The diagnosis of growth hormone deficiency (GHD) in successfully treated acromegalic patients

In patients with controlled acromegaly, indices of glucose homeostasis correlate with IGF-1 levels rather than with type of treatment

OBJECTIVE

Acromegaly is accompanied by abnormalities in glucose and lipid metabolism which improve upon treatment. Few studies have investigated whether these improvements differ between treatment modalities. This study aimed to compare glucose homeostasis, lipid profiles and postprandial gut hormone response in patients with controlled acromegaly according to actual treatment.

DESIGN

Cross-sectional study at a tertiary care centre.

PATIENTS

Twenty-one patients with acromegaly under stable control (ie insulin growth factor 1 [IGF1] levels below sex- and age-specific thresholds and a random growth hormone level <1.0 µg/L) after surgery (n = 5), during treatment with long-acting somatostatin analogues (n = 10) or long-acting somatostatin analogues + pegvisomant (n = 6) were included.

MEASUREMENTS

Glucose, insulin, total cholesterol and high-density lipoprotein-cholesterol were measured in fasting serum samples. Glucose, insulin, triglycerides, glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1 were measured during a mixed meal test. Insulin sensitivity was evaluated by a hyperinsulinaemic-euglycaemic clamp.

RESULTS

There were no significant differences in glucose tolerance, insulin sensitivity or postprandial gut hormone responses between the three groups. Positive correlations between IGF1 levels and HbA1c, fasting glucose and insulin levels and postprandial area under the curve (AUC) of glucose and insulin and also an inverse association between IGF1 and glucose disposal rate were found in the whole cohort (all p < .05, lowest p = .001 for postprandial AUC glucose with r_s  = 0.660).

CONCLUSION

In this cross-sectional study in patients with controlled acromegaly, there were no differences in glucose homeostasis or postprandial substrate metabolism according to treatment modality. However, a lower IGF1 level seems associated with a better metabolic profile.

Dynamic Ghrelin and GH serum levels during combined simultaneous arginine clonidine stimulation test in children with dwarfism

Background

Combined simultaneous arginine clonidine stimulation (CSACS) test represents a more appropriate stimulus to detect Ghrelin, for it does not affect glucose metabolism.

Methods

Fifty prepubertal children with dwarfism were recruited and further classified into normal growth hormone (NGH) and growth hormone deficiency (GHD) group with growth hormone (GH) peak cut-off value of 10 μg/l. In both groups, GH and Ghrelin serum levels were determined after the GH provocation test at 30, 60, and 120 min and the height standard deviation score (SDS) for bone age was measured six months later.

Results

The participants were classified into NGH (n = 24) and GHD group (n = 26). A decrease in the circulating Ghrelin levels prior to the GH peak was observed in the NGH children, whereas both GH and Ghrelin levels demonstrated a rise in the GHD children. Ghrelin level in GHD group was higher compared with NGH group and the GH peak in GHD group is lower than NGH group. The 6 months CSACS treatment could increase the height SDS in both groups.

Conclusion

Although analogous changes were not detected in GHD group, the inverse correlation between GH and Ghrelin in NGH indicates a negative feedback lying between GH and Ghrelin.

Growth hormone deficiency in treated acromegaly and active Cushing's syndrome

Growth hormone deficiency (GHD) in adults is characterized by reduced quality of life and physical fitness, skeletal fragility, increased weight and cardiovascular risk. It may be found in (over-) treated acromegaly as well as in active Cushing's syndrome. Hypopituitarism may develop in patients after definitive treatment of acromegaly, although the exact prevalence of GHD in this population is still uncertain because of limited awareness, and scarce and conflicting data so far available. Because GHD associated with acromegaly and Cushing's syndrome may yield adverse consequences on similar target systems, the final outcomes of some complications of both acromegaly and Cushing's syndrome may be further affected by the occurrence of GHD. It is still largely unknown, however, whether GHD in patients with post-acromegaly or active Cushing's syndrome (e.g. pharmacologic glucocorticoid treatment) may benefit from GH replacement. We review the diagnostic, clinical and therapeutic aspects of GHD in adults treated for acromegaly and in those with active Cushing's syndrome.

Surgery induced hypopituitarism in acromegalic patients: a systematic review and meta-analysis of the results

PURPOSE

Hypopituitarism is a possible complication of the surgical treatment of acromegaly. However, there is a wide variability in the incidence rates of surgery-induced hypopituitarism. The purpose of this study was the systematic collection and synthesis of information on the incidence rates of hypopituitarism, panhypopituitarism, specific axis deficiencies and diabetes insipidus after surgery for acromegaly treatment.

METHODS

We systematically reviewed all the papers that have reported pituitary deficits after surgery for acromegaly published up until December 2014, in the PubMed database. We identified 92 studies enrolling 6988 patients. A meta-analysis was performed to evaluate the incidence rates. We also performed several subgroup analyses to evaluate the impact of both surgical technique, and treatment prior to surgery, on the results.

RESULTS

The weighted incidence rates were 12.79 % for hypopituitarism (95 % CI 9.88-16.00 %), 2.50 % for panhypopituitarism (95 % CI 1.24-4.15 %), 6.50 % for ACTH deficiency (95 % CI 4.07-9.44 %), 4.39 % for TSH deficiency (95 % CI 2.99-6.04 %), 6.70 % for FSH/LH deficiency (95 % CI 3.89-10.17 %), 14.95 % for GH deficiency (95 % CI 7.25-24.64 %), 10.05 % for transient (95 % CI 7.18-13.33 %) and 2.42 % for permanent diabetes insipidus (95 % CI 1.70-3.27 %).

CONCLUSION

Our study provides new data on the incidence rates of hypopituitarism, specific pituitary axis deficiencies and diabetes insipidus after surgical treatment of acromegaly. Somatotroph function appears to be more prone to deficit than the other axes. However, there is a high heterogeneity between studies and several factors may influence the incidence of hypopituitarism.

Bone turnover, bone mineral density, and fracture risk in acromegaly: a meta-analysis

CONTEXT

GH excess causes an increase in bone turnover, but the consequences in terms of skeletal fragility have long been uncertain due to the heterogeneity of studies dealing with this topic.

OBJECTIVE

We conducted a meta-analysis of studies examining the effects of acromegaly on bone turnover, bone mineral density (BMD), and fractures. Furthermore, we evaluated the effects of sex, gonadal status, and activity of disease on skeletal end-points in acromegaly.

DATA SOURCES

We conducted MEDLINE and EMBASE systematic searches up to December 31, 2013.

STUDY ELIGIBILITY CRITERIA

Studies conducted in patients with acromegaly and reporting at least one determinant of skeletal fragility.

DATA EXTRACTION AND ANALYSIS

Study design, patient characteristics, interventions, and outcomes were independently extracted by two authors. We calculated the standardized mean difference (SMD) of bone turnover and BMD differences, whereas fractures were presented as relative frequencies in acromegaly and odds ratios between patients and controls.

RESULTS

Forty-one studies fulfilled eligibility criteria and were therefore selected for data extraction and analysis. A total of 1935 patients were included (eight to 206 per study). Acromegaly patients had higher bone formation (SMD, 1.49; 95% confidence interval [CI], 0.97-2.01; P < .0001) and bone resorption (SMD, 1.57; 95% CI, 1.03-2.10; P < .0001) as compared to control subjects, without significant differences in lumbar spine BMD. BMD at the femoral neck tended to be higher in acromegaly patients vs control subjects (SMD, 0.67; 95% CI, 0.07-1.27; P = .03). Patients with acromegaly had high frequency of vertebral fractures (odds ratio, 8.26; 95% CI, 2.91-23.39; P < .0001), in close relationship with male gender, hypogonadism, and active acromegaly.

LIMITATIONS

LIMITATIONS included heterogeneous study protocols with possible variability in the assessment of skeletal end-points.

CONCLUSIONS

Skeletal fragility is an emerging complication of acromegaly.

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.

Effects of long-term growth hormone replacement in adults with growth hormone deficiency following cure of acromegaly: a KIMS analysis

CONTEXT

GH deficiency (GHD) may occur in adults with cured acromegaly (acroGHD).

OBJECTIVE

Our objective was to examine the effectiveness and safety of GH replacement in acroGHD.

DESIGN

This study was a retrospective analysis of data from KIMS (Pfizer International Metabolic Database).

SETTING

Data were extracted from a pharmaco-epidemiological survey of >16 000 GHD adults from 31 countries.

PATIENTS

The effectiveness population included 115 adults with acroGHD and 142 age-, gender-, and body mass index-matched GHD adults with nonfunctioning pituitary adenoma (NFPA) followed up to 5 years on GH. The safety population included 164 adults with acroGHD and 2469 with NFPA, all GH-replaced. Both acroGHD and NFPA were compared with several cohorts from the general population (including the World Health Organization Global Burden of Disease).

OUTCOME MEASURES

Outcome measures included quality of life (QoL-AGHDA), lipids, serious adverse events, and additional safety endpoints.

RESULTS

Median GH dose was 0.3 mg/d in acroGHD and NFPA at 5 years. There were comparable improvements in QoL-AGHDA and total and low-density lipoprotein cholesterol in acroGHD and NFPA. High-density lipoprotein cholesterol increased only in acroGHD. Cardiovascular mortality was increased in acroGHD vs NFPA (standardized mortality ratio = 3.03, P = .02). All-cause mortality was similar in acroGHD (ratio between observed/expected cases [95% confidence interval] = 1.32 [0.70-2.25]) and lower in NFPA [observed/expected = 0.58 [0.48-0.70]) in comparison with the general population. There was no difference in incidence of all cancers, benign or malignant brain tumors, or diabetes mellitus between acroGHD and NFPA.

CONCLUSIONS

GH replacement has comparable effects on quality of life and lipids in acroGHD and NFPA. Further investigation is needed to examine whether the increased cardiovascular mortality may be attributed to the history of previous GH excess in acroGHD.

Reevaluation of Acromegalic Patients in Long-Term Remission according to Newly Proposed Consensus Criteria for Control of Disease

Acromegaly guidelines updated in 2010 revisited criteria of disease control: if applied, it is likely that a percentage of patients previously considered as cured might present postglucose GH nadir levels not adequately suppressed, with potential implications on management. This study explored GH secretion, as well as hormonal, clinical, neuroradiological, metabolic, and comorbid profile in a cohort of 40 acromegalic patients considered cured on the basis of the previous guidelines after a mean follow-up period of 17.2 years from remission, in order to assess the impact of the current criteria. At the last follow-up visit, in the presence of normal IGF-I concentrations, postglucose GH nadir was over 0.4 μg/L in 11 patients (Group A) and below 0.4 μg/L in 29 patients (Group B); moreover, Group A showed higher basal GH levels than Group B, whereas a significant decline of both GH and postglucose GH nadir levels during the follow-up was observed in Group B only. No differences in other evaluated parameters were found. These results seem to suggest that acromegalic patients considered cured on the basis of previous guidelines do not need a more intensive monitoring than patients who met the current criteria of disease control, supporting instead that the cut-off of 0.4 mcg/L might be too low for the currently used GH assay.

Severe growth hormone deficiency is rare in surgically-cured acromegalics

Growth hormone deficiency (GHD) in surgically-cured acromegalics has been reported to negatively affect their metabolic condition and quality of life (QOL). The incidence of GHD, its causes, and its effects on their physio-psychological condition remain to be examined in detail. We performed a retrospective study to investigate GH secretory function in surgically-cured acromegalics, prognostic factors of GHD, and its impact on QOL. The study population consisted of 72 acromegalics who were determined to be surgically cured according to the Cortina consensus criteria. We recorded the incidence of impaired GH secretory function based on the peak GH level during postoperative insulin tolerance test (ITT) which lowered their nadir blood sugar to under 50 mg/dL. Their QOL was evaluated by SF-36. In surgically-cured acromegalics, the incidence of severe GHD (peak GH during ITT ≦ 3.0 μg/L) was 12.5 % (9/72). The preoperative tumor size was significantly larger in patients with severe GHD than without severe GHD (21.9 ± 9.0 vs. 15.5 ± 7.1 mm, p = 0.017). The peak GH levels during postoperative ITT were statistically correlated with the physical but not the mental component summary of the SF-36 score. The incidence of GHD was 12.5 % in our surgically-cured acromegalics. As some QOL aspects are positively related with peak GH levels during postoperative ITT, efforts should be made to preserve pituitary function in acromegalic patients undergoing adenomectomy.

Clinical features and therapeutic outcomes of patients with acromegaly: single-center experience

The aim of this study was to review the outcome of acromegaly treatment, as well as co-morbidity and mortality in a series of patients with acromegaly attending a single center in the last 10 yr. In that period, 53 patients were treated for acromegaly. Transsphenoidal operation was applied as the first-line therapy in 94.3% of patients and it led to disease remission in 59.2% of them. The remission criteria included a nadir GH<1 μg/l after glucose load, and normal age-related IGF-I levels. The remission rate after transsphenoidal surgery was significantly higher in the group of patients with microadenoma (76.9%), than in the group of patients with macroadenoma (52.8%). Patients with invasive tumors had remission rate of 16.7% after transsphenoidal surgery. There were no perioperative deaths. As the second-line treatment somatostatin analogues, radiotherapy, and dopaminergic agonists were used. Hypertension and diabetes were the most frequent co-morbidities in the group of patients. After successful treatment, 30% of patients with diabetes or impaired glucose tolerance had significant improvement of glycemic control. Transsphenoidal surgery is the appropriate firstline therapy in patients with somatotropinoma. Medical and radio-therapy should be reserved as the second-line therapy after surgery failure.

The accuracy of diagnostic tests for GH deficiency in adults: a systematic review and meta-analysis

CONTEXT

The diagnostic accuracy of tests used to diagnose GH deficiency (GHD) in adults is unclear.

OBJECTIVE

We conducted a systematic review and meta-analysis of studies that provided data on the available diagnostic tests.

DATA SOURCES

We searched electronic databases (MEDLINE, EMBASE, Cochrane CENTRAL, Web of Sciences, and Scopus) through April 2011.

STUDY SELECTION

Review of reference lists and contact with experts identified additional candidate studies. Reviewers, working independently and in duplicate, determined study eligibility.

DATA EXTRACTION

reviewers, working independently and in duplicate, determined the methodological quality of studies and collected descriptive, quality, and outcome data.

DATA SYNTHESIS

Twenty-three studies provided diagnostic accuracy data; none provided patient outcome data. Studies had fair methodological quality, used several reference standards, and included over 1100 patients. Several tests based on direct or indirect stimulation of GH release were associated with good diagnostic accuracy, although most were assessed in one or two studies decreasing the strength of inference due to small sample size. Serum levels of GH or IGF1 had low diagnostic accuracy. Pooled sensitivity and specificity of the two most commonly used stimulation tests were found to be 95 and 89% for the insulin tolerance test and 73 and 81% for the GHRH+arginine test respectively. Meta-analytic estimates for accuracy were associated with substantial heterogeneity.

CONCLUSION

Several tests with reasonable diagnostic accuracy are available for the diagnosis of GHD in adults. The supporting evidence, however, is at high risk of bias (due to heterogeneity, methodological limitations, and imprecision).

GH deficiency in patients after cure of acromegaly by surgery alone

OBJECTIVE

The aim of this study was to determine the frequency and characteristics of severe GH deficiency (sGHD) in patients after treatment of acromegaly by surgery alone.

DESIGN AND METHODS

One hundred and eighty-six patients fulfilling the criteria for cure of acromegaly were examined by GH-releasing peptide-2 stimulation test or arginine stimulation test as well as oral glucose tolerance test (GTT). In addition, the Japanese adult hypopituitarism questionnaire was completed to determine the quality of life (QoL).

RESULTS

sGHD was found in 17 patients (9.1%; the GH-deficient group), and not found in 169 patients (90.9%; the GH-sufficient group). There were no significant differences in preoperative serum GH levels, IGF1 levels, incidence of hyperprolactinemia, tumor volumes, or incidence of microadenoma between the two groups. Upon follow-up examination, IGF1 levels and Z-scores of IGF1 levels were significantly lower in the GH-deficient group than in the GH-sufficient group, whereas neither basal GH levels nor nadir GH levels during 75 g GTT were significantly different between the two groups. Moreover, sGHD patients had a substantially higher incidence of multiple pituitary failures (17.6 vs 2.4%) and dyslipidemia (60 vs 16.2%). sGHD patients had a substantially poorer condition-related QoL.

CONCLUSIONS

This is the first large-scale, single-center, clinical study to evaluate sGHD in patients after cure of acromegaly by surgery alone. This study found that sGHD occurred in ~9% of patients and assessment of GHD by stimulation tests is critical after successful treatment of acromegaly by surgery.

Growth hormone deficiency after treatment of acromegaly: a randomized, placebo-controlled study of growth hormone replacement

CONTEXT

The effects of GH replacement therapy in patients who develop GH deficiency (GHD) after cure of acromegaly have not been established in a placebo-controlled study.

OBJECTIVE

The objective of the study was to determine whether GH replacement improves body composition, cardiovascular risk markers and quality of life in patients with GHD and prior acromegaly.

DESIGN

This was a 6-month, randomized, placebo-controlled study.

SETTING

The study was conducted at a clinical translational science center.

STUDY PARTICIPANTS

Participants included 30 subjects with prior acromegaly and current GHD.

INTERVENTION

INTERVENTIONs included GH or placebo.

MAIN OUTCOME MEASURES

Body composition (dual-energy x-ray absorptiometry and cross-sectional computed tomography at L4), cardiovascular risk markers (high-sensitivity C-reactive protein (hsCRP), total, high-density lipoprotein and low-density lipoprotein cholesterol, fibrinogen, and carotid intimal-medial thickness), and quality of life were measured.

RESULTS

The mean GH dose at 6 months was 0.58 +/- 0.26 mg/d. Total fat mass, visceral adipose tissue (-15.3 +/- 18.6 vs. 1.3 +/- 12.5%, P = 0.01), and total abdominal fat decreased, and fat-free mass increased, in the GH vs. placebo group. Mean hsCRP levels decreased, but there was no GH effect on other cardiovascular risk markers. There was no change in glycosylated hemoglobin or homeostasis model assessment insulin resistance index. Quality of life improved with GH. Side effects were minimal.

CONCLUSIONS

This is the first randomized, placebo-controlled study of the effects of GH replacement therapy on body composition and cardiovascular end points in patients who have developed GH deficiency after treatment for acromegaly, a disease complicated by metabolic and body composition alterations and increased cardiovascular risk. GH replacement decreased visceral adipose tissue, increased fat-free mass, decreased hsCRP, and improved quality of life in patients with GHD after cure of acromegaly, with minimal side effects and without an increase in insulin resistance.

Safety of GH replacement in hypopituitary patients with nonirradiated pituitary and peripituitary tumours

BACKGROUND

Published data suggest that growth hormone replacement (GHR) may be given safely to patients with hypopituitarism consequent upon a pituitary/peripituitary tumour. However, a preponderance of patients treated with external pituitary irradiation were included.

OBJECTIVE

To assess the safety of GHR in nonirradiated pituitary/peripituitary tumour.

DESIGN

Prospective audit.

SETTING

Tertiary university referral centre.

PATIENTS

We imaged prospectively the pituitary glands of 48 patients (18 males; mean age 51.6 years range 21-77) who had adult onset growth hormone deficiency (AO-GHD) after appropriate treatment for a pituitary/peripituitary tumour but who did not receive external pituitary irradiation.

INTERVENTION

All patients were treated with a dose titration regimen of GH to maintain serum IGF-1 between the median and upper end of the age-related reference range. Pituitary surveillance imaging was performed prior to the commencement of GHR, at 6-12 months and then yearly. For patients with secretory tumours, biochemical markers (cortisol and prolactin) were used as evidence of tumour recurrence.

RESULTS

48 patients with median follow up since commencement of GHR was 38 months (range 9-104). Three patients were judged to have an apparent increase in tumour volume and/or marker, although only one was thought to be possibly GH related--a patient with a cystic chromophobe adenoma who demonstrated a marginal increase in residual tumour volume 4 years after commencement of GHR.

CONCLUSION

These data add to the growing body of evidence for the safety of GHR in hypopituitary patients consequent upon pituitary/peripituitary mass lesions and represents the first reported series in a heterogeneous group of nonirradiated patients.

Adequacy of current postglucose GH nadir limit (< 1 microg/l) to define long-lasting remission of acromegalic disease

OBJECTIVE

Some authors proposed to lower the present postglucose GH nadir cut-off (i.e. < 1 microg/l) to that obtained in healthy subjects to establish remission of acromegaly. The aim of the study was to correlate GH nadir with hormonal and metabolic parameters and to confirm the adequacy of the current limit to define disease remission.

DESIGN AND PATIENTS

Retrospective study of 40 acromegalic patients cured by surgery, followed by radiotherapy when appropriate, studied at the time of disease remission (Phase 1) and re-evaluated after at least 3 years' follow-up (median 6.5 year, Phase 2). GH nadir was evaluated in 44 sex- and age-matched controls.

MEASUREMENTS

Symptom score, pituitary function, neuroradiological imaging, metabolic parameters (BMI, glucose metabolism, insulin sensitivity, lipid profile, blood pressure).

RESULTS

The upper limit of the 'normal' GH nadir was fixed at 0.26 microg/l (mean + 2SD of controls). In Phase 1, GH nadir was < 0.26 microg/l in 16 patients (Group A) and > 0.26 microg/l in 24 patients (Group B). Group B had only slightly higher IGF-1 SDS (0.4 +/- 1.0 vs.- 0.1 +/- 1.0, P = ns) and lower body mass index (BMI) than Group A (26.2 +/- 2.4 vs. 30.6 +/- 4.5 kg/m(2), P < 0.005). GH nadir positively correlated with IGF-1 (P < 0.05, r = 0.32) and negatively with BMI (P < 0.05, r = 0.42). In Phase 2, all patients had IGF-1 levels in the normal range and GH nadir < 1 microg/l, both parameters being even lower than those found at the time of remission. No patient had either clinical or neuroradiological evidence of disease recurrence.

CONCLUSIONS

The current GH nadir limit is still adequate to define both short- and long-lasting remission of acromegaly, independently of the type of definitive treatment. Patients with the lowest GH nadir should probably be monitored long-term for adequacy of their GH secretion.

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.

Aetiology, diagnosis, and management of hypopituitarism in adult life

Hypopituitarism is a complex medical condition associated with increased morbidity and mortality, requires complicated treatment regimens, and necessitates lifelong follow up by the endocrinologist. The causes, clinical features, and the management of hypopituitarism including endocrine replacement therapy are considered in this review article.

The long-term efficacy of conventional radiotherapy in patients with GH-secreting pituitary adenomas

OBJECTIVE

To assess the long-term efficacy and safety of conventional radiotherapy (RT) in the control of acromegaly according to recent stringent criteria of cure.

DESIGN

A retrospective longitudinal study.

PATIENTS AND METHODS

Forty-seven patients with active acromegaly were treated with conventional RT between 1982 and 1994. All patients were first operated on and successively irradiated at a dose of 45-50 Gy in 25-28 fractions for persistent (n = 40) or recurrent (n = 7) disease.

MEASUREMENTS

Long-term GH/IGF-I secretion and local tumour control were evaluated regularly, and possible side-effects were searched for systematically, especially in terms of secondary endocrine dysfunction. Biochemical cure of acromegaly was defined by glucose-suppressed plasma GH levels below 1 microg/l during an oral glucose tolerance test (OGTT) and normal age-corrected IGF-I values.

RESULTS

The 5-, 10- and 15-year overall survival rates were 98%, 95% and 93%, respectively. Suppression of GH during OGTT was seen in 9% of patients at 2 years, 29% at 5 years, 52% at 10 years, and 77% at 15 years. Age-corrected IGF-I levels were normal in 8% of patients 2 years after RT, and this proportion increased to 23%, 42% and 61% after 5, 10 and 15 years, respectively. Normalization of GH/IGF-I mainly depended on pre-RT levels. Local tumour control was 95% at 5, 10 and 15 years after treatment. Late toxicity was mainly represented by progressive hypopituitarism, which was present in 33% of patients at baseline and increased to 57%, 78% and in 85% of patients at 5 10 and 15 years after RT, respectively.

CONCLUSION

Conventional RT is effective in the long-term control of GH-secreting pituitary adenomas, although with a high prevalence of progressive hypopituitarism. At present, it remains a suitable option in acromegalic patients uncontrolled by surgery or medical therapy.

Evaluation of growth hormone stimulation tests in cured acromegalic patients

We have evaluated the GH peak response to insulin tolerance test (ITT) and to GHRH+arginine in 11 patients cured of acromegaly after treatment with surgery/radiotherapy and compared them to a control group matched for age and sex. GH peak response was significantly higher in the control group than in the patient group (11.21+/-6.98 vs. 4.46+/-6.90 ng/ml, p=0.010). Seven patients had a GH peak response of less than 3 ng/ml, compatible with the diagnosis of GH deficiency. Peak GH response after GHRH+arginine was significantly lower in the group of patients with GH peak of less than 3 ng/ml during ITT as compared to the group with GH peak of more than 3 ng/ml, and in all cases the diagnosis of GH deficiency was confirmed. Mean IGF-I level was not different between the patients and controls, as well as between patients with and without GH deficiency diagnosed by the stimulation tests.

CONCLUSION

The incidence of GHD diagnosed by stimulation tests is high in patients cured of acromegaly.

Optimizing Somatostatin Analog Therapy in Acromegaly

Somatostatin peptide analogs have revolutionized the medical treatment of patients with acromegaly. More recent deep intramuscular depot preparations have further improved control, with consistent suppression of growth hormone secretion and optimal lowering of insulin-like growth factor-1. Effective control of growth hormone should, with long-term use, reduce morbidity and mortality from acromegaly and has been shown to result in partial involution of the pituitary adenoma in the majority of treated patients. The currently available depot formulations allow for an injection frequency of 14 days (lanreotide LA 30mg) to 28 days (octreotide LAR 20mg) according to the manufacturers' recommendations. In clinical practice, dose titration by evaluating a growth hormone day profile prior to the next injection can extend the interval between injection (to 6 or even 8 weeks in certain individuals). This is especially true for octreotide LAR, which also has increased flexibility regarding dosage with a 10 and 30mg preparation. The annual 'drug cost' is broadly similar between the two formulations though the additional expenditure on nurse time and clinic visits incurred by an increased injection frequency is a significant consideration. Decreased injection frequency improves acceptability for the patient without a loss in treatment efficacy. A subjective return of typical acromegalic symptoms, such as sweating and headache, also seem to be useful in predicting the timing of the next injection. Other formulations and doses of lanreotide are currently being evaluated, but more interestingly, newer analogs with greater efficacy at the type 5 somatostatin receptor subtype, and pan-receptor analogs, are being developed. These peptides, in conjunction with the likely availability of a growth hormone receptor blocking agent (pegvisomant), will further expand the medical therapy options for patients with acromegaly.