Diagnostic efficiency of serum IGF-I, IGF-binding protein-3 (IGFBP-3), IGF-I/IGFBP-3 molar ratio and urinary GH measurements in the diagnosis of adult GH deficiency: importance of an appropriate reference population

Association between serum insulin-like growth factor 1 levels and the improvements of cognitive impairments in a subgroup of schizophrenia: Preliminary findings

BACKGROUND

Numerous studies have implicated abnormal insulin-like growth factor 1 (IGF-1) in the pathophysiology of schizophrenia, but findings have been inconsistent.

METHODS

We conducted a meta-analysis to compare IGF-1 levels in schizophrenia patients with healthy controls and explored factors contributing to variability between estimates. In an independent sample (58 chronic schizophrenia patients and 30 healthy controls), we investigated differences in IGF-1 levels among schizophrenia subgroups with distinct cognitive profiles, identified using k-means clustering based on five cognitive domains from The Repeatable Battery for the Assessment of Neuropsychological Status. Associations between serum IGF-1 levels and clinical and neurocognitive improvements were also examined.

RESULTS

The meta-analysis revealed significantly lower serum IGF-1 levels in schizophrenia patients compared to healthy controls, albeit with high heterogeneity. Medication status, BMI, and severity of negative symptoms were identified as potential contributors to this heterogeneity. In our independent study, antipsychotic treatment led to a significant increase in IGF-1 levels, and lower pre-treatment serum IGF-1 levels correlated with greater improvement in cognitive deficits, particularly in a subgroup with more severe cognitive symptoms.

CONCLUSIONS

Our findings support the "IGF-1 deficiency hypothesis" in the pathogenesis of schizophrenia. Further research is crucial to elucidate the role of IGF-1 in the cognitive impairments associated with schizophrenia.

Serum IGF-1 to IGFBP-3 Molar Ratio: A Promising Diagnostic Tool for Growth Hormone Deficiency in Children

BACKGROUND

The serum insulin-like growth factor-1 (IGF-1)/insulin-like growth factor binding protein-3 (IGFBP-3) ratio has various potential applications in growth hormone-related disorders. This study aimed to investigate the performance of the IGF-1/IGFBP-3 ratio, independently and in combination with serum IGF-1 and IGFBP-3, in the diagnosis of growth hormone deficiency (GHD) in children with short stature (SS).

METHODS

A 7-year cross-sectional observational study was conducted on 235 children with SS. Participants with known disorders that may affect IGF-1 other than GHD were excluded. Participants were classified into GHD (n = 64) and non-GHD (n = 171) groups. GHD was defined as a slow growth rate (<25th percentile over 1 year) and suboptimal growth hormone (GH) response to 2 GH stimulation tests (peak GH < 6.25 ng/mL using the DiaSorin Liaison assay). The sensitivity and specificity of serum IGF-1, IGFBP-3, and IGF-1/IGFBP-3 molar ratio, independently and in various combinations, were determined.

RESULTS

GHD was diagnosed in 27.2% of participants. Among all studied variables, a low serum IGF-1/IGFBP-3 ratio demonstrated the greatest sensitivity for GHD (87.5%), with a comparable specificity (83.0%). The combination of low serum IGF-1, IGFBP-3, and IGF-1/IGFBP-3 ratio demonstrated the greatest specificity for GHD (97.7%), whereas the combination of normal serum IGF-1, IGFBP-3, and IGF-1/IGFBP-3 ratio demonstrated the greatest specificity for a non-GHD cause of SS (100.0%).

CONCLUSION

Our data suggest that the serum IGF-1/IGFBP-3 ratio is a useful marker for the diagnosis of GHD in children who do not have other disorders that may affect serum IGF-1 levels. Further large studies are needed to confirm the diagnostic utility of the serum IGF-1/IGFBP-3 ratio.

Development of a Novel Algorithm to Identify People with High Likelihood of Adult Growth Hormone Deficiency in a US Healthcare Claims Database

OBJECTIVE

Adult growth hormone deficiency (AGHD) is an underdiagnosed disease associated with increased morbidity and mortality. Identifying people who may benefit from growth hormone (GH) therapy can be challenging, as many AGHD symptoms resemble those of aging. We developed an algorithm to potentially help providers stratify people by their likelihood of having AGHD.

DESIGN

The algorithm was developed with, and applied to, data in the anonymized Truven Health MarketScan® claims database. Patients. A total of 135 million adults in the US aged ≥18 years with ≥6 months of data in the Truven database. Measurements. Proportion of people with high, moderate, or low likelihood of having AGHD, and differences in demographic and clinical characteristics among these groups.

RESULTS

Overall, 0.5%, 6.0%, and 93.6% of people were categorized into groups with high, moderate, or low likelihood of having AGHD, respectively. The proportions of females were 59.3%, 71.6%, and 50.4%, respectively. People in the high- and moderate-likelihood groups tended to be older than those in the low-likelihood group, with 58.3%, 49.0%, and 37.6% aged >50 years, respectively. Only 2.2% of people in the high-likelihood group received GH therapy as adults. The high-likelihood group had a higher incidence of comorbidities than the low-likelihood group, notably malignant neoplastic disease (standardized difference -0.42), malignant breast tumor (-0.27), hyperlipidemia (-0.26), hypertensive disorder (-0.25), osteoarthritis (-0.23), and heart disease (-0.22).

CONCLUSIONS

This algorithm may represent a cost-effective approach to improve AGHD detection rates by identifying appropriate patients for further diagnostic testing and potential GH replacement treatment.

Reference Ranges of Serum Insulin-Like Growth Factor-I and Insulin-Like Growth Factor Binding Protein-3: Results from a Multicenter Study in Healthy Korean Adults

Insulin-like growth factor-I (IGF-I) plays a pivotal role in the diagnosis and treatment of growth hormone (GH) excess or deficiency. The GH study group of the Korean Endocrine Society aims to establish the Korean reference ranges of serum IGF-I and insulin-like growth factor binding protein-3 (IGFBP-3) and assess the relationship between IGF-I and IGFBP-3 and clinical parameters. Fasting serum was collected from healthy Korean adults at health promotion centers of five hospitals nationwide. Serum IGF-I and IGFBP-3 were measured via an immunoradiometric assay using a DSL kit (Diagnostic Systems Laboratories). Serum samples from 354 subjects (180 male, 174 female) were analyzed based on sex at 10-year intervals from 21 to 70 years. IGF-I levels were inversely correlated with age. After adjustment of age, the IGF-I/IGFBP-3 ratio was significantly negatively associated with blood pressure and free thyroxine and positively associated with weight, hemoglobin, creatinine, alanine transferase, fasting glucose, and thyroid stimulating hormone. Therefore, age- and sex-specific reference ranges of serum IGF-I and IGFBP-3 can be efficient in evaluating GH excess or deficiency in Korean population.

IGF1 for the diagnosis of growth hormone deficiency in children and adolescents: a reappraisal

A number of studies have evaluated the role of IGF1 measurement in the diagnosis of growth hormone deficiency (GHD). This study aimed to evaluate the accuracy and the best cut-off of IGF1 SDS in the diagnosis of GHD in a large cohort of short children and adolescents. One-hundred and forty-two children and adolescents with GHD ((63 organic/genetic (OGHD), 79 idiopathic (IGHD)) and 658 short non-GHD children (median age 10.4 years) were included in the analysis. The two groups were subdivided according to age (G1 <6, G2 6 <9, G3 9 <12, G4 ≥12) and to pubertal status. Serum IGFI was measured by the same chemiluminescence assay in all samples and expressed as age- and sex-based SDS. Receiver operating characteristic (ROC) analysis was used to evaluate the optimal IGF1 SDS cut-off and the diagnostic accuracy. Median IGF1 SDS was significantly lower in the GHD than in non-GHD patients. The area under the curve (AUC) was 0.69, with the best IGF1 cut-off of -1.5 SDS (sensitivity 67.61%, specificity 62.62%). The AUC was 0.75 for OGHD and 0.63 for IGHD. The accuracy was better in the pubertal (AUC = 0.81) than the prepubertal group (AUC = 0.64). In our cohort, IGF1 measurement has poor accuracy in discriminating GHD from non-GHD. Our findings confirm and reinforce the belief that IGF1 values should not be used alone in the diagnosis of GHD but should be interpreted in combination with other clinical and biochemical parameters.

Evaluation of Safety and Efficacy of Growth Hormone Therapy by IGF-1 Z Score in Children with Short Stature

INTRODUCTION

This study aims to explore the safety and efficacy of growth hormone (GH) therapy by retrospectively analyzing the changes of insulin-like growth factor-1 (IGF-1) Z-scores in children with short stature after treatment with GH.

METHODS

The etiology of 104 children with short stature was classified according to the GH stimulation test and IGF-1 levels: (1) growth hormone deficiency (GHD); (2) mild growth hormone deficiency (M-GHD); (3) idiopathic short stature (ISS); (4) GH insensitivity syndrome (GHIS). In addition, all patients were treated with recombinant human growth hormone (rhGH) for 12 months, and the growth rate (Gv), height, body mass, bone age, height standard deviation scores (HtSDS), IGF-1 and adverse reactions were compared among these three groups before and after treatment.

RESULTS

The height, body mass, Gv and HtSDS were significantly higher in each group compared with those before treatment. Furthermore, the Z-score of IGF-1 significantly increased after 1 month of GH treatment and was positively correlated with the dosage of GH. Moreover, the difference in standard deviation score was significantly positively correlated with the increase in standard deviation score of IGF-1.

CONCLUSION

The detection of the GH-IGF-1 axis function can be carried out for the etiologic diagnosis of short stature. IGF-1 increased after rhGH treatment, and IGF-1 level was correlated to the time of therapy and dosage of GH. IGF-1-based GH dosing targeted to age- and gender-adjusted means may save medical costs and offer a more dose-sparing and potentially safer mode of therapy compared with traditional weight-based dosing.

A Prospective, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study Evaluating Meniscal Healing, Clinical Outcomes, and Safety in Patients Undergoing Meniscal Repair of Unstable, Complete Vertical Meniscal Tears (Bucket Handle) Augmented with Platelet-Rich Plasma

OBJECTIVE

The present study aimed to investigate the effectiveness and safety of platelet-rich plasma (PRP) application in arthroscopic repair of complete vertical tear of meniscus located in the red-white zone.

METHODS

This single center, prospective, randomized, double-blind, placebo-controlled, parallel-arm study included 37 patients with complete vertical meniscus tears. Patients received an intrarepair site injection of either PRP or sterile 0.9% saline during an index arthroscopy. The primary endpoint was the rate of meniscus healing in the two groups. The secondary endpoints were changes in the International Knee Documentation Committee (IKDC) score, Knee Injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and analog scale (VAS) in the two groups at 42 months.

RESULTS

After 18 weeks, the meniscus healing rate was significantly higher in the PRP-treated group than in the control group (85% versus 47%, P = 0.048). Functional outcomes were significantly better 42 months after treatment than at baseline in both groups. The IKDC score, WOMAC, and KOOS were significantly better in the PRP-treated group than in the control group. No adverse events were reported during the study period.

CONCLUSIONS

The findings of this study indicate that PRP augmentation in meniscus repair results in improvements in both meniscus healing and functional outcome.

Elevated C-Peptides, Abdominal Obesity, and Abnormal Adipokine Profile are Associated With Higher Gleason Scores in Prostate Cancer

BACKGROUND

Prostate cancer development is associated with numerous lifestyle factors (i.e., physical activity, nutrition intake) and metabolic perturbations. These factors have been studied independently; here, we used an integrative approach to characterize these lifestyle and metabolic parameters in men undergoing diagnostic prostate biopsies.

METHODS

We prospectively evaluated 51 consecutive men for body composition, metabolic factors including glucose- and lipid-related measures, as well as lifestyle factors prior to prostate biopsy. Evaluations were performed in a blinded manner and were subsequently related to biopsy outcomes for: (i) presence or absence of cancer; and (ii) where cancer was present, Gleason score.

RESULTS

Serum C-peptide concentrations were significantly greater in participants with Gleason scores ≥4 + 3 (2.8 ± 1.1 ng/ml) compared to those with Gleason 3 + 3 (1.4 ± 0.6 ng/ml) or Gleason 3 + 4 (1.3 ± 0.8 ng/ml, P = 0.002), suggesting greater insulin secretion despite lack of differences in fasting glucose concentrations. Central adiposity, measured by waist circumference, was significantly greater in participants with Gleason ≥4 + 3 (110.1 ± 7.4 cm) compared to those with Gleason 3 + 4 (102.0 ± 9.5 cm, P = 0.028). Men with Gleason ≥4 + 3 also had significantly greater leptin concentrations than those with lower Gleason scores (Gleason ≥4 + 3: 15.6 ± 3.3 ng/ml vs. Gleason 3 + 4: 8.1 ± 8.1 ng/ml, P < 0.05) and leptin:adiponectin ratio (Gleason ≥4 + 3: 9.7 ± 6.1 AU, Gleason 3 + 4: 2.9 ± 3.2, Gleason 3 + 3: 2.4 ± 2.1 AU, P = 0.013).

CONCLUSIONS

We profiled a cluster of obesity-related metabolic perturbations (C-peptide, central adiposity, leptin, and leptin:adiponectin ratios) which may associate with more aggressive prostate cancer histology. Prostate 77:211-221, 2017. © 2016 Wiley Periodicals, Inc.

Glucose metabolism during the acute prostate cancer treatment trajectory: The influence of age and obesity

BACKGROUND & AIMS

Obesity and age, key risk factors for aggressive prostate cancer, are associated with insulin resistance. Glucose-related parameters in patients with aggressive prostate cancer were compared with 2 reference groups: men of similar age and body mass index (BMI) without cancer, and healthy young men. Acute changes in these parameters following radiation treatment were also evaluated.

METHODS

Nine patients with aggressive prostate cancer underwent metabolic assessments prior to treatment (baseline), 7 and 33 weeks post-baseline (post-treatment initiation). Baseline measures were compared with the 2 reference groups. Evaluations included: 1) fasting and oral glucose tolerance test (OGTT) blood samples for glucose, C-peptide, and insulin, 2) fasting blood samples for triglycerides, cholesterols, leptin, adiponectin, IL-6, and TNF-α, 3) body composition, 4) nutrition, and 5) physical activity.

RESULTS

At baseline, patients had normal fasting glucose concentrations (<5.6 mM; 4.9 ± 1.2 mM) but impaired 2-h OGTT glucose concentrations (>7.8 mM; 8.7 ± 2.9 mM). Both reference groups had normal fasting (matched males: 4.2 ± 0.5 mM; young males: 3.7 ± 0.4 mM) and 2-h OGTT glucose concentrations (matched males: 5.6 ± 1.8 mM; young males: 3.1 ± 0.1 mM) that were significantly lower than patient values. During the OGTT, patients had higher insulin (120 min) and C-peptide (45, 60, 90, 120 min) concentrations compared to the matched males. At 7 weeks, 2-h OGTT glucose concentrations in patients improved to healthy ranges without changes in insulin, C-peptide, IGF-1, IGFBP-3 or other metabolic parameters.

CONCLUSIONS

At baseline patients with aggressive prostate cancer demonstrated impaired glucose tolerance compared with men of similar age and body size. Following treatment, glucose tolerance improved in the absence of changes in expected modifiers of glucose metabolism. These improvements may be related to treatment.

A New Homozygous IGF1R Variant Defines a Clinically Recognizable Incomplete Dominant form of SHORT Syndrome

Here, we describe a child, born from consanguineous parents, with clinical features of SHORT syndrome, high IGF1 levels, developmental delay, CNS defects, and marked progeroid appearance. By exome sequencing, we identified a new homozygous c.2201G>T missense mutation in the IGF1R gene. Proband's parents and other relatives, all heterozygous carriers of the mutation, presented with milder phenotype including high IGFI levels, short stature, and type 2 diabetes. Functional studies using patient's cell lines showed a lower IGF1R expression that leads to the alteration of IGF1R-mediated PI3K/AKT/mTOR downstream pathways, including autophagy. This study defines a clinically recognizable incomplete dominant form of SHORT syndrome, and provides relevant insights into the pathophysiological and phenotypical consequences of IGF1R mutations.

IGF-1: a potential biomarker for efficacy of sleep improvement with automatic airway pressure therapy for obstructive sleep apnea?

BACKGROUND

Positive airway pressure (PAP) reverses obstructive sleep apnea (OSA)-related hypoxia and restores slow wave sleep (SWS). Insulin-like growth factor 1 (IGF-1) is a neuropeptide that facilitates the repair of neurons from hypoxia and improves sleep regulation. IGF-1 concentrations are lower in OSA, and likely increase following PAP treatment; however, this relationship has not yet been determined in a younger cohort of OSA patients.

METHODS

This was a prospective, observational pilot study of 58 young men, who were diagnosed with OSA and provided PAP as an intervention. Adherence to PAP treatment over 3 months was objectively measured, as well as changes in the apnea-hypopnea index (AHI). Serum concentrations of IGF-1and C-reactive protein (CRP) were measured and correlated with PAP adherence.

RESULTS

IGF-1 concentrations at baseline were similar between PAP adherent 55.5 ± 34.4 ng/ml and PAP nonadherent participants 61.2 ± 27.1 ng/ml (p = 0.4), with the overall mean IGF-1 concentration of 59.0 ± 29.9 ng/ml. At follow-up, adherent participants had concentrations of IGF-1 that were significantly higher 128 ± 59.5 ng/ml compared to nonadherent participants 86.0 ± 47.4 ng/ml (p < 0.01). Increases in IGF-1 concentrations were significantly associated with reductions in AHI (Spearman's rho = -0.409, p = 0.015). Conversely, CRP concentrations did not differ between baseline and follow-up measurements in either group.

CONCLUSIONS

Adherence to PAP treatment leads to significant increases in IGF-1 concentrations in young men with OSA. While an objective measure of adherence exists, PAP usage does not allow for measure of sleep improvement. IGF-1 may serve as a potential biomarker for the efficacy of PAP therapy on improved sleep.

Association between the insulin-like growth factor axis in serum and periodontitis in the Study of Health in Pomerania: an exploratory study

AIM

To evaluate the association of Insulin-like Growth Factor (IGF) I-related variables with periodontitis in the population-based Study of Health in Pomerania (SHIP).

MATERIAL AND METHODS

From the cross-sectional SHIP, 2293 subjects with clinical attachment loss (CAL) data and 2398 subjects with tooth count data aged 20-59 years were analysed. Serum IGF-I and IGF-binding protein (BP)-3 levels were determined by chemiluminescence immunoassays. Linear and logistic regressions with fractional polynomials were used to study associations between IGF-related variables and mean CAL or high tooth loss. For non-linear relations between IGFBP-3 and mean CAL, graphical presentations of fractional polynomials were used to deduce knots for linear splines.

RESULTS

In fully adjusted models, for serum IGFBP-3 values ≤1200 ng/ml, mean CAL increased significantly for decreasing serum IGFBP-3 levels [B = -0.027 (95% CI, -0.049; -0.005), p = 0.02]. The odds for high tooth loss decreased significantly for high serum IGFBP-3 values [OR = 0.97 (0.95; 0.99), p = 0.02]. Serum IGF-I levels and the IGF-I/IGFBP-3 ratio were not related to mean CAL or tooth loss after full adjustment.

CONCLUSIONS

Low serum IGFBP-3 levels might be associated with higher levels of periodontal disease. Neither serum IGF-I nor IGF-I/IGFBP-3 ratios were associated with periodontitis.

Traumatic brain injury causes long-term reduction in serum growth hormone and persistent astrocytosis in the cortico-hypothalamo-pituitary axis of adult male rats

In humans, traumatic brain injury (TBI) causes pathological changes in the hypothalamus (HT) and the pituitary. One consequence of TBI is hypopituitarism, with deficiency of single or multiple hormones of the anterior pituitary (AP), including growth hormone (GH). At present no animal model of TBI with ensuing hypopituitarism has been demonstrated. The main objective of this study was to investigate whether cortical contusion injury (CCI) could induce long-term reduction of serum GH in rats. We also tested the hypothesis that TBI to the medial frontal cortex (MFC) would induce inflammatory changes in the HT and AP.

METHODS

Nine young adult male rats were given sham surgery (n = 4) or controlled impact contusions (n = 5) of the MFC. Two months post-injury they were killed, trunk blood collected and their brains and AP harvested. GH was measured in serum and AP using ELISA and Western blot respectively. Interleukin-1beta (IL-1beta) and glial fibrillary acidic protein (GFAP) were measured in the cortex (Cx), HT, and AP by Western blot.

RESULTS

Lesion rats had significantly (p < 0.05) lower levels of GH in the AP and serum, unaltered serum IGF-1, and significantly (p < 0.05) higher levels of IL-1beta in the Cx and HT and GFAP in the Cx, HT, and AP compared to that of shams.

CONCLUSION

CCI leads to a long-term depletion of serum GH in male rats. This chronic change in GH post-TBI is probably the result of systemic and persistent inflammatory changes observed at the level of HT and AP, the mechanism of which is not yet known.

Traumatic brain injury causes long-term reduction in serum growth hormone and persistent astrocytosis in the cortico-hypothalamo-pituitary axis of adult male rats

In humans, traumatic brain injury (TBI) causes pathological changes in the hypothalamus (HT) and the pituitary. One consequence of TBI is hypopituitarism, with deficiency of single or multiple hormones of the anterior pituitary (AP), including growth hormone (GH). At present no animal model of TBI with ensuing hypopituitarism has been demonstrated. The main objective of this study was to investigate whether cortical contusion injury (CCI) could induce long-term reduction of serum GH in rats. We also tested the hypothesis that TBI to the medial frontal cortex (MFC) would induce inflammatory changes in the HT and AP.

METHODS

Nine young adult male rats were given sham surgery (n = 4) or controlled impact contusions (n = 5) of the MFC. Two months post-injury they were killed, trunk blood collected and their brains and AP harvested. GH was measured in serum and AP using ELISA and Western blot respectively. Interleukin-1beta (IL-1beta) and glial fibrillary acidic protein (GFAP) were measured in the cortex (Cx), HT, and AP by Western blot.

RESULTS

Lesion rats had significantly (p < 0.05) lower levels of GH in the AP and serum, unaltered serum IGF-1, and significantly (p < 0.05) higher levels of IL-1beta in the Cx and HT and GFAP in the Cx, HT, and AP compared to that of shams.

CONCLUSION

CCI leads to a long-term depletion of serum GH in male rats. This chronic change in GH post-TBI is probably the result of systemic and persistent inflammatory changes observed at the level of HT and AP, the mechanism of which is not yet known.

Retesting the childhood-onset GH-deficient patient

GH deficiency (GHD) in adults has to be shown by a single provocative test, provided that it is validated. Insulin tolerance test (ITT) has been indicated as the test of choice; now also glucagon test is validated and represents an alternative. The GHRH plus arginine (ARG) test and testing with GHRH plus a GH secretagogue are equally reliable diagnostic tools, and are now considered as 'golden' standards as ITT. Childhood-onset (CO) GHD needs retesting in late adolescence or young adulthood; this is a major clinical challenge and raises questions about the most appropriate method and cut-off value. Appropriate re-evaluation of GH status is represented by simple measurement of IGF1 concentration off rhGH treatment. Clearly, low IGF1 levels are evidence of persistent severe GHD in subjects with genetic GHD or panhypopituitarism. However, normal IGF1 levels never rule out severe GHD and CO-GHD with normal IGF1 levels must undergo a provocative test. The appropriate GH cut-off limit is specific for each provocative test. As shown by the ROC curve analysis, in late adolescents and young adults, the lowest normal GH peak response to ITT is 6.1 microg/l while that to GHRH+ARG test is 19.0 microg/l. These cut-off limits, however, are just indicative as being variable as a function of the assay used. No other test is validated for retesting. As GHRH+ARG test mostly explores the GH-releasable pool, normal GH response would be verified by a second ITT in order to rule out subtle hypothalamic defect.

Serum IGF-I measured by four different immunoassays in patients with adult GH deficiency or acromegaly and in a control population

BACKGROUND

IGF-I is a useful tool in GH disorders diagnosis, however, the use of commercially available kits needs to be validated.

OBJECTIVE

To validate the use of serum IGF-I concentrations measured by four immunoassays in the diagnosis of adult GH deficiency and acromegaly.

DESIGN

Cross-sectional study.

PATIENTS

Fifty GH-deficient (GHD) patients, 41 acromegaly patients and 405 controls.

MEASUREMENTS

Serum IGF-I concentrations were measured by four commercial immunoassays: (1) RIA-NICHOLS; (2) ICMA-IMMULITE; (3) IRMA-IMMUNOTECH; and (4) non-extraction-IRMA-DSL. Reference values were established from the control population in six age groups. Individual results were transformed to standard deviation score (SD score) from the age-related reference population and reference data provided by each assay manufacturer. Diagnostic sensitivity for GH deficiency was calculated.

RESULTS

IGF-I measured by the four assays differed significantly. In controls, assay 2 yielded the lowest results, followed by assays 1, 3 and 4 (P < 0.0001 for all comparisons). IGF-I declined with age, but no sex-related differences were observed. When IGF-I was standardized with respect to reference data obtained from the manufacturers, it showed better sensitivity in assays 1 and 2, than with our controls (65%vs. 77.5% and 58%vs. 70%, respectively) for GHD diagnosis. With assays 3 and 4, higher sensitivity was obtained when standardized with our controls (62%vs. 52% and 56%vs. 36%, respectively). In acromegaly, IGF-I was > 2 SD score with all assays.

CONCLUSIONS

IGF-I SD score for GHD diagnosis differed according to the normative data used. All assays proved to be useful for active acromegaly diagnosis.

Normal age-dependent values of serum insulin growth factor-I: results from a healthy Italian population

Serum IGF-I levels were measured in 547 non-hypopituitaric, non-acromegalic healthy subjects of both sexes in Italy to develop reference values in relation to age and sex. Participant subjects were stratified in three age classes (25- 39, 40-59 and >or=60 yr) and IGF-I assay was carried out by double-antibody radio immunoassay. Pearson's correlation coefficient between age and IGF-I values was calculated by sex and predefined age ranges. IGF-I levels significantly decreased with age (p<0.001, Kruskal-Wallis test) while sex was not a significant factor. The median IGF-I levels were 206 ng/ml in the 25-39 yr range, 147 ng/ml in the 40-59 yr range and 103 ng/ml in the >or=60 yr range. Pearson's correlation coefficient confirmed the negative correlation between age and IGF-I levels in the total sample of subjects (r=-0.529). The r coefficient between age and IGF-I levels did not differ between sexes (r=-0.570 in males and r=-0.529 in females), thus reflecting no sex-effect on IGF-I levels decline over years. No correlations were found in the 25-39 yr range (r=-0.036) or in the 40-59 yr range (r=-0.080) either, while in subjects aged >60 yr, IGF-I levels tended to further decrease with increased age (r=0.389). Ranges of normal values set at the 2.5th-97.5th percentile in the three age ranges were 95.6-366.7 ng/ml between 25 and 39 yr, 60.8-297.7 ng/ml between 40 and 59 yr and 34.5-219.8 ng/ml in subjects aged >or=60 yr. This study may contribute to the development of age-specific reference ranges for IGF-I determination in serum of normal subjects of both sexes in Italy.

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.

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.

Diagnostic strategy for growth hormone deficiency: relevance of IGF-1 determination as a screening test

BACKGROUND

Adult growth hormone (GH) deficiency must be diagnosed before prescribing therapeutic recombinant human GH. We studied the clinical relevance of a diagnostic strategy for growth hormone deficiency (GHD) using IGF-1 determination as a first step.

METHODS

In 2000 and 2001, we tested 142 adult patients with hypothalamo-pituitary disorders for somatotropic function using Insulin Tolerance Test (ITT), the reference test for the diagnosis of GHD, with concomitant Insulin-like growth factor-1 (IGF-1) determination, a marker of somatotropic function. Patients were classified as GHD (peak GH concentration<3 ng/ml with the ITT) or normal.

SETTING

Monocenter prospective study in a tertiary referral center.

RESULTS

GHD was diagnosed in 61 subjects. Using a ROC curve, a threshold IGF-1 concentration of 175 ng/ml yielded a negative predictive value of 89+/-5%. A diagnostic strategy with IGF-1 determination as the first step followed by ITT for patients with an IGF-1 concentration below 175 ng/ml missed five of the 61 GHD patients, avoided 46/142 ITT and reduced the cost of diagnosis by 15%.

CONCLUSION

We propose the use of a strategy consisting of IGF-1 determination followed, if below 175 ng/ml by confirmatory ITT to diagnose GHD in adults.

Serum concentrations of insulin-like growth factor-I (igf-I) as a marker of liver fibrosis in patients with chronic hepatitis C

Liver biopsy was until recently the only way of evaluating liver fibrosis. Noninvasive tests for hepatic fibrosis, without potential risks, are desired by clinicians as well as patients. Insulin-like growth factor-I (IGF-I) synthesis is disturbed in liver fibrosis and reflects the severity of the clinical stage. We assessed serum IGF-I levels in patients with chronic hepatitis C (CHC) to correlate with liver fibrosis and antiviral therapy. Forty patients with CHC and persistently abnormal alanine aminotransferase values were enrolled and treated with peginterferon alpha-2a 180 microg per week plus ribavirin for 24 (n=20) or 48 (n=20) weeks. All patients underwent liver biopsy before treatment (METAVIR fibrosis stage F0, n=13; F1-F2, n=14; F3, n=7; F4, n=6). Serum IGF-I was measured at baseline, at the end of treatment period, and 24 weeks after finishing treatment. Mean IGF-I values were significantly lower in patients with advanced fibrosis (F4, 65.9+/-17.9 ng/mL) than in the others (F0, 145.2+/-47.1; F1-F2, 150.3+/-89.6; and F3, 121.4+/-35.2 ng/mL; P < .05). Serum IGF-I levels increased during combined therapy, being this increment markedly higher in patients with sustained virologic response. In conclusion, IGF-I synthesis is disturbed in CHC and reflects the severity of the liver fibrosis. Combined therapy improves serum IGF-I levels. IGF-I could represent a good, noninvasive marker of liver fibrosis.

Growth Hormone Perturbations in Fibromyalgia: A Review

OBJECTIVE

Fibromyalgia (FM) is a syndrome characterized by chronic widespread pain, fatigue, disrupted sleep, depression, and physical deconditioning. In this article, we review the literature on the normal activity of the hypothalamic-pituitary-growth hormone-insulin-like growth factor-1 (HP-GH-IGF-1) axis and its perturbations in FM subjects.

METHODS

Studies included in this review were accessed through an English language search of Cochrane Collaboration Reviews. Keyword MeSH terms included "fibromyalgia," "growth hormone" (GH), or "insulin-like growth factor-1" (IGF-1).

RESULTS

Twenty-six studies enrolling 2006 subjects were reviewed. Overall, low levels of IGF-1 were found in a subgroup of subjects. Growth hormone stimulation tests often revealed a suboptimal response, which did not always correlate with IGF-1 levels. No consistent defects in pituitary function were found. Of the 3 randomized placebo controlled studies, only 9 months of daily injectable recombinant GH reduced FM symptoms and normalized IGF-1.

CONCLUSIONS

These studies suggest that pituitary function is normal in FM and that reported changes in the HP-GH-IGF-1 axis are most likely hypothalamic in origin. The therapeutic efficacy of supplemental GH therapy in FM requires further study before any solid recommendations can be made.

Defining Growth Hormone Status in Adults with Hypopituitarism

The identification of adults with severe growth hormone (GH) deficiency (GHD) is not straightforward. The insulin tolerance test remains the gold standard diagnostic test, although other stimuli such as GH-releasing hormone-arginine are gaining acceptance. Insulin-like growth factor-I has a poor diagnostic sensitivity in adult-onset GHD, but is more useful in the subgroup of adults with childhood-onset GHD. Therapeutic developments include increasing recognition of the need to continue GH therapy beyond final height in young adults with severe GHD on retesting. Consensus guidelines have provided a useful algorithm to identify individuals requiring retesting and the number of tests needed. The concept of partial GHD, recognized by paediatric endocrinologists for many years, is being examined in adults with hypothalamic-pituitary disease. Preliminary evidence suggests that this entity is associated with metabolic and anthropometric abnormalities intermediate between those in severe GHD and in healthy controls. It remains to be seen whether this subgroup will derive benefit from GH therapy. To date, therapeutic benefits of GH have been demonstrated only in adults with severe GHD. It is, therefore, imperative that these individuals are unequivocally identified; the diagnosis becomes more uncertain in the presence of obesity, increasing age, and in the absence of additional pituitary hormone deficits.

Value of insulin-like growth factor system markers in the assessment of growth hormone status

Insulin-like growth factor-I (IGF-I) has been measured extensively in a variety of clinical settings. Total IGF-I frequently is used to assess the clinical impact of disorders of GH secretion and to monitor patients' response to therapy. It does not have sufficient precision to be used as a stand-alone test in the diagnosis of GH deficiency. Free IGF-I, IGF binding protein-3, or acid-labile subunit may provide useful information regarding GH secretion in specific conditions but are not superior to IGF-I for making the diagnosis of GH deficiency or acromegaly.

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.

IGF-I measurements in the diagnosis of adult growth hormone deficiency

Although serum insulin-like growth factor I (IGF-I) concentrations have utility as a screening test for growth hormone (GH) deficiency in children and young adults, they are less accurate for screening in adults over 40 years of age. There are two main limitations in the clinical use of IGF-I levels as a marker of GH secretion. First, IGF-I synthesis is not only regulated by GH but also by nutrient supply and by other hormones; second, low IGF-I levels in the presence of normal or increased GH secretion may reflect a peripheral resistance to GH action. Although serum IGF-I cannot be used as a stand-alone test for the diagnosis of adult GH deficiency, very low IGF-I levels in the context of documented hypothalamic or pituitary disease may be helpful in identifying patients with a high probability of GH deficiency. In the presence of two or more additional pituitary hormone deficiencies, an IGF-I level <84 microg/l (assayed by Esoterix Endocrinology, Inc. Calabasas Hills, CA, USA) indicates a 99% probability of GH deficiency. As this cut-off value has not been validated for other IGF-I assays, an IGF-I standard deviation score (SDS) of <-3 may be considered in adults over age 28; an even lower IGF-I SDS is needed for diagnosis in younger adults. In clinical practice, other causes of low serum IGF-I such as malnutrition, diabetes, hypothyroidism, liver disease, etc., should be excluded before applying these diagnostic criteria.

Approach to the evaluation of the GH/IGF-axis in patients with pituitary disease: which test to order

The diagnosis of adult growth hormone deficiency (AGHD) and acromegaly involves assessment of serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) concentrations. The diagnosis of AGHD typically requires a provocative test of GH reserve, but is supported by demonstration of low-serum IGF-1 levels. Therapeutic monitoring of rhGH replacement is performed utilizing measurement of serum IGF-1 concentrations. In patients with suspected acromegaly, the diagnosis is confirmed by elevated serum IGF-1 levels and further validated by the presence of elevated GH levels both before and following an oral glucose load. A goal of acromegaly therapy is to normalize IGF-1 concentrations, and, depending on the therapeutic modality, GH levels as well. Using case based clinical scenarios, we have presented a standard approach to the biochemical diagnosis and therapeutic monitoring of these disorders.

Assessment of serum IGF-I concentrations in the diagnosis of isolated childhood-onset GH deficiency: a proposal of the Italian Society for Pediatric Endocrinology and Diabetes (SIEDP/ISPED)

The diagnosis of GH deficiency (GHD) is based on the measurement of peak GH responses to pharmacological stimuli. Pharmacological stimuli, however, lack precision, accuracy, are not reproducible, are invasive, non-physiological and some may even be hazardous. Furthermore, different GH commercial assays used to measure GH in serum yield results that may differ considerably. In contrast to GH, IGF-I can be measured on a single, randomly-obtained blood sample. A review of the available data indicates that IGF-I measurement in the diagnosis of childhood-onset isolated GHD has a specificity of up to 100%, with a sensitivity ranging from about 70 to 90%. We suggest an algorithm in which circulating levels of IGF-I together with the evaluation of auxological data, such as growth rate and growth, may be used to assess the likelihood of GHD in pre-pubertal children.

Insulin-Like Growth Factor I Levels and the Diagnosis of Adult Growth Hormone Deficiency

The current guidelines state that, within the appropriate clinical context, the diagnosis of adult growth hormone (GH) deficiency must be made biochemically using provocative tests. Measurement of insulin-like growth factor I (IGF-I) and binding protein 3 (IGFBP-3) levels cannot always distinguish between healthy and GH-deficient individuals. In particular, IGFBP-3 as a marker of GH status is clearly less sensitive than IGF-I and there is general agreement that its measurement does not provide useful diagnostic information. However, the diagnostic value of measuring IGF-I levels has been revisited recently. It has been confirmed that normal IGF-I levels do not rule out severe GH deficiency (GHD) in adults, in whom the diagnosis has therefore to be based on the demonstration of severe impairment of the peak GH response to provocative tests. It has also been emphasized that very low IGF-I levels in patients with high suspicion of GHD could be considered to be definite evidence for severe GHD. This assumption particularly applies to patients with childhood-onset, severe GHD or with multiple hypopituitary deficiencies acquired in adulthood. In addition, the use of IGF-I levels to monitor the efficacy and adequacy of recombinant human GH replacement remains widely accepted.

Insulin-Like Growth Factor I Levels in Healthy Adults

Insulin-like growth factor I (IGF-I) levels mainly reflect secretion of growth hormone (GH) in the body. The aims of this study were to compare different IGF-I assay methods in healthy individuals, test the reliability of the methods and discuss the utility of IGF-I measurement in adults. The Nichols Institute Diagnostics radioimmunoassay was used to evaluate IGF-I in two random population samples of men and women (aged 25-64 years, n = 392) taken 10 years apart, in 1985 and 1995. This method for IGF-I testing was also compared with an immunoradiometric assay (IRMA) method in 387 men and women participating in the World Health Organization MONICA (MONItoring of trends and determinants for CArdiovascular diseases) Project, Goteborg, Sweden, in 1995. Serum IGF-I decreased with increasing age in both men and women. IGF-I was higher in young women compared with young men in both cohorts, while the opposite was found in the highest age group. Age-adjusted significant correlations were found between IGF-I and smoking, fibrinogen, coffee consumption, lipoprotein (a), osteocalcin and IGF-binding protein 3. The two cohorts showed similar mean IGF-I concentrations irrespective of method. The correlation between the Nichols and the IRMA methods was high: r = 0.93 (p < 0.0001). Based on this and previous studies, population-based IGF-I measurements are robust irrespective of which commercially available method of assay is used. IGF-I levels can be used in diagnosing acromegaly as well as providing target values. IGF-I assay can be used as a complement to stimulation testing in the diagnosis of GH deficiency, and as a tool for GH dose titration.

Diagnostic reliability of a single IGF-I measurement in 237 adults with total anterior hypopituitarism and severe GH deficiency

OBJECTIVE

Within an appropriate clinical context, GH deficiency (GHD) in adults must be demonstrated biochemically by a single provocative test. Insulin-induced hypoglycaemia (ITT) and GH-releasing hormone (GHRH) + arginine (ARG) are indicated as the tests of choice, provided that appropriate cut-off limits are defined. Although IGF-I is the best marker of GH secretory status, its measurement is not considered a reliable diagnostic tool. In fact, considerable overlap between GHD and normal subjects is present, at least when patients with suspected GHD are considered independently of the existence of other anterior pituitary defects. Considering the time and cost associated with provocative testing procedures, we aimed to re-evaluate the diagnostic power of IGF-I measurement.

DESIGN

To this goal, in a large population [n = 237, 139 men, 98 women, age range 20-80 years, body mass index (BMI) range 26.4 +/- 4.3 kg/m2] of well-nourished adults with total anterior pituitary deficit including severe GHD (as shown by a GH peak below the 1st centile limit of normal response to GHRH + ARG tests and/or ITT) we evaluated the diagnostic value of a single total IGF-I measurement. IGF-I levels in hypopituitary patients were evaluated based on age-related normative values in a large population of normal subjects (423 ns, 144 men and 279 women, age range 20-80 years, BMI range 18.2-24.9 kg/m2).

RESULTS

Mean IGF-I levels in GHD were lower than those in normal subjects in each decade, but not the oldest one (74.4 +/- 48.9 vs. 243.9 +/- 86.7 micro g/l for 20-30 years; 81.8 +/- 46.5 vs. 217.2 +/- 56.9 micro g/l for 31-40 years; 85.8 +/- 42.1 vs. 168.5 +/- 69.9 micro g/l for 41-50 years; 82.3 +/- 39.3 vs. 164.3 +/- 60.3 micro g/l for 51-60 years; 67.5 +/- 31.8 vs. 123.9 +/- 50.0 micro g/l for 61-70 years; P < 0.0001; 54.3 +/- 33.6 vs. 91.6 +/- 53.5 micro g/l for 71-80 years, P = ns). Individual IGF-I levels in GHD were below the age-related 3rd and 25th centile limits in 70.6% and 97.63% of patients below 40 years and in 34.9% and 77.8% of the remaining patients up to the 8th decade, respectively.

CONCLUSIONS

Total IGF-I levels are often normal even in patients with total anterior hypopituitarism but this does not rule out severe GHD that therefore ought to be verified by provocative testing of GH secretion. However, despite the low diagnostic sensitivity of this parameter, very low levels of total IGF-I can be considered definitive evidence of severe GHD in a remarkable percentage of total anterior hypopituitary patients who could therefore skip provocative testing of GH secretion.

Use of the oral glucose tolerance test to define remission in acromegaly

An oral glucose tolerance test (OGTT) was used to assess growth hormone (GH) secretion in patients with acromegaly prior to (n = 26) and after (n = 71) transsphenoidal adenomectomy as well as in 196 controls. In controls, suppressed concentrations of GH showed a negative relationship both with body mass index (BMI) and with age. Having calculated the reference intervals for suppressed GH concentrations to be expected for any given age and BMI, we compared these individually predicted ranges to GH concentrations actually observed in patients with acromegaly during OGTT. Preoperatively, concentrations exceeded the normal range in all patients. Postoperatively, glucose-suppressed concentrations of GH were less than 2.0 ng/mL in 56 (79%) patients and less than 1.0 ng/mL in 44 (62%). However, only 37 of 71 (52%) patients had glucose-suppressed GH concentrations within the calculated reference intervals (defined by the 95th percentile of normal). Comparing these data with the patient's concentrations of insulin-like growth factor-1 (IGF-1; normal range first established and corrected for age and sex in 494 healthy individuals), congruency of both parameters was found in 59 (77%) patients with an unexplained discrepancy between GH and IGF-1 in the remaining in 16 (23%) patients. Our results confirm that concentrations of IGF-1 must be corrected for sex and age, whereas glucose-suppressed concentrations of GH depend on age and BMI. "Across-the-board" cut-off-values are clearly inadequate and should not be used. Rather, serum GH measurements obtained during an OGTT must be interpreted individually by comparison to control values taking into account both age and BMI.

Height velocity and IGF-I assessment in the diagnosis of childhood onset GH insufficiency: do we still need a second GH stimulation test?

OBJECTIVE

The diagnosis of GH insufficiency (GHI) in childhood is not straightforward. Our aim was to test the sensitivity and specificity of height velocity (HV), IGF-I, IGFBP-3 and GH stimulation tests alone or in combination in the diagnosis of GHI.

DESIGN

A retrospective review of patients with GHI and idiopathic short stature (ISS) diagnosed in our centre and followed up to the completion of linear growth.

PATIENTS

Thirty-three GHI children and 56 children with ISS were evaluated. GHI diagnosis was based on fulfilment of anthropometric, endocrine and neuroradiological criteria: stature < or = -2 z-score, delayed bone age (at least 1 year), GH peak response to at least two different provocative tests < 10 micro g/l (20 mU/l), brain MRI positive for hypothalamus-pituitary abnormalities, catch-up growth during the first year of GH replacement therapy > or = 75th centile, peak GH response to a third provocative test after growth completion < 10 micro g/l (20 mU/l). Children with anthropometry resembling that of GHI but with peak GH responses > 10 micro g/l (20 mU/l) were diagnosed as ISS.

MEASUREMENTS

All subjects underwent standard anthropometry. GH secretory status was assessed by clonidine, arginine and GHRH plus arginine stimulation tests. IGF-I and IGFBP-3 circulating levels were measured by immunoradiometric assay (IRMA). The following cut-off values were chosen to discriminate between GHI and nonGHI short children: HV < 25th centile over the 6-12 months prior to the initiation of GH therapy, peak GH responses < 10 or < 7 micro g/l (< 20 or < 14 mU/l) and IGF-I and IGFBP-3-values < -1.9 z-score. Sensitivity (true positive ratio) and specificity (true negative ratio) were evaluated.

RESULTS

Taking 10 micro g/l (20 mU/l) as the cut-off value, sensitivity was 100% and specificity 57% for GH provocative tests, whereas taking 7 as the cut-off value, sensitivity was 66% and specificity rose to 78%. Sensitivity was 73% for IGF-I and 30% for IGFBP-3 measurement, whilst specificity was 95% for IGF-I and 98% for IGFBP-3 evaluation. HV assessment revealed a sensitivity of 82% and a specificity of 43%. When HV and IGF-I evaluations were used in combination, sensitivity reached 95% and specificity 96%. When both HV and IGF-I are normal (26% of our subjects) GHI may be ruled out, whereas when both the indices are subnormal (23%) GHI is so highly likely that the child may undergo only one GH provocative test and brain MRI and, thereafter, may begin GH therapy without any further test. In case of discrepancy, when IGF-I is normal and HV < 25th centile (44% of children), due to the relatively low sensitivity of IGF-I assessment and low specificity of HV, the patient should undergo GH tests and brain MRI. Finally, in the rare case of HV > 25th centile and subnormal IGF-I-values (7%), due to the high specificity of IGF-I measurement, the child should undergo one provocative test and brain MRI for the high suspicion of GHI.

CONCLUSIONS

Our results suggest that a simple assessment of HV and basal IGF-I may exclude or, in association with only one stimulation test, confirm the diagnosis of GH insufficiency in more than half of patients with short stature.

Urinary insulin-like growth factor I in athletes, before and after physical exercise, and in sedentary subjects

BACKGROUND

Insulin-like growth factor I (IGF-I), like growth hormone (GH), is excreted in urine in a smaller fraction than the concentration found in blood. Exercising subjects undergo post-exercise proteinuria. The present work aims to propose a method for urinary IGF-I analysis (uIGF-I) by defining urinary concentration in sedentary individuals and athletes before and after strenuous exercise.

METHODS

Urine samples were collected from 30 sedentary healthy male individuals during the morning and from 30 well-trained cyclists, before and after a competition of about 3 h (150 km). uIGF-I was measured in undiluted acidified urine by radioimmunoassay (RIA) method using a purified polyclonal rabbit antibody, human 125I-IGF-I and a second anti-rabbit antiserum. The acidification of the urine samples and the excess of IGF-II addition in the incubation medium of the assay were used to dissociate the binding and to block the interference from IGF binding proteins (IGFBPs). Urinary growth hormone (uGH), total protein (utPr) and creatinine (ucr) concentrations were also measured by immunoradiometric assay (IRMA), colorimetric and capillary electrophoresis methods, respectively.

RESULTS

The analysis range was 0-2500 ng/l (0-327 pmol/l), the intra- and inter-assay coefficients of variations (CVs) ranged from 2.3% to 7.8%, respectively. The detection limit was 0.6 pg/tube. The uIGF-I/creatinine (cr) ratio in healthy subjects was 70 +/- 8 pg/mg cr. The uIGF-I/creatinine ratio (pg/mg cr) was different (p<0.001) in athletes before vs. after competition 93 +/- 27 vs. 136 +/- 13. Athletes' [uIGF-I/total proteins] ratio (ng/mg tPr) before and post-exercise was 2.3 +/- 0.5 and 2.5 +/- 0.3, respectively.

CONCLUSIONS

uIGF-I assay appears to be an effective way of monitoring IGF-I excretion. In the cyclists, in the pre-exercise state, uIGF-I was comparable with that measured in sedentary healthy individuals. In the cyclists, after strenuous exercise, the increased uIGF-I/cr and uGH/cr ratios suggested a relation with the post-exercise proteinuria. In conclusion, proteinuria physiologically obtained, such as post-exercise proteinuria, might be a new approach in IGF-I system investigation.

Late onset of adrenocortical failure in GH deficiency with invisible pituitary stalk: a case report of a 48-year-old Japanese man and review of the literature

ACTH deficiency gradually develops in patients with growth hormone deficiency (GHD) who have abnormalities of the pituitary stalk on magnetic resonance imaging (MRI) following perinatal complications. We report here a rare case of GHD manifesting ACTH deficiency in middle age. A 48-year-old male patient was admitted to our hospital due to fever and hyponatremia. He was diagnosed as GHD and hypothyroidism at the age of 9, and had received lysine treatment until age 20, which was then replaced by thyroid hormone. He was not mentally retarded, but was the shortest in his class throughout his schooldays, reaching a final height of 148 cm. Hormonal examination revealed the presence of hypoadrenalism as indicated by poor responses of plasma cortisol to intravenous administration of corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia. Plasma ACTH responded well to CRH, but not to insulin-induced hypoglycemia, indicating that his hypoadrenalism was of hypothalamic origin. MRI showed an invisible pituitary stalk and relatively small pituitary gland. Since he had a perinatal abnormality, the damage around the pituitary and GHD could have originated from birth. In the literature, around 60% of GHD patients with pituitary stalk abnormalities develop hypoadrenalism due to ACTH deficiency, and more than 90% of such cases are diagnosed by age 30. We suggest that the appearance of hypoadrenalism should be carefully monitored in GHD patients with pituitary stalk abnormalities even after they reach middle age.

Growth hormone release after glucagon as a reliable test of growth hormone assessment in adults

OBJECTIVE

To investigate the GH response to glucagon in adult patients with GH deficiency and in controls compared with the GH response to the insulin tolerance test (ITT) in patients with GH deficiency and to determine whether the use of glucagon results in a diagnostic utility test.

PATIENTS AND DESIGN

Seventy-three patients with adult GH deficiency and organic hypothalamic-pituitary disease were recruited, along with 46 controls. The patients were divided into five groups according to the number of associated hormone deficiencies present.

MEASUREMENTS

Hypopituitary subjects underwent assessment of GH secretory status by the ITT, the glucagon test and measurement of serum IGF-I concentration. Controls underwent the glucagon test. After the ITT, glucose and GH levels were measured at baseline, 30, 60 and 90 minutes, and after glucagon at baseline, 90, 120, 150, 180, 210 and 240 minutes.

RESULTS

The highest GH value after the ITT in the patient group was 3 microg/l (0.76 +/- 0.82 microg/l), and after the glucagon test the highest GH peak value was 2.9 microg/l (0.64 +/- 0.79 microg/l). A correlation was found between the GH peak and the progressive number of hormone deficiencies. After the glucagon test, the GH peak obtained in the controls at 180 minutes was 9.8 +/- 4.6 microg/l and, on an individual basis, none of the 46 controls failed to achieve peak GH levels higher than 3 microg/l. In the controls, a negative correlation was observed between the GH response to glucagon and age (r = -0.389, P = 0.0075) and body mass index (r = -0.329, P = 0.0254). The accuracy of the glucagon test for differentiating patients from controls, estimated by receiver operating characteristics (ROC) curve methodology, showed that the cut-off of 3 microg/l for the GH peak provides 100% sensitivity and 100% specificity and is a reliable decision threshold.

CONCLUSIONS

The glucagon GH test is reliable and provides a clear separation between GH-deficient and normal adults. A single glucagon test with a cut-off of 3 microg/l for the GH peak is diagnostic of GH deficiency in adults and could be considered and studied as an alternative to the ITT.