Overweight and obesity have confounding effect on the interpretation of the GH response to provocative tests. In adults cut-off levels of GH response below which severe GHD is demonstrated must be appropriate to lean, overweight and obese subjects to avoid false positive diagnosis in obese adults and false negative diagnosis in lean GHD patients.

An audit of treatment outcome in acromegalic patients attending our center at Bergamo, Italy

BACKGROUND

Acromegaly is a chronic disease impacting on morbidity and mortality. Increased mortality is reverted after the achievement of hormonal targets. The relative role of treatment options is still matter of debate.

METHODS

A retrospective chart review was performed on all the acromegalic patients attending our center along the last 20 years.

RESULTS

Data about 159 patients (83 F) were retrieved and analyzed: 18% had been lost to follow-up, while follow-up was >5 years in 79%. Growth hormone (GH) at diagnosis was 24 microg/L (median, range 3-239). Pituitary MRI showed a macro-, micro-adenoma or no lesion in 73.6, 22.9, and 3.5%, respectively. Hyperprolactinemia (hyperPRL) was present in 20.8%. Ninety-six and 29 patients had been treated by neurosurgery (NS) and irradiated (RT), respectively. Drugs had been employed in 149 patients (in 58 as the only treatment). At the last evaluation, 22% of patients were cured (hypopituitarism and GH deficiency in 6.3%), 37.1% were controlled by ongoing pharmacological treatment, 22.6% had discordant GH and Insulin-like growth factor I (IGF-I) values, and 18.2% had still active disease (median follow-up in this last group was 9 months). By evaluating the outcome with a multimodal approach, safe GH and normal IGF-I had been achieved in 78 and 63.5% of the whole series, 80.5 and 59.7% in patients submitted to NS (and adjuvantly treated with drugs), 95.8 and 91.7% in those submitted to NS + RT (and drugs as well), 70.2 and 55.2% in those treated only with drugs (increased to 82.2 and 60.9% if considering only patients treated with modern long-acting drugs). Hypopituitarism had occurred in 25, 66.6, and 13.8% in the three groups, respectively. At multivariate analysis, previous RT and NS were significant positive predictors of cure, whereas previous NS, follow-up, and year of diagnosis were significant positive predictors of control. Diabetes was a negative predictor both of cure and control. Sex, age, baseline GH levels, hyperPRL, tumor size, extrasellar extension, and invasiveness were not independent predictors of either cure or control.

CONCLUSION

This series seems to indicate that a multimodal approach can achieve control of disease in most patients.

Body composition, muscle strength deficits and mobility limitations in adult survivors of childhood acute lymphoblastic leukemia

BACKGROUND

Chronicity of muscle weakness from cancer and its treatment may be problematic, particularly in those treated for cancer during childhood. We compared body composition, muscle strength, and mobility between 75 adult survivors of childhood acute lymphoblastic leukemia (ALL) and expected values based on population normative data.

METHODS

Subjects were young adults treated for childhood ALL between 1970 and 1986, selected randomly from participants in an ongoing study of cancer survivors. DeXA scans were performed to evaluate body composition, and myometry used to measure strength. Mobility was evaluated with the Timed Up and Go (TUG) and 2-min walk (TMW). One sample t-tests compared ALL survivors to population norms.

RESULTS

Males had 4.5% and females had 2.3% more body fat than expected (expected males 21.5%, females 36.0%). Males were 76.7 Newtons and females were 58.6 Newtons weaker in quadriceps strength than expected (expected males 569.87 N, females 464.67 N). Males walked 100.88 m and females walked 85.38 m less on the TMW (expected values: males 304.23 m, females 276.26 m), and took longer to complete the TUG (males 5.82 vs. 2.84 sec, females 5.88 vs. 3.00 sec) than expected. Treatment with cranial radiation and current growth hormone (GH) deficiency were associated with lower body weakness among females.

CONCLUSIONS

Young adult survivors of childhood ALL have strength and mobility deficits. Decreased strength may reduce ability to participate in physical activity, perpetuating fitness deficits in survivors of childhood ALL.

Deterioration of growth hormone (GH) response and anterior pituitary function in young adults with childhood-onset GH deficiency and ectopic posterior pituitary: a two-year prospective follow-up study

CONTEXT

The current criteria for definition of partial GHD in young adults are still a subject of debate.

OBJECTIVES

The objective of the study was to reinvestigate anterior pituitary function in young adults with congenital childhood-onset GHD associated with structural hypothalamic-pituitary abnormalities and normal GH response at the time of first reassessment of GH secretion.

DESIGN AND SETTING

This was a prospective explorative study conducted in a university research hospital.

PATIENTS AND METHODS

Thirteen subjects with a mean age of 17.2 +/- 0.7 yr and a peak GH after insulin tolerance test (ITT) higher than 5 microg/liter were recruited from a cohort of 42 patients with childhood-onset GHD and ectopic posterior pituitary at magnetic resonance imaging. GH secretion after ITT and GHRH plus arginine, IGF-I concentration, and body mass index, waist circumference, blood pressure, total cholesterol, and fibrinogen were evaluated at baseline and at 2-yr follow-up.

RESULTS

At mean age of 19.2 +/- 0.7 yr, the mean peak GH response decreased significantly after ITT (P = 0.00001) and GHRH plus arginine (P = 0.0001). GH peak values after ITT and GHRH plus arginine were less than 5 and 9 microg/liter in 10 and eight patients, respectively. Additional pituitary defects were documented in eight patients. Significant changes were found in the values of IGF-I sd score (P = 0.0026), waist circumference (P = 0.00001), serum total cholesterol (P = 0.00001), and serum fibrinogen (P = 0.0004).

CONCLUSIONS

The results of this study underline the importance of further reassessment of pituitary function in young adults with GHD of childhood-onset and poststimulation GH responses suggestive of partial GHD.

Recent Developments in Ghrelin Receptor Ligands

The 28-amino acid peptide ghrelin is a neuroendocrine hormone synthesized primarily in the stomach. It stimulates growth hormone secretion and appetite, thus promoting food intake and body-weight gain. The pharmacological properties of this peptide are mediated by the growth hormone secretagogue receptor type 1a (GHS-R1a). Given its wide spectrum of biological activities, it is evident that the discovery of ghrelin and its receptor has opened up many perspectives in the fields of neuroendocrine and metabolic research and has had an influence on such fields of internal medicine as gastroenterology, oncology, and cardiology. It is therefore increasingly likely that synthetic, peptidyl, and nonpeptidyl GHS-R1a ligands, acting as agonists, partial agonists, antagonists, or inverse agonists, could have both clinical and therapeutic potential. This review summarizes the various types of GHS-R1a ligands that have been described in the literature and discusses the recent progress made in this research area.

Attenuated pulse size, disorderly growth hormone and prolactin secretion with preserved nyctohemeral rhythm distinguish irradiated from surgically treated acromegaly patients

BACKGROUND

Radiation induces time-dependent loss of anterior pituitary function, attributed to damage of the pituitary gland and hypothalamic centres. The development of growth hormone deficiency (GHD) in irradiated acromegaly patients is not well defined.

OBJECTIVE

Detailed analysis of spontaneous 24-h GH and prolactin (PRL) secretion in relation to other pituitary functions and serum IGF-I concentrations in an attempt to find criteria for GHD in acromegalic patients with a GH response < 3 microg/l during the insulin tolerance test (ITT).

DESIGN

Plasma hormone profiles obtained by 10 min sampling for 24 h in postoperatively irradiated acromegalic patients, compared with patients cured by surgery only and matched healthy controls.

SETTING/PARTICIPANTS

University setting. Fifteen subjects in each group.

OUTCOME MEASURES

GH and PRL secretory parameters quantified by deconvolution, cluster, cosinor and approximate entropy (ApEn) analyses, IGF-I concentrations.

RESULTS

Irradiation attenuated pulsatile secretion of GH and PRL, but total PRL secretion was unchanged. GH and PRL secretory regularity were diminished. Circadian timing remained intact. Pulsatile GH secretion and IGF-I were correlated (R = 0.30, P = 0.04). Criteria of pulsatile GH secretion = 12 microg/l/24 h and ApEn = 0.800 separated 12 of 15 irradiated patients from all others.

CONCLUSION

Irradiated acromegaly patients with a subnormal GH response to ITT have very limited spontaneous GH secretion, with specific attenuation of the size of GH bursts and a highly irregular pattern, but with retained diurnal properties. These patients are thus likely GH-deficient and might benefit from GH replacement.

Growth hormone reserve in adult beta thalassemia patients

Reduced serum insulin-like growth factor-1 (IGF-1) and hypogonadotrophic hypogonadism are common features of adult beta-thalassemia, and warrant evaluation of the growth hormone (GH)-IGF-1 axis. The aim of this study was to determine GH reserve in beta-thalassemia patients (9 females, 7 males, 15 major, 1 intermedia), age 29.3 +/- 6.9 years, BMI 21.3 +/- 1.9 kg/m2, and in 20 age, sex and BMI-matched healthy controls, using the GH-releasing hormone (GHRH)-arginine test. The associations between peak GH response and hormonal and biochemical indices were evaluated. Using BMI-related cut-off limits for peak GH response in the GHRH-arginine test, 4/16 beta-thalassemia patients had peak GH lower than 11.5 microg/l, the cut-off limit suggested for lean subjects, and were diagnosed as GH deficient (GHD). Using 9 microg/l as the cut-off limit 2/16 patients were GHD. Reduced serum IGF-1 and IGFBP-3 were present in 69% and 19% of the patients, respectively. Peak GH did not correlate with serum IGF-1, TSH, and fT4 levels or gonadal status. Neither peak GH nor IGF-1 correlated with serum ferritin. Our findings suggest that GHD is present in up to a quarter of adult beta-thalassemia patients. The clinical benefits of GH therapy need to be determined. GHD alone does not account for the high prevalence of reduced IGF-1 in adult beta-thalassemia.

Growth hormone levels in the diagnosis of growth hormone deficiency in adulthood

Current guidelines for the diagnosis of adult growth hormone deficiency (GHD) state that the diagnosis must be proven biochemically by provocative testing that is done within the appropriate clinical context. The need for reliance on provocative testing is based on evidence that the evaluation of spontaneous growth hormone (GH) secretion over 24 h and the measurement of IGF-I and IGFBP-3 levels do not distinguish between normal and GHD subjects. Regarding IGF-I, it has been demonstrated that very low levels in patients highly suspected for GHD (i.e., patients with childhood-onset, severe GHD, or with multiple hypopituitarism acquired in adulthood) may be considered definitive evidence for severe GHD obviating the need for provocative tests. However, normal IGF-I levels do not rule out severe GHD and therefore adults suspected for GHD and with normal IGF-I levels must undergo a provocative test of GH secretion. The insulin tolerance test (ITT) is the test of choice, with severe GHD being defined by a GH peak less than 3 microg/l, the cut-off that distinguishes normal from GHD adults. The ITT is contraindicated in the presence of ischemic heart disease, seizure disorders, and in the elderly. Other tests are as reliable as the ITT, provided they are used with appropriate cut-off limits. Glucagon stimulation, a classical test, and especially new maximal tests such as GHRH in combination with arginine or GHS (i.e., GHRP-6) have well-defined cut-off limits, are reproducible, are independent of age and gender, and are able to distinguish between normal and GHD subjects. The confounding effect of overweight or obesity on the interpretation of the GH response to provocative tests needs to be considered as the somatotropic response to all stimuli is negatively correlated with body mass index. Appropriate cut-offs for lean, overweight, and obese subjects must be used in order to avoid false-positive diagnoses of severe GHD in obese adults.

Adult survivors of childhood acute lymphoblastic leukaemia with GH deficiency have normal self-rated quality of life but impaired neuropsychological performance 20 years after cranial irradiation

OBJECTIVE

Cranial radiotherapy (CRT) was, until recently, important for achieving long-term survival in acute lymphoblastic leukaemia (ALL). Because survival rates have improved markedly, the long-term complications, such as GH deficiency (GHD) and neuropsychological impairment, have become increasingly important.

DESIGN AND PATIENTS

The level of self-reported quality of life and neuropsychological functioning was investigated in 44 adults (21 women) with a median age of 25 years who had been treated for childhood onset (CO) ALL with CRT (median 24 Gy). Comparison was made with matched population controls. A subset of patients with GHD was evaluated for neuropsychological functioning after 1 year of GH treatment.

RESULTS

Compared to controls, the patients had significantly lower performance in neuropsychological tests. Early age at treatment had a significant negative impact on neuropsychological performance in adulthood. No relationship was found between dose of CRT, time since treatment of ALL or gender and neuropsychological performance. Compared to controls, the patients did not show a poor quality of life or a lowered availability of social interactions or social networks; however, significantly more patients were living alone or with their parents. After GH testing, the patients were all considered GH deficient or insufficient, but no relationship was observed between stimulated peak GH secretion and neuropsychological performance. Treatment with GH for 1 year in a subgroup of the patients did not improve their neuropsychological performance.

CONCLUSIONS

This study showed that adults treated with CRT for CO ALL had GHD and significantly impaired neuropsychological performance, although self-reported quality of life was not affected. The effect of GH treatment in this patient group has to be further elucidated.

Neurobehavioral and quality of life changes associated with growth hormone insufficiency after complicated mild, moderate, or severe traumatic brain injury

Adult-onset growth hormone deficiency (GHD) has been associated with reduced quality of life (QOL) and neurobehavioral (NB) deficits. This prospective study tested the hypothesis that traumatic brain injury (TBI) patients with GHD or GH insufficiency (GHI) would exhibit greater NB/QOL impairment than patients without GHD/GHI. Complicated mild, moderate, and severe adult TBI patients (GCS score 3-14) had pituitary function and NB/QOL testing performed 6-9 months postinjury. GH-secretory capacity was assessed with a GHRH-arginine stimulation test and GHD and GHI were defined as peak GH<6 or <or=12 ng/mL (5th and 10th percentiles of healthy control subjects, respectively). Of 44 patients (mean age, 32+/-18 years; median GCS, 7), one (2%) was GHD, seven (16%) were GHI, and 36 (82%) were GH-sufficient at 6-9 months post-injury. Mean peak GH was 8.2+/-2.1 ng/mL in the GHD/GHI group versus 45.7+/-29 ng/mL in the GHsufficient group. The two groups were well-matched in injury characteristics, except that one patient with GHD had central hypogonadism treated with testosterone prior to NB/QOL testing. At 6-9 months postinjury, patients with GHD/GHI had higher rates of at least one marker of depression (p<0.01), and reduced QOL (by SF-36 Health Survey) in the domains of limitations due to physical health (p=0.02), energy and fatigue (p=0.05), emotional well-being (p=0.02), pain (p=0.01), and general health (p=0.05). Chronic GHI develops in approximately 18% of patients with complicated mild, moderate, or severe TBI, and is associated with depression and diminished QOL. The impact of GH replacement therapy on NB function and QOL in these TBI patients is being tested in a randomized placebo-controlled trial.

Mutations within Sox2/SOX2 are associated with abnormalities in the hypothalamo-pituitary-gonadal axis in mice and humans

The transcription factor SOX2 is expressed most notably in the developing CNS and placodes, where it plays critical roles in embryogenesis. Heterozygous de novo mutations in SOX2 have previously been associated with bilateral anophthalmia/microphthalmia, developmental delay, short stature, and male genital tract abnormalities. Here we investigated the role of Sox2 in murine pituitary development. Mice heterozygous for a targeted disruption of Sox2 did not manifest eye defects, but showed abnormal anterior pituitary development with reduced levels of growth hormone, luteinizing hormone, and thyroid-stimulating hormone. Consequently, we identified 8 individuals (from a cohort of 235 patients) with heterozygous sequence variations in SOX2. Six of these were de novo mutations, predicted to result in truncated protein products, that exhibited partial or complete loss of function (DNA binding, nuclear translocation, or transactivation). Clinical evaluation revealed that, in addition to bilateral eye defects, SOX2 mutations were associated with anterior pituitary hypoplasia and hypogonadotropic hypogonadism, variable defects affecting the corpus callosum and mesial temporal structures, hypothalamic hamartoma, sensorineural hearing loss, and esophageal atresia. Our data show that SOX2 is necessary for the normal development and function of the hypothalamo-pituitary and reproductive axes in both humans and mice.

Hypopituitarism findings in patients with primary brain tumors 1 year after neurosurgical treatment: preliminary report

Hypopituitarism represents the consequence of many conditions, in both the adult and child population. It may occur after neurosurgical treatment of brain tumors arising near sella turcica. Much more attention has been focused on lesions far from the hypothalamic-pituitary region as possible causes of pituitary impairment, validating the concept of the particular fragility of these structures. The aim of this study was to evaluate pituitary function in particular GH deficiency (GHD) in patients submitted to neurosurgery for benign tumors of the central nervous system (CNS) not involving hypothalamic-pituitary region. We observed 37 patients with benign brain tumors [13 males, 24 females, age: 54.6+/-13.9 yr; body mass index (BMI): 25.1+/-4.0 kg/m2] performing a basic evaluation of the pituitary function and a dynamic test of the GH/IGF-I axis [GHRH (1 microg/kg iv)+arginine (0.5 g/kg iv) test] for 3 and 12 months after the neurosurgical treatment. Some degree of hypopituitarism was shown in 16 patients (43.2%) at the 3-months follow-up. Hypogonadism was present in 4 patients, hypoadrenalism in another 4 and hypothyroidism in 2. Two patients showed mild hyperprolactinemia and no patients had diabetes insipidus. Seven patients (18.9%) were GH deficient (peak GH <16.5 microg/dl). At 12 months retesting, some degree of hypopituitarism was confirmed in 8 patients, hypogonadism in 2 and hypothyroidism in one; no patients showed hypoadrenalism and GHD was present in 5. This data suggests that hypopituitarism of various degree may develop in patients who are submitted to neurosurgery for primary brain tumors, even far from hypothalamic-pituitary region.

Arginine challenge unravels persistent disturbances of urea cycle and gluconeogenesis in abstinent alcoholics

AIMS

Data on recovery from hormonal and metabolic sequelae of alcoholism in strictly controlled alcohol abstinence are mainly restricted to short-term abstention. Our previous findings of persistently decreased plasma and urinary urea concentrations in long-term abstinent alcoholics prompted us to further elucidate this unexplained phenomenon.

METHODS

The response of circulating urea cycle metabolites and glucose-regulating hormones to an intravenous load (30 g) of arginine hydrochloride was investigated in abstinent male alcoholics (n = 14) after complete recovery of all routine liver parameters and compared with that in healthy male controls (n = 15).

RESULTS

The arginine challenge provoked (i) higher peak concentrations of arginine and increased arginine/ornithine and ornithine/citrulline ratios in the plasma of abstinent alcoholics; (ii) augmented plasma glutamine concentrations in alcoholics in the presence of comparable levels in both experimental groups of plasma glutamate, ammonia, and nitrate/nitrite; (iii) parallel increases in plasma urea concentrations over the respective baseline levels but distinctly higher urinary urea excretion in controls; (iv) a blunted blood glucose response to arginine in alcoholics together with a reduced insulin and glucagon surge; and (v) an elevated growth hormone peak as compared with controls.

CONCLUSIONS

Application of an intravenous arginine challenge reveals profound and lasting metabolic and hormonal disturbances in abstinent alcoholics, affecting urea cycle and gluconeogenesis. The common denominator of many of these changes may be an acquired irreversible deficiency in cellular energy regulation.

Diagnosis of adult growth hormone deficiency: still a matter of debate

The diagnosis of GH deficiency (GHD) in adults is established by laboratory testing in patients with an appropriate clinical history of hypothalamic pituitary disease. As the measurement of IGF-I and IGFBP-3 levels as well as the spontaneous GH secretion are not considered reliable parameters, the diagnosis of GHD in adults may be established by GH provocative tests, provided that a reproducible test with clear normative limits is available. The insulin tolerance test (ITT) is a reliable diagnostic test in adults, but is contraindicated in several clinical conditions which are often observed in adult patients with suspected GHD. The other classic GH provocative tests, except the glucagon test, have a poor diagnostic utility and should be abandoned. GHRH combined with arginine or GH secretagogues represent a potent, safe, reproducible and reliable test which should be preferable to the ITT as a first-choice diagnostic test for GHD.

Metabolic syndrome and growth hormone deficiency in adult survivors of childhood acute lymphoblastic leukemia

BACKGROUND

The purpose of the study was to determine the prevalence of metabolic syndrome, growth hormone deficiency, and cardiovascular risk factors among adult survivors of childhood acute lymphoblastic leukemia (ALL) treated with or without cranial irradiation.

METHODS

Follow-up was undertaken of 75 randomly selected long-term childhood ALL survivors. Testing included fasting insulin, glucose, lipids, and growth hormone (GH) releasing hormone plus arginine stimulation test. The prevalence of metabolic syndrome was compared with population norms from 1999-2002 National Health and Nutrition Examination Study (NHANES) data, and internally between those with and without past cranial irradiation and those with normal (>16.5 microg/L) versus insufficient (9-16.5 microg/L) versus deficient (<9 microg/L) peak GH secretion.

RESULTS

The mean subject age was 30 years and the mean time since ALL diagnosis was 25 years. The prevalence of metabolic syndrome did not differ statistically (P = .87) between study subjects (16.6%) and same-age, same-sex population norms (17.5%). However, 60% of subjects treated with cranial irradiation, compared with 20% of those who were not, had 2 or more of the 5 components of metabolic syndrome. Untreated abnormally low GH was present in 64% of subjects overall and 85% of those who received past cranial irradiation. Cranial irradiation was strongly related to GH deficiency, and in turn lower insulin-like growth factor 1 (IGF-1), higher fasting insulin, abdominal obesity, and dyslipidemia, particularly in women.

CONCLUSIONS

Hematologists who treat childhood ALL patients, and particularly those who provide primary care to adult survivors, should be aware of the potential for long-term GH deficiency and adverse cardiovascular and diabetes risk profiles as a consequence of leukemia treatment.

Consensus guidelines on screening for hypopituitarism following traumatic brain injury

PRIMARY OBJECTIVE

The goal of this consensus statement is to increase awareness among endocrinologists and physicians treating patients with traumatic brain injury (TBI) of the incidence and risks of hypopituitarism among patients with TBI.

RATIONALE

TBI poses significant risk to the pituitary gland, leading to elevated risks of diabetes, hypopituitarism and other endocrinopathies. Signs and symptoms associated with hypopituitarism often mimic the sequellae of TBI, although the severity of symptoms is not necessarily related to the severity of the injury. Patients with TBI-induced hypopituitarism may benefit both physically and psychologically from appropriate hormone replacement therapy (HRT). Participants at this unique consensus meeting attempted to define and spearhead an approach to increase awareness of the risks of TBI-induced endocrinopathies, in particular growth hormone deficiency (GHD), and to outline necessary and practical objectives for managing this condition.

RECOMMENDATIONS

Systematic screening of pituitary function is recommended for all patients with moderate-to-severe TBI at risk of developing pituitary deficits. Patients with hypopituitarism benefit from appropriate hormonal replacement and prospects for rehabilitation of patients with TBI-induced hypopituitarism may be enhanced by appropriate HRT. Further exploration of this possibility requires: (1) active collaboration between divisions of endocrinology and rehabilitation at the local level to perform a screening of pituitary function in patients after TBI, (2) creation of a consultancy service by endocrine societies for use by rehabilitation centres, (3) development of continuing medical education (CME) programmes that can be offered as crossover training to the physicians who manage the care of patients with TBIs, (4) targeting of patient organizations with educational information for dissemination to patients and their families, (5) continued efforts to more clearly define the population at greatest risk of TBI-induced hypopituitarism and (6) monitor results of efficacy studies as they become available to evaluate whether and how much replacement therapy can improve the symptoms of individuals with TBI-induced hypopituitarism.