Sensitivity and specificity of six tests for the diagnosis of adult GH deficiency

Diagnosing growth hormone deficiency in adults

Adult growth hormone (GH) deficiency is a recognised syndrome associated with adverse phenotypic, metabolic, and quality-of-life features which improve in many patients when GH is substituted. The appropriate selection of patients at risk of growth hormone deficiency (GHD) is the crucial first step in arriving at a correct diagnosis. Although multiple diagnostic modalities are available including a 24-hour serum GH profile, stimulated GH levels, and insulin-like growth factor-1 (IGF-1) levels, the use of dynamic tests for GH reserves is required in most cases. This paper discusses the utility and drawbacks of the various testing modalities with reference to international guidelines. Regardless of the test chosen, clinical pitfalls including age and obesity must be taken into account. In addition, there is considerable analytical variation in the biochemical measurements of GH and IGF-1 which must be considered before making a diagnosis of GHD in adulthood.

Pituitary dysfunction after traumatic brain injury: screening and hormone replacement

This article highlights the risk of hypopituitarism in survivors of traumatic brain injury (TBI), an underdiagnosed clinical problem. Clinical evidence shows that anterior pituitary dysfunction is common in TBI survivors evaluated at least 6 months after the TBI, with an estimated prevalence of up to 27.5%. Although patients who suffer from moderate-to-severe TBI appear to be at higher risk, the emerging data suggest that mild-intensity trauma can also precede hypopituitarism. Since many of the symptoms of hypopituitarism are similar to those of TBI, it is important for clinicians to be aware of this clinical problem. Moreover, we will address questions such as when to screen and who should be screened, along with a discussion of current management of pituitary dysfunction in patients with TBI.

Adult growth hormone deficiency

Adult growth hormone deficiency (AGHD) is being recognized increasingly and has been thought to be associated with premature mortality. Pituitary tumors are the commonest cause for AGHD. Growth hormone deficiency (GHD) has been associated with neuropsychiatric-cognitive, cardiovascular, neuromuscular, metabolic, and skeletal abnormalities. Most of these can be reversed with growth hormone therapy. The insulin tolerance test still remains the gold standard dynamic test to diagnose AGHD. Growth hormone is administered subcutaneously once a day, titrated to clinical symptoms, signs and IGF-1 (insulin like growth factor-1). It is generally well tolerated at the low-doses used in adults. Pegylated human growth hormone therapy is on the horizon, with a convenient once a week dosing.

Glucagon stimulation testing in assessing for adult growth hormone deficiency: current status and future perspectives

Growth hormone deficiency (GHD) is a well-recognized clinical syndrome in adults. However, due to the high frequency of normal serum IGF-I levels in hypopituitary adults with GHD, it is now widely accepted that despite normal levels of total IGF-I, adults clinically suspected with GHD within the appropriate clinical setting must undergo GH provocative testing to confirm its diagnosis. Although the insulin tolerance test (ITT) is labor intensive, contraindicated in the elderly and in adults with seizure disorders and ischemic heart disease, can be unpleasant for the patient, and is potentially hazardous, this test remains the gold standard test for the biochemical demonstration of GHD in adults. In contrast, with the unavailability of the GHRH and arginine test as the alternative test to the ITT in the United States since 2008, the glucagon stimulation test (GST) has since been increasingly used in the United States because of its availability, reproducibility, safety, lack of influence by gender and hypothalamic cause of GHD, and relatively few contraindications. In this paper, we discuss our recommendations in performing this test, the potential drawbacks in conducting and caveats in interpreting this test, and its future perspectives.

Postradiation therapy hypopituitarism

The increasing use of radiation treatment for head and neck cancers and other tumors, including pituitary adenomas, from the mid-20th Century onwards led to the recognition that pituitary function may be affected - often leading to some degree of pituitary insufficiency. Our knowledge is mostly based on observational or retrospective rather than randomized prospective studies. The various axes may be impacted at the hypothalamic or pituitary levels, or both. Some axes - the somatotropic and gonadotropic - appear to be especially vulnerable to radiation damage and may be affected quite early, whereas posterior pituitary function is rarely affected. Increased use of stereotactic radiosurgery, which focuses the radiation dose on the abnormal tissue, may be expected to reduce the impact on normal pituitary function, but such studies that are available are, as yet, relatively short term. Prospective studies of the effect of stereotactic radiosurgery on pituitary function would be valuable.

A patient with diabetes insipidus, anterior hypopituitarism and pituitary stalk thickening

BACKGROUND

A 42-year-old woman presented to the neuroendocrine unit of a hospital with recent-onset polydipsia, polyuria and oligomenorrhea. She had no visual symptoms, head injury or history of malignancy.

INVESTIGATIONS

Measurement of serum sodium and osmolality (as well as urine osmolality) after water deprivation, both before and after desmopressin administration. Measurement of basal serum concentrations of pituitary hormones, insulin-like growth factor 1 and thyroid hormone, cosyntropin stimulation testing of adrenal function, and growth-hormone-releasing hormone-arginine stimulation testing. MRI of the pituitary, CT of the chest and abdomen, skeletal surveys, analyses of cerebrospinal fluid, serology and histologic examination of an excised, painful submandibular salivary gland.

DIAGNOSIS

Central diabetes insipidus and anterior hypopituitarism secondary to Langerhans cell histiocytosis.

MANAGEMENT

Replacement therapies, including desmopressin, levothyroxine, cyclic estrogen with medroxyprogesterone, and growth hormone. The stalk lesion remained stable after 7 years without specific therapy.

Vertebral bone marrow fat is positively associated with visceral fat and inversely associated with IGF-1 in obese women

Recent studies have demonstrated an important physiologic link between bone and fat. Bone and fat cells arise from the same mesenchymal precursor cell within bone marrow, capable of differentiation into adipocytes or osteoblasts. Increased BMI appears to protect against osteoporosis. However, recent studies have suggested detrimental effects of visceral fat on bone health. Increased visceral fat may also be associated with decreased growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels which are important for maintenance of bone homeostasis. The purpose of our study was to assess the relationship between vertebral bone marrow fat and trabecular bone mineral density (BMD), abdominal fat depots, GH and IGF-1 in premenopausal women with obesity. We studied 47 premenopausal women of various BMI (range: 18-41 kg/m², mean 30 ± 7 kg/m²) who underwent vertebral bone marrow fat measurement with proton magnetic resonance spectroscopy (1H-MRS), body composition, and trabecular BMD measurement with computed tomography (CT), and GH and IGF-1 levels. Women with high visceral fat had higher bone marrow fat than women with low visceral fat. There was a positive correlation between bone marrow fat and visceral fat, independent of BMD. There was an inverse association between vertebral bone marrow fat and trabecular BMD. Vertebral bone marrow fat was also inversely associated with IGF-1, independent of visceral fat. Our study showed that vertebral bone marrow fat is positively associated with visceral fat and inversely associated with IGF-1 and BMD. This suggests that the detrimental effect of visceral fat on bone health may be mediated in part by IGF-1 as an important regulator of the fat and bone lineage.

The relationship between reduced testosterone, stimulated growth hormone secretion and increased carotid intima-media thickness in obese men

OBJECTIVE

Obesity is associated with reduced testosterone and growth hormone (GH). However, the interrelationship between these axes and their independent contributions to cardiovascular risk is unknown. The objectives of this study were to determine (1) the association between testosterone and GH in obesity, (2) whether excess adiposity mediates this association and (3) the relative contribution of reduced testosterone and GH to increased carotid intima-media thickness (cIMT) in obesity.

DESIGN

Fifty obese men were studied with GH-releasing hormone-arginine testing, and morning free testosterone (FT) was measured by equilibrium dialysis. Metabolic, anthropometric and cardiovascular risk indices, including cIMT were measured. Twenty-six normal weight men served as controls.

RESULTS

Obese subjects demonstrated lower mean (±SEM) peak stimulated GH (5·9 ± 0·6 vs 36·4 ± 3·9 μg/l; P < 0·0001) and FT (0·41 ± 0·03 vs 0·56 ± 0·03 nmol/l; P = 0·0005) compared to controls. GH was significantly associated with FT (r = +0·44; P < 0·0001) and both were inversely related to visceral adipose tissue (VAT) (GH: r = -0·65; P < 0·0001; FT: r = -0·51; P < 0·0001). In multivariate regression analysis controlling for VAT, FT was no longer related to GH. Both GH and FT were associated with cIMT in univariate analysis. However, in multivariate modelling including traditional cardiovascular risk markers, GH (β = 0·003; P = 0·04) but not FT (P = 0·35) was associated with cIMT.

CONCLUSIONS

These results demonstrate a strong relationship between FT and GH in obesity and suggest that this relationship is more a function of excess adiposity rather than a direct relationship. While reduced FT and GH are both related to increased cIMT, the relationship with reduced GH remains significant controlling for reduced FT and traditional cardiovascular disease risk markers.

Growth hormone status predicts left ventricular mass in patients after cure of acromegaly

CONTEXT

Growth hormone excess and growth hormone deficiency (GHD) are both associated with increased cardiovascular morbidity. A specific acromegaly-related cardiomyopathy has been described, characterized in part by increased left ventricular mass (LVM). Growth hormone deficiency is associated with reduced LVM. Following cure of acromegaly with surgery or radiation therapy, GHD may develop; however, its effects on cardiac morphology and function in this population are not established.

OBJECTIVE

We hypothesized that the development of GHD in patients with prior acromegaly would be associated with cardiac morphologic and functional changes that differ from those in patients who are GH sufficient following cure of acromegaly.

DESIGN

A cross-sectional study was conducted in a Clinical Research Center. Study participants consisted of three groups of subjects (n=34): I. Cured acromegaly with GHD (n=15), II. Cured acromegaly with GH sufficiency (n=8), and III. Active acromegaly (n=11). Main outcome measures included cardiac morphology and function, using echocardiography parameters.

RESULTS

Mean age and BMI, 44.6 ± 2.3 years (SEM) and 30.7 ± 1.3 kg/m², respectively, were not different among the three groups. Mean peak GH values were: I. 2.8 ± 0.4 ng/ml; II. 30.1 ± 9.1 ng/ml (p=0.0002.) In group I, left ventricular mass, indexed to body surface area (LVMi), was within the normal range in all patients; moreover, left ventricular (LV) geometry was normal. At least 50% of patients in groups II and III had elevated LVMi, and in 50% of patients, LV geometry was abnormal, indicating pathologic hypertrophy. Ejection fraction was similar between all three groups. There were no significant differences in diastolic function.

CONCLUSIONS

Patients who develop GHD following cure of acromegaly do not demonstrate elevated LV mass, in contrast to patients with a history of acromegaly but normal GH levels or to patients with active acromegaly. This suggests that GH status after treatment of acromegaly correlates with LV mass, and that, in GH sufficient patients, reversal of remodeling may be slower than previously thought. These data suggest that it will be important to determine whether GH replacement alters left ventricular morphology over time.

The diagnosis and treatment of growth hormone deficiency in adults

PURPOSE OF REVIEW

This review summarizes the recent published information regarding efficacy and complications of growth hormone replacement therapy. Several recent reports have monitored patients for periods of up to 10 years. Additionally, a consensus conference has been held regarding needed improvements in diagnostic testing and the recommendations of consensus panels regarding diagnostic criteria and laboratory test utilization are summarized.

RECENT FINDINGS

Long-term studies show growth hormone can be administered safely and that muscle strength and function as well as lipoprotein abnormalities and low-bone mineral density show sustained improvement over extended periods of time. The complications that occur are generally dose-dependent and once attenuated do not tend to recur. Long-term safety studies regarding improvement in cardiovascular mortality and/or worsening prognosis for patients who develop malignancies are available only in the form of observational studies and randomized controlled long-term trial information is not yet available. The studies reported provide a means for clinicians to ascertain the patients who are likely to derive the greatest benefit from growth hormone when the appropriate diagnostic testing and treatment paradigms are utilized.

SUMMARY

The studies that are summarized provide useful information for assessing the response to treatment, selecting patients who are candidates for long-term replacement therapy and for selecting those in whom the need for therapy may need to be reassessed.

Comparative validation of the growth hormone-releasing hormone and arginine test for the diagnosis of adult growth hormone deficiency using a growth hormone assay conforming to recent international recommendations

CONTEXT

The GHRH plus arginine (GHRH+Arg) test is a promising alternative to the insulin tolerance test (ITT) for diagnosis of adult GH deficiency (AGHD).

OBJECTIVES

The objectives of the study were to validate the GHRH+Arg test for diagnosis of AGHD, using the ITT as comparator and a GH assay calibrated according to recent international recommendations, and to study the repeatability and tolerance of both tests.

DESIGN

This was a multicenter, randomized, open-label, phase III study.

SETTING

The study was conducted at 10 French university hospitals.

SUBJECTS

Sixty-nine subjects (38 and 15 with high and low probability of GH deficiency, respectively, and 16 healthy controls) were randomized: 35 to the GHRH+Arg-GHRH+Arg-ITT test sequence and 34 to the ITT-ITT-GHRH+Arg test sequence.

INTERVENTIONS

Each subject underwent three tests of GH secretion separated by 24 h or more.

MAIN OUTCOME MEASURES

The primary variable used for response assessments was serum peak GH response. Test results were compared with the final AGHD diagnosis.

RESULTS

Peak GH responses in the two tests were strongly correlated. A cutoff value of 7.89 microg/liter for GHRH+Arg corresponding to 3 microg/liter for ITT was calculated. The cutoff value leading to 95% specificity with the GHRH+Arg test was measured at about 3.67 microg/liter (sensitivity 79.0%). Intermethod agreement and repeatability were high. Both tests were well tolerated. A preference for the GHRH+Arg test was expressed by 74% of subjects.

CONCLUSIONS

The GHRH+Arg test demonstrated good accuracy and repeatability, was at least as sensitive as the ITT, and was associated with better subject acceptability. The GHRH+Arg test represents a good alternative to the ITT for the diagnosis of AGHD.

Risk factor for pituitary dysfunction in children and adolescents with Rathke's cleft cysts

Purpose

This study evaluated the clinical manifestations of and risk factors for pituitary insufficiency in children and adolescents with Rathke's cleft cysts.

Methods

Forty-four patients with Rathke's cleft cysts younger than 19 years who visited Seoul National University Children's Hospital between January 1995 and September 2009 were enrolled. Rathke's cleft cysts were confirmed histologically through an operation in 15 patients and by brain magnetic resonance imaging (MRI) in 29 patients. The clinical, hormonal, and imaging features were reviewed retrospectively.

Results

The clinical presentation of symptomatic patients was as follows: headache (65%), endocrinopathy (61%), and visual disturbance (19%). Endocrinopathy included central precocious puberty (18%), diabetes insipidus (14%), general weakness (11%), and decreased growth velocity (7%). After surgery, hyperprolactinemia resolved in all patients, but growth hormone insufficiency, hypothyroidism, and diabetes insipidus did not improve. Pituitary insufficiency except gonadotropin abnormality correlated significantly with severe headache, visual disturbance, general weakness, and cystic size. Suprasellar extension of cysts and high signals in the T2-weighted image on brain MRI were related to hypothyroidism, hypocortisolism, and diabetes insipidus. Multivariable linear regression analysis showed that only general weakness was a risk factor for pituitary insufficiency (R²=0.549).

Conclusion

General weakness is a risk factor for pituitary insufficiency in patients with Rathke's cleft cysts. When a patient with a Rathke's cleft cyst complains of general weakness, the clinician should evaluate pituitary function and consider surgical treatment.

The rational use of pituitary stimulation tests

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Insulin like growth factor-I in acute subarachnoid hemorrhage: a prospective cohort study

Introduction

Neuroendocrine deficiencies may affect recovery after aneurysmal subarachnoid hemorrhage (aSAH). Insulin like growth factor-I (IGF-I) regulates neuronal growth and apoptosis in ischemic stroke. Our study was designed to a) characterize the behavior of serum IGF-I and growth hormone (GH) in the acute and late phases after aSAH reflecting possible pituitary gland function and b) evaluate the association between IGF-I and morbidity assessed by Glasgow outcome scale (GOS) and health related quality of life (HRQoL) in patients with aSAH.

Methods

In this prospective cohort study, patients with aSAH (n = 30) were compared to patients who underwent elective aneurysm surgery (n = 16). Serum GH and IGF-I concentrations were measured daily for five (controls) or seven (aSAH) days and at three months. GOS and 15d HRQoL was measured at three months. A mixed models method was used for testing between the groups. For factors possibly affecting HRQoL in aSAH patients, we constructed a Bayesian predicting model using a P-course Bayesian classifier.

Results

The mean IGF-I concentrations for days one to five were 8.1 ± 3.5 nmol/l in patients with aSAH and 11.2 ± 3.1 in the control group (P = 0.01). No corresponding difference was found at three months. Serum GH concentrations were similar in both patient groups. Severity of the aSAH did not affect serum IGF-I concentrations. Patients with GOS ≤ 4 had lower IGF-I concentrations and lower HRQoL than patients with GOS 5 (P = 0.02 and 0.003 respectively). The 15d HRQoL was 0.81 ± 0.16 in patients with aSAH and 0.86 ± 0.09 in control patients (P = 0.24). In the Bayesian model, the use of statins prior to aSAH, hyponatremia, high maximal sequential organ specific score (SOFAmax), and low cumulative IGF-I concentrations on days one to seven were associated with poor HRQoL (accuracy 89%, sensitivity 86%, and specificity 93%).

Conclusions

IGF-I concentrations are low during acute aSAH, which may have an impact on morbidity.

Trial registration

ClinicalTrials.gov Identifier NCT00614887

Hypogonadism on admission to acute rehabilitation is correlated with lower functional status at admission and discharge

PRIMARY OBJECTIVE

To investigate the association between hormone levels and functional status during acute TBI rehabilitation.

RESEARCH DESIGN

Retrospective cohort study of 43 men with moderate-to-severe TBI admitted to an acute rehabilitation unit during a 1 year period.

METHODS AND PROCEDURES

Labs were drawn on admission, including total and free testosterone (T), prolactin, adrenocorticotropin hormone (ACTH), cortisol, thyroid stimulating hormone (TSH), free thyroxine (fT4) and insulin-like growth factor (IGF-1). Functional Independence Measure (FIM) scores were obtained at admission and discharge.

MAIN OUTCOME AND RESULTS

Associations between admission hormone levels and the main outcomes, admission and discharge FIM scores, were assessed using linear regression. Lower total and free T-levels at admission were associated with lower total FIM scores at admission (p < 0.038) and discharge (p < 0.046). Higher cortisol levels at admission were significantly associated with lower admission (p = 0.012) and discharge (p = 0.036) scores on the cognitive-FIM. Prolactin, TSH, fT4 and IGF-1 were not correlated with functional status.

CONCLUSIONS

In men, lower total and free T-levels at admission to acute rehabilitation correlate with lower admission and discharge FIM scores. These data support the need for studies to investigate the impact of physiological testosterone therapy on outcomes during and post-rehabilitation.

Metabolic, cardiovascular, and cerebrovascular outcomes in growth hormone-deficient subjects with previous cushing's disease or non-functioning pituitary adenoma

CONTEXT

Previous exposure to hypercortisolism due to Cushing's disease (CD) may adversely affect long-term metabolic and cardiovascular outcomes. In particular, metabolic and cardiovascular outcomes of patients with previous CD who require GH replacement have not been fully established.

OBJECTIVE

The aim of the study was to compare the prevalence and incidence of metabolic syndrome (Adult Treatment Panel III criteria), diabetes mellitus, cardiovascular disease, and cerebrovascular disease in GH-treated subjects with previous CD with GH-treated subjects with previous nonfunctioning pituitary adenoma (NFPA).

DESIGN

We conducted post hoc analysis of the observational Hypopituitary Control and Complications Study conducted at 362 international centers (1995-2006).

SUBJECTS

We studied adult-onset GH-deficient subjects with previous CD (n = 160) or NFPA (n = 879). All subjects received GH replacement therapy and were GH naive at enrollment. Multiple pituitary deficits were prevalent in both groups.

MAIN OUTCOME MEASURES

We measured the prevalence and incidence of metabolic syndrome, diabetes mellitus, cardiovascular disease, and cerebrovascular disease at baseline and at 3 yr, standardized for age and sex differences between groups.

RESULTS

Compared with subjects with previous NFPA, subjects with previous CD had a significantly greater 3-yr incidence of metabolic syndrome (CD, 23.4%; NFPA, 9.2%; P = 0.01), baseline (CD, 6.3%; NFPA, 2.2%; P < 0.01) and 3-yr (CD, 7.6%; NFPA, 3.9%; P = 0.04) prevalence of cardiovascular disease, and baseline (CD, 6.4%; NFPA, 1.8%; P = 0.03) and 3-yr (CD, 10.2%; NFPA, 2.9%; P = 0.01) prevalence of cerebrovascular disease.

CONCLUSIONS

Previous hypercortisolism may predispose GH-treated, GH-deficient subjects with prior CD to an increased risk of metabolic syndrome, cardiovascular disease, and cerebrovascular disease.

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.

Is there an undiscovered neurocircuit for regulating GH secretion? -Pitfalls of GHRP-2 and ITT as GH provocative tests-

GH secretion is mainly regulated at the hypothalamus by a dual interplay between growth hormone releasing hormone (GHRH) and somatostatin, which are modulated by various factors. We examined the regulatory mechanism of GH secretion in an apparently healthy young man without decreased IGF-1 concentration and nocturnal GH secretion, but who showed low responses to insulin tolerance (ITT) and to GHRP-2 tests. The patient also had no GH response to acute aerobic exercise. However, he had normal secretion of pituitary hormone based on hypothalamic releasing hormone tests combined with CRH, GRH as GHRH, LH-RH and TRH. In addition, he had a GH response without paradoxical secretion to TRH stimulation as well as an ACTH response to subcutaneous glucagon stimulation, and AVP secretion responded to 5% hypertonic saline infusion, though it was not adequately stimulated by ITT. MRI showed no structural abnormalities in the hypothalamus-pituitary gland. These findings indicate that this subject may have an undiscovered neurocircuit for regulating GH secretion, as well as other neurohormones, to maintain homeostasis, even though there were low responses of the hormones to ITT and GHRP-2 stimuli, probably via altered secretion of hypothalamic hormones.

Reduced growth hormone secretion is associated with increased carotid intima-media thickness in obesity

CONTEXT

Obesity is associated with reduced GH.

OBJECTIVE

The aim of the study was to determine whether reduced GH is associated with increased carotid intima-media thickness (cIMT) in obesity.

DESIGN

A total of 102 normal-weight and obese men and women without known hypopituitarism were studied. Subjects underwent GH stimulation testing with GHRH-arginine. Lipid profile, inflammatory markers, oral glucose tolerance test, abdominal computed tomography, dual-energy x-ray absorptiometry, and cIMT were measured. Relative GH deficiency was defined as peak GH of 4.2 microg/liter or less. Subjects were separated based on BMI and GH testing into three groups: normal weight, obese GH sufficient (GHS), and obese relative GH deficient (GHD). Age, gender, and race were similar between the groups. BMI, percentage body fat, and visceral adiposity did not differ between obese GHS and relative GHD.

RESULTS

Peak GH was associated with cIMT, IGF-I, high-density lipoprotein, low-density lipoprotein, triglycerides, adiponectin, C-reactive protein, and TNF-alpha (all P < 0.05). Obese GHS subjects had similar cIMT compared to normal-weight subjects (P = not significant), whereas obese GHD subjects had higher cIMT compared to normal-weight subjects (P < 0.05) (normal weight, 0.645 +/- 0.023, vs. obese GHS, 0.719 +/- 0.021, vs. obese GHD, 0.795 +/- 0.063 mm; P = 0.01 by ANOVA). Similar results were seen in sensitivity analyses with less stringent cutoffs (< 5, < or = 8, < 9 microg/liter) to define GHD. In multivariate modeling, peak GH remained significantly associated with cIMT after controlling for age, gender, race, tobacco, blood pressure, cholesterol, and fasting glucose (R(2) for model, 0.35; P < 0.0001).

CONCLUSIONS

These results suggest that reduced GH secretion is associated with a more abnormal metabolic phenotype in obesity, characterized by increased cIMT, dyslipidemia, insulin resistance, and inflammation.

A reappraisal of diagnosing GH deficiency in adults: role of gender, age, waist circumference, and body mass index

OBJECTIVE

The objective of the study was to reevaluate the diagnostic accuracy of GH peak after GHRH plus arginine test (GHRH+ARG) according to patients' age, body mass index (BMI), and waist circumference to diagnose GH deficiency (GHD).

OUTCOME MEASURES

GH peak after GHRH+ARG and IGF-I levels reported as sd score.

SUBJECTS

Subjects included 408 controls (218 women, 190 men, aged 15-80 yr) and 374 patients with hypopituitarism (167 women, 207 men, aged 16-83 yr).

RESULTS

In the (elderly) healthy subjects 15-25 yr old (young), 26-65 yr old (adults) and older than 65 yr, GH cutoffs were 15.6, 11.7, and 8.5 microg/liter, 11.8, 8.1, and 5.5 microg/liter, and 9.2, 6.1, and 4.0 microg/liter, respectively, in the lean, overweight, and obese subjects. Waist circumference was the best predictor of GH peak (t = -7.6, P < 0.0001) followed by BMI (t = -6.7, P < 0.0001) and age (t = -5.7, P < 0.0001). Based on the old (<9.1 microg/liter) and new GH cutoff, 286 (76.5%) and 276 (73.8%) of 374 hypopituitary patients had severe GHD. The receiving-operator characteristic analysis showed GH cutoffs in line with the third percentile or slightly higher results so that the prevalence of GHD increased to 90.1%.

CONCLUSIONS

The results of the current study show that waist circumference and BMI are the strongest predictors of GH peak after GHRH+ARG followed by age. However, the old cutoff value of 9.0 microg/liter was in line with the new cutoffs in 95% of patients.

Peak growth hormone-releasing hormone-arginine-stimulated growth hormone is inversely associated with intramyocellular and intrahepatic lipid content in premenopausal women with obesity

CONTEXT

Visceral adiposity is a strong determinant of GH secretion, and low endogenous GH secretion is associated with increased insulin resistance, a key component of the metabolic syndrome. Increased fat accumulation in skeletal muscle and liver may play an etiological role in the development of insulin resistance and other complications of the metabolic syndrome. Little is known about the role of decreased endogenous GH secretion in the pathogenesis of insulin resistance in obesity.

OBJECTIVE

To investigate the relationship between intramyocellular lipids (IMCL), intrahepatic lipids, and peak-stimulated GH in premenopausal women with obesity.

DESIGN AND SETTING

We conducted a cross-sectional study at a clinical translational research center.

PATIENTS

Patients included 21 premenopausal women with obesity (mean body mass index, 34.0 +/- 4.5 kg/m(2)) and 17 normal-weight controls (mean body mass index, 21.9 +/- 2.0 kg/m(2)) of comparable mean age.

MAIN OUTCOMES MEASURES

IMCL and intrahepatic lipids were measured with proton magnetic resonance spectroscopy ((1)H-MRS). Body composition was measured with magnetic resonance imaging. Peak GH was measured after stimulation with GHRH-arginine.

RESULTS

Obese subjects had higher IMCL, intrahepatic lipids, abdominal and thigh fat, and thigh muscle mass compared with normal-weight controls. There were strong inverse associations between peak GH and both IMCL and intrahepatic lipids independent of age and visceral adiposity. There were positive associations between IMCL and intrahepatic lipids with measures of insulin resistance and serum triglycerides.

CONCLUSION

In premenopausal women with obesity, peak GH is inversely associated with IMCL and intrahepatic lipids independent of age and visceral adiposity. This suggests that low GH may contribute to insulin resistance in obesity through effects on muscle and intrahepatic lipids.

Clinical review: Is lack of recombinant growth hormone (GH)-releasing hormone in the United States a setback or time to consider glucagon testing for adult GH deficiency?

CONTEXT

The use of the combined GHRH and arginine (GHRH-ARG) test has gained increasing acceptance in the United States as a reliable alternative test to the insulin tolerance test (ITT) for diagnosing adult GH deficiency (GHD). In July 2008, the only manufacturer of recombinant GHRH in the United States, EMD Serono, Inc., announced the discontinuation of Geref, thus raising the question of which reliable alternative GH stimulation test should practicing endocrinologists be considering in place of the GHRH-ARG test. In this article, we review the existing published data and consensus guidelines and provide recommendations for alternative stimulation tests to the GHRH-ARG test.

EVIDENCE ACQUISITION

The major source of data acquisition included PubMed search strategies and personal experience of the authors from clinical experience.

EVIDENCE SYNTHESIS

Previous consensus guidelines and previous data assessing the reliability and discriminatory value of the GHRH-ARG, glucagon, ARG, and GH secretagogues on assessing GH reserve are discussed. Our recommendations for performing the glucagon stimulation test, potential drawbacks in conducting this test, and caveats in interpreting this test are also discussed.

CONCLUSIONS

The ITT should remain the test of choice in diagnosing adult GHD. However, when the ITT is not desirable and recombinant GHRH remains unavailable in the United States, we recommend the alternative to the GHRH-ARG test to be the glucagon stimulation test, based on its reliability and availability. Nevertheless, further studies into alternative GH stimulation tests that are available in the United States, comparable, and simpler to perform than the ITT in diagnosing adult GHD are still needed.

Relative growth hormone deficiency and cortisol excess are associated with increased cardiovascular risk markers in obese adolescent girls

CONTEXT

Obesity in adolescents is increasingly prevalent and its impact on cardiovascular risk important to determine. Hormonal predictors of cardiovascular risk markers in obese adolescents are not known.

OBJECTIVE

Our objective was to examine whether relative GH deficiency and cortisol excess are determinants of increased cardiovascular risk markers in obese teenage girls.

DESIGN AND SETTING

A cross-sectional study was conducted at a clinical research center.

STUDY PARTICIPANTS

Thirty girls (15 obese girls and 15 normal-weight controls) 12-18 years old matched for maturity and race.

MAIN OUTCOME MEASURES

Inflammatory markers of cardiovascular risk including high-sensitivity C-reactive protein (hsCRP), TNF-alpha receptors 1 and 2, E-selectin, soluble intercellular adhesion molecule-1, and IL-6 were analyzed. Leptin, adiponectin, and 24-h urine free cortisol (UFC) were also measured. A GHRH-arginine stimulation test was performed.

RESULTS

The hsCRP levels were higher in obese girls than controls (4.63 +/- 4.81 vs. 0.67 +/- 0.72 mg/liter; P = 0.002 after log conversion), as were other markers of cardiovascular risk. Eight of the 15 obese girls but no normal-weight girl had hsCRP higher than 3 mg/liter (P = 0.002). Body mass index sd score was higher than 4.0 in 87.5% of girls with hsCRP higher than 3 mg/liter and no girls with hsCRP less than 3 mg/liter. Girls with hsCRP higher than 3 mg/liter had higher UFC and lower peak GH compared with those with hsCRP less than 3 mg/liter. Peak GH was an important negative predictor of most markers of increased cardiovascular risk. In addition to peak GH, UFC and adiponectin independently predicted hsCRP.

CONCLUSION

Relative GH deficiency and cortisol excess are significant contributors to increased levels of markers of cardiovascular risk in obese adolescent girls.

Relationship between growth hormone/insulin-like growth factor-1 axis integrity and voluntary weight loss after gastric banding surgery for severe obesity

BACKGROUND

The aim of this observational study was to determine, in a retrospective analysis, whether growth hormone (GH) and insulin-like growth factor-1 (IGF-1) at baseline or changes in the GH/IGF-1 axis after laparoscopic adjustable gastric banding (LAGB) is associated with weight loss and body composition changes in severely obese nondiabetic patients.

METHODS

Weight loss (expressed as percent excess weight loss [EWL%]), anthropometry, body composition by bioelectrical impedance analysis (BIA), serum IGF-1, and GH peak after GH-releasing hormone (GHRH) plus arginine (ARG) test were measured and expressed as standard deviation scores (SDS) of reference values in 104 women and 36 men, age (mean +/- SD) 34 +/- 11 and 30.2 +/- 11 years, and BMI 44 +/- 5.7 and 39 +/- 3.2, respectively, before and 6 months after LAGB.

RESULTS

After LAGB, 25% of women and 22.5% of men had GH deficiency, while 30.8% of women and 33.3% of men had IGF-1 deficiency or insufficiency. The median EWL was 36.8% in women and 40.0% in men. In both genders, percent decrease of waist circumference, EWL, and fat mass (FM) and percent increase of fat-free mass (FFM) was greater in patients with normal GH secretion and IGF-1 levels. The GH peak after GHRH + ARG, IGF-1 levels, and IGF-1 SDS were inversely correlated with EWL% (r = -0.50, r = -0.53, and r = -0.42, respectively; p < 0.0001) and percent FM (r = -0.41, r = -0.36, and r = -0.35, respectively; p < 0.0001). In stepwise linear regression analysis, the GH peak after GHRH + ARG was the major determinant of EWL% (p < 0.0001) and FM (p = 0.001).

CONCLUSIONS

The efficacy of LAGB was greater in the patients with a normal GH response to GHRH + ARG and with normal IGF-1 levels. The percent of FM, FFM, and EWL were significantly correlated with the GH response to GHRH + ARG and with IGF-1 levels.

Anterior hypopituitarism following traumatic brain injury

PRIMARY OBJECTIVES

To review evidence that there exists a substantial sub-population of patients with endocrine disorders as a result of traumatic brain injury (TBI) and to underscore the importance of screening patients with TBI considered most at risk for hypopituitarism with the goal of attaining beneficial effects in terms of morbidity and quality of life.

DESIGN AND METHODS

Reviewed recent literature regarding the frequency of TBI-induced hypopituitarism.

MAIN OUTCOMES AND RESULTS

Studies by Kelly DF, Gaw Gonzalo IT, Cohan P, et al. Hypopituitarism following traumatic brain injury and aneurysmal subarachnoid hemorrhage: A preliminary report. Journal of Neurosurgery 2000;93:743-751, Lieberman SA, Oberoi AL, Gilkison CR, et al. Prevalence of neuroendocrine dysfunction in patients recovering from traumatic brain injury. Journal of Clinical Endocrinology and Metabolism 2001;86:2752-2756 and Aimaretti G, Ambrosio MR, Di Somma C, et al. Traumatic brain injury and subarachnoid haemorrhage are conditions at high risk for hypopituitarism. Screening study at 3 months after the brain injury, In press., found that about one-half to one-third of patients with TBI had anterior pituitary hormone deficiencies, including growth hormone (GH) deficiency in 15-21%, and subtle deficiencies in thyroid, adrenal and gonadal axes. One or more hormonal deficiencies produce diverse physical and psychological symptoms that may mimic symptoms attributed to brain trauma and may impair rehabilitation. A more general concern is the fact that hypopituitarism increases the risk of significant morbidity (e.g. ischaemic heart disease) and mortality (shortened life span).

CONCLUSIONS

To attain maximal improvement in mental and physical functioning as well as in quality of life for victims of TBI, it is crucial that anterior pituitary hormonal function be assessed. Appropriate hormone replacement therapy for those patients with both TBI and TBI-induced pituitary function impairment could, for the first time, allow treatment and correction of underlying causes of TBI sequelae rather than merely symptomatic treatment.

Growth hormone deficiency is associated with decreased quality of life in patients with prior acromegaly

CONTEXT

Both GH deficiency (GHD) and GH excess are associated with a decreased quality of life. However, it is unknown whether patients with GHD after treatment for acromegaly have a poorer quality of life than those with normal GH levels after cure of acromegaly.

OBJECTIVE

The aim of the study was to determine whether patients with GHD and prior acromegaly have a poorer quality of life than those with GH sufficiency after cure of acromegaly.

DESIGN AND SETTING

We conducted a cross-sectional study in a General Clinical Research Center.

STUDY PARTICIPANTS

Forty-five patients with prior acromegaly participated: 26 with GHD and 19 with GH sufficiency.

INTERVENTION

There were no interventions.

MAIN OUTCOME MEASURES

We evaluated quality of life, as measured by 1) the Quality of Life Adult Growth Hormone Deficiency Assessment (QoL-AGHDA); 2) the Short-Form Health Survey (SF-36); and 3) the Symptom Questionnaire.

RESULTS

Mean scores on all subscales of all questionnaires, except for the anger/hostility and anxiety subscales of the Symptom Questionnaire, showed significantly impaired quality of life in the GH-deficient group compared with the GH-sufficient group. Peak GH levels after GHRH-arginine stimulation levels were inversely associated with QoL-AGHDA scale scores (R = -0.53; P = 0.0005) and the Symptom Questionnaire Depression subscale scores (R = -0.35; P = 0.031) and positively associated with most SF-36 subscale scores.

CONCLUSIONS

Our data are the first to demonstrate a reduced quality of life in patients who develop GHD after cure of acromegaly compared to those who are GH sufficient. Further studies are warranted to determine whether GH replacement would improve quality of life for patients with GHD after cure from acromegaly.

Changing patterns of the adult growth hormone deficiency diagnosis documented in a decade-long global surveillance database

BACKGROUND

GH therapy in adult patients with GH deficiency (GHD) was approved over 10 yr ago, and the indication has subsequently gained broad acceptance. The HypoCCS surveillance database is a suitable means to examine the evolution of diagnostic patterns since 1996.

METHODS

Baseline demographics, reported cause of GHD, and diagnostic tests were available from 5893 GH-treated patients. Trends for change over time in diagnosis, GH stimulation test data, and IGF-I measurements were analyzed at 2-yr intervals by linear regression models, with entry year as the predictive variable.

RESULTS

Over the decade, there was a decrease in patients enrolled with diagnoses of pituitary adenoma (50.2 to 38.6%; P < 0.001), craniopharyngioma (13.3 to 8.4%; P = 0.005) and pituitary hemorrhage (5.8 to 2.8%; P = 0.001); increases in idiopathic GHD (13.9 to 19.3%; P < 0.001), less common diagnoses (7.4 to 15.8%; P < 0.001), and undefined/unknown diagnoses (1.3 to 8.6%; P < 0.001) were observed. Use of arginine, clonidine, and L-dopa tests declined, whereas use of the GHRH-arginine test increased. Median values for peak GH from all tests except GHRH-arginine and for IGF-I SD scores increased significantly (P < 0.001). Over the decade (1996--2005), idiopathic GHD was reported for 16.7% of patients, and more than half of these had adult onset GHD. In the idiopathic adult onset group, 40.2% had isolated GHD; 18.3 and 4.4% had a stimulation test GH peak of at least 3.0 and 5.0 microg/liter, respectively.

CONCLUSIONS

Significant shifts in diagnostic patterns have occurred since approval of the adult GHD indication, with a trend to less severe forms of GHD.

Bone mineral density in young adult survivors of acute lymphoblastic leukemia

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Impaired IGF1-GH axis and new therapeutic options in Alström Syndrome patients: a case series

Background

Defects of the primary cilium and its anchoring structure, the basal body, cause a number of human genetic disorders, collectively termed ciliopathies: primary ciliary dyskinesia, Bardet-Biedl syndrome, polycystic kidney and liver disease, nephronophthisis, Alström syndrome, Meckel-Gruber syndrome and some forms of retinal degeneration.

Alström syndrome is an extremely rare, autosomal recessive genetic disorder characterized by a group of signs and symptoms including infantile onset dilated cardiomyopathy, blindness, hearing impairment/loss, obesity, diabetes, hepatic and renal dysfunction.

Because adult growth hormone deficiency and Alström Syndrome share some clinical and metabolic features, we studied the GH-IGF1 axis, using MRI techniques and dynamic tests in 3 unrelated patients with Alström syndrome.

Case presentation

The patients were hospitalized and the growth hormone stimulatory tests were made, as well as brain MRI. Insulin provocative test revealed a severe GH deficiency in these patients, defined by a peak response to insulin-induced hypoglycemia less than 3 ng/dl and IGF1 concentrations less than – 2SDS.

We didn't find multiple pituitary hormone deficiency and we noticed only a severe GH deficiency in all three patients. The MRI study of the diencephalic and pituitary region was suggestive for the diagnosis of empty sella in one patient.

One patient received Recombinant-GH replacement for one year with very good results, one underwent a gastric sleeve with a satisfactory outcome, one patient died due to the progression of the cardiac myopathy.

Conclusion

Future studies are needed to assses if the substitution therapy with Recombinant Growth hormone is cost-effective and without risk in such patients with Alström Syndrome and severe insulin resistance, despite our good results in one patient. Also, careful clinical and genetic studies can contribute to a better understanding of the evolution after different therapeutical attempt in the complex disorders such as Alström Syndrome.

Hypopituitarism following radiotherapy

Deficiencies in anterior pituitary hormones secretion ranging from subtle to complete occur following radiation damage to the hypothalamic-pituitary (h-p) axis, the severity and frequency of which correlate with the total radiation dose delivered to the h-p axis and the length of follow up. Selective radiosensitivity of the neuroendocrine axes, with the GH axis being the most vulnerable, accounts for the high frequency of GH deficiency, which usually occurs in isolation following irradiation of the h-p axis with doses less than 30 Gy. With higher radiation doses (30-50 Gy), however, the frequency of GH insufficiency substantially increases and can be as high as 50-100%. Compensatory hyperstimulation of a partially damaged h-p axis may restore normality of spontaneous GH secretion in the context of reduced but normal stimulated responses; at its extreme, endogenous hyperstimulation may limit further stimulation by insulin-induced hypoglycaemia resulting in subnormal GH responses despite normality of spontaneous GH secretion in adults. In children, failure of the hyperstimulated partially damaged h-p axis to meet the increased demands for GH during growth and puberty may explain what has previously been described as radiation-induced GH neurosecretory dysfunction and, unlike in adults, the ITT remains the gold standard for assessing h-p functional reserve. Thyroid-stimulating hormone (TSH) and ACTH deficiency occur after intensive irradiation only (>50 Gy) with a long-term cumulative frequency of 3-6%. Abnormalities in gonadotrophin secretion are dose-dependent; precocious puberty can occur after radiation dose less than 30 Gy in girls only, and in both sexes equally with a radiation dose of 30-50 Gy. Gonadotrophin deficiency occurs infrequently and is usually a long-term complication following a minimum radiation dose of 30 Gy. Hyperprolactinemia, due to hypothalamic damage leading to reduced dopamine release, has been described in both sexes and all ages but is mostly seen in young women after intensive irradiation and is usually subclinical. A much higher incidence of gonadotrophin, ACTH and TSH deficiencies (30-60% after 10 years) occur after more intensive irradiation (>60 Gy) used for nasopharyngeal carcinomas and tumors of the skull base, and following conventional irradiation (30-50 Gy) for pituitary tumors. The frequency of hypopituitarism following stereotactic radiotherapy for pituitary tumors is mostly seen after long-term follow up and is similar to that following conventional irradiation. Radiation-induced anterior pituitary hormone deficiencies are irreversible and progressive. Regular testing is mandatory to ensure timely diagnosis and early hormone replacement therapy.

Anthropometry, CT, and DXA as predictors of GH deficiency in premenopausal women: ROC curve analysis

Visceral adiposity is a strong determinant of growth hormone (GH) secretion, and states of GH deficiency are associated with increased visceral adiposity and decreased lean body mass. The purpose of our study was to determine the sensitivity and specificity of different methods of assessing body composition [anthropometry, dual-energy X-ray absorptiometry (DXA), and computed tomography (CT)] to predict GH deficiency in premenopausal women and threshold values for each technique to predict GH deficiency, using receiver operator characteristic (ROC) curve analysis. We studied a group of 45 healthy lean, overweight, and obese premenopausal women who underwent anthropometric measurements (body mass index, waist and hip circumferences, skin fold thickness), DXA, CT, and a GH-releasing hormone-arginine stimulation test. ROC curve analysis was used to determine cutoff values for each method to identify GH deficiency. Visceral adiposity measured by CT showed the highest sensitivity and specificity for identifying subjects with GH deficiency with a cutoff of >9,962 mm(2) [area under the curve (AUC), 0.95; sensitivity, 100%; specificity, 77.8%; P = 0.0001]. Largest waist circumference showed high sensitivity and specificity with a cutoff of >101.7 cm (AUC, 0.89; sensitivity, 88.9%; specificity, 75%; P = 0.0001). When the ROC curves of visceral fat measured by CT and largest waist circumference were compared, the difference between the two methods was not statistically significant (P = 0.36). Our study showed that the largest waist circumference predicts the presence of GH deficiency in healthy premenopausal women with high sensitivity and specificity and nearly as well as CT measurement of visceral adiposity. It can be used to identify women in whom GH deficiency is likely and therefore in whom formal GH stimulation testing might be indicated.

Androgens may mediate a relative preservation of IGF-I levels in overweight and obese women despite reduced growth hormone secretion

CONTEXT

Obesity is characterized by reduced GH secretion, but data regarding IGF-I levels and their determinants are conflicting.

OBJECTIVES

The objectives were to determine whether IGF-I levels are reduced and to investigate determinants of GH and IGF-I in healthy overweight and obese women.

DESIGN

A cross-sectional study was performed.

SETTING

The study was conducted at a General Clinical Research Center.

STUDY PARTICIPANTS

Thirty-four healthy women without pituitary/hypothalamic disease participated, including 11 lean [body mass index (BMI) <25 kg/m(2)], 12 overweight (BMI > or =25 kg/m(2) and <30 kg/m(2)), and 11 obese (BMI > or =30 kg/m(2)) women of comparable age (overall mean age, 30.7 +/- 7.8 yr).

INTERVENTION

There was no intervention.

MAIN OUTCOME MEASURES

The main outcome measures were frequent sampling (every 10 min for 24 h) for GH, peak GH after GHRH-arginine stimulation, IGF-I, IGF binding protein-3, estrone, estradiol, testosterone, free testosterone, SHBG, homeostasis model assessment of insulin resistance, and abdominal fat.

RESULTS

Mean 24-h GH and peak stimulated GH were lower in overweight than lean women and lowest in obese women. Mean IGF-I levels trended lower in obese, but not overweight, compared with lean women. Free testosterone was positively associated with IGF-I (R = 0.36, P = 0.04) but not with GH measures. Visceral fat was the only determinant of mean 24-h GH (R(2) = 0.66, P < 0.0001) and of peak stimulated GH (R(2) = 0.63, P < 0.0001), and mean 24-h GH accounted for 39% of the variability of IGF-I (P = 0.0002), with an additional 28% (P < 0.0001) attributable to free testosterone levels.

CONCLUSIONS

Despite a linear decrease in GH secretion and peak stimulated GH levels with increasing BMI in healthy overweight and obese women, IGF-I levels were not commensurately reduced. Androgens may contribute to this relative preservation of IGF-I secretion in overweight and obese women despite reduced GH secretion.

Evaluation of permanent growth hormone deficiency (GHD) in young adults with childhood onset GHD: a multicenter study

BACKGROUND

Reconfirming the diagnosis of childhood onset growth hormone deficiency (GHD) in young adults is necessary to demonstrate the need for continuation of GH therapy.

OBJECTIVE

This nationally-based study was planned to establish GH status during adulthood in childhood-onset GH deficient patients and to evaluate factors that would predict persistency of the GHD.

METHODS

In this multicenter study, 70 GH deficient patients who had reached final height were evaluated after completion of GH treatment. Fifty-two patients (74%) had isolated GHD and 18 patients (26%) had multiple pituitary hormone deficiency (MPHD). Patients who had reached final height and the pubertal Tanner stage 5 were reevaluated for GH status. After at least 6 weeks of cessation of GH treatment, patients were retested with insulin induced hypoglycemia.

RESULTS

GHD was found to be transient in 64.3% of all patients. Of the isolated GH deficient patients 82.7% had transient GHD, whereas 88.9% of the MPHD patients showed persistent GHD. Comparison of isolated GH deficient and multiple hormone deficient patients indicated higher peak GH, IGF-I and IGFBP-3 levels in isolated GH deficient patients. No parameter was significantly different in the transiently and persistently GH deficient patients with respect to gender. Although specificity of IGF-I value of less than -2 SD showing persistency of GHD was lower than the specificity of IGFBP-3 value of less than -2 SD (65.7% vs 84%), negative predictive values were similar for the two parameters (85.2% and 84%, respectively).

CONCLUSION

Most of the cases of childhood onset GHD are idiopathic and the GHD is transient. In patients with MPHD, GHD is generally permanent. Low IGF-I and IGFBP-3 levels are supporting findings to show persistency of the GHD.

Prevalence of GH and other anterior pituitary hormone deficiencies in adults with nonsecreting pituitary microadenomas and normal serum IGF-1 levels

OBJECTIVE

GH is usually the first pituitary hormone to be affected following a pathological insult to the pituitary; however, data on the prevalence of GH deficiency in patients with nonsecreting pituitary microadenomas and normal serum IGF-1 levels are scarce. This study aims to evaluate the prevalence of GH and other anterior pituitary hormone deficiencies, and to determine whether microadenomas per se could be associated with reduced GH response rates to GHRH-arginine stimulation.

DESIGN

Analytical, retrospective, two-site case-control study.

PATIENTS AND METHODS

Thirty-eight patients with nonsecreting pituitary microadenomas (mean size 4.2 mm) and normal serum IGF-1 levels were studied. Anterior pituitary function testing, including the GHRH-arginine test to examine GH reserve, was performed in all patients. Serum IGF-1 levels and peak GH levels in the patients that passed the GHRH-arginine test were compared with 22 age- and BMI-matched healthy controls.

RESULTS

Nineteen patients (50%) failed the GHRH-arginine test and had higher body mass index (BMI) than those that passed the GHRH-arginine test and healthy controls. Peak GH levels in patients that passed the GHRH-arginine test were lower compared to healthy controls and 19 patients (50%) had at least one other pituitary hormone deficit. A negative correlation (r = -0.42, P < 0.01) between peak GH levels and BMI was identified, but no correlations were found between peak GH and serum IGF-1 levels.

CONCLUSIONS

Our data demonstrated that a substantial number of patients with nonsecreting pituitary microadenomas failed the GHRH-arginine test despite normal serum IGF-1 levels, and had at least one other pituitary hormone deficiency, suggesting that nonsecreting microadenomas may not be clinically harmless. We therefore recommend long-term follow-up with periodic basal pituitary function testing, and to consider dynamic pituitary testing should clinical symptoms arise in these patients.

Lower growth hormone and higher cortisol are associated with greater visceral adiposity, intramyocellular lipids, and insulin resistance in overweight girls

Although body composition, insulin sensitivity, and lipids are markedly altered in overweight adolescents, hormonal associations with these parameters have not been well characterized. Growth hormone (GH) deficiency and hypercortisolemia predispose to abdominal adiposity and insulin resistance, and GH secretion is decreased in obese adults. We hypothesized that low-peak GH on the GH-releasing hormone (GHRH)-arginine stimulation test and high cortisol in overweight adolescents would be associated with higher regional fat, insulin resistance, and lipids. We examined the following parameters in 15 overweight and 15 bone age-matched control 12- to 18-yr-old girls: 1) body composition using dual-energy X-ray absorptiometry and MR [visceral and subcutaneous adipose tissue at L(4)-L(5) and soleus intramyocellular lipid ((1)H-MR spectroscopy)], 2) peak GH on the GHRH-arginine stimulation test, 3) mean overnight GH and cortisol, 4) 24-h urinary free cortisol (UFC), 5) fasting lipids, and 6) an oral glucose tolerance test. Stepwise regression was the major tool employed to determine relationships between measured parameters. Log peak GH on the GHRH-arginine test was lower (P = 0.03) and log UFC was higher (P = 0.02) in overweight girls. Log mean cortisol (overnight sampling) was associated positively with subcutaneous adipose tissue and, with body mass index standard deviation score, accounted for 92% of its variability, whereas log peak GH and body mass index standard deviation score accounted for 88% of visceral adipose tissue variability and log peak GH for 34% of the intramyocellular lipid variability. Log mean cortisol was independently associated with log homeostasis model assessment of insulin resistance, LDL, and HDL and explained 49-59% of the variability. Our data indicate that lower peak GH and higher UFC in overweight girls are associated with visceral adiposity, insulin resistance, and lipids.

[Management of the growth hormone (GH)-treated patients with diagnosis of GH deficiency (DGH) during transition from childhood to adulthood]

Growth hormone (GH) has many beneficial effects in patients with childhood-onset GH deficiency (GHD) in addition to its promotion of linear growth. The discontinuation of GH treatment in GHD patients, during the transition from childhood to adulthood, induces significant unfavorable changes in body composition, skeletal integrity, exercise capacity, and an adverse cardiovascular risk profile. These changes are reversed after the resumption of GH treatment. As the benefits of continuing GH therapy into adulthood has been well established, it is possible that GH replacement therapy will not be stopped once growth has been completed, but it will continue into adult life. Considering that a high proportion of patients with diagnosis of DGH in childhood are no longer GHD in adolescence, the GH status must be retested when growth is completed. Other factors such as clinical history, GH response in childhood, hipotalamic-pituitary MRI and IGF-1 concentration must be considered. Reconfirmation of GHD diagnosis through stimulation testing is usually required, unless there is a proven genetic or structural lesion persistent from childhood.

Growth hormone deficiency by growth hormone releasing hormone-arginine testing criteria predicts increased cardiovascular risk markers in normal young overweight and obese women

CONTEXT

Little is known about the relationship between GH and cardiovascular risk markers in women without organic hypothalamic/pituitary disease.

OBJECTIVE

The objective of the study was to determine whether healthy young overweight and obese women, who would be classified as having GH deficiency (GHD) based on standard criteria used in hypopituitarism (peak GH after stimulation with GHRH and arginine < 5 ng/ml), have increased cardiovascular risk markers.

DESIGN

This was a cross-sectional study.

SETTING

The study was conducted at the General Clinical Research Center.

STUDY PARTICIPANTS

Forty-five women of reproductive age, mean age 33.1 +/- 1.2 yr and mean body mass index (BMI) 30.9 +/- 1.0 kg/m(2).

INTERVENTION

There was no intervention.

MAIN OUTCOME MEASURES

Measures included carotid intima-medial thickness, high-sensitivity C-reactive protein (hsCRP), total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein, triglycerides, E-selectin, soluble intercellular adhesion molecule-1, TNF-alpha receptor I, TNF-alpha receptor II, fasting insulin levels, and oral glucose tolerance testing.

RESULTS

Twenty-six percent of overweight or obese subjects and none with BMI less than 25 kg/m(2) met criteria for GHD. Subjects who met GHD criteria had a mean BMI of 37.0 +/- 1.7 kg/m(2) (range 28.6-43.6 kg/m(2)), and their mean waist circumference (110.1 +/- 3.5 cm) was higher than in overweight/obese women with GH sufficiency (P = 0.007). Mean carotid intima-media thickness, hsCRP, soluble intercellular adhesion molecule-1, TNF-alpha receptor I, and TNF-alpha receptor II levels were higher, and HDL lower, in women meeting GHD criteria than in GH sufficiency. Differences in HDL, hsCRP, and TNF-alpha receptor II remained after controlling for age plus BMI, waist circumference, or trunk fat. There were no differences in measures of insulin resistance.

CONCLUSIONS

There may be a relative GHD syndrome in overweight and obese women without organic pituitary or hypothalamic disease that confers increased cardiovascular risk, independent of weight.

Growth hormone decreases visceral fat and improves cardiovascular risk markers in women with hypopituitarism: a randomized, placebo-controlled study

CONTEXT

Data regarding gender-specific efficacy of GH on critical endpoints are lacking. There are no randomized, placebo-controlled studies of physiological GH therapy solely in women.

OBJECTIVE

Our objective was to determine the effects of physiological GH replacement on cardiovascular risk markers and body composition in women with GH deficiency (GHD).

DESIGN

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

SETTING

The study was conducted at the General Clinical Research Center.

STUDY PARTICIPANTS

43 women with GHD due to hypopituitarism were included in the study.

INTERVENTION

Study participants were randomized to receive GH (goal mid-normal serum IGF-1) or placebo.

MAIN OUTCOME MEASURES

Cardiovascular risk markers, including high-sensitivity C-reactive protein, tissue plasminogen activator, and body composition, including visceral adipose tissue by cross-sectional computed tomography, were measured.

RESULTS

Mean daily GH dose was 0.67 mg. The mean IGF-1 sd score increased from -2.5 +/- 0.3 to -1.4 +/- 0.9 (GH) (P < 0.0001 vs. placebo). High-sensitivity C-reactive protein decreased by 38.2 +/- 9.6% (GH) vs.18.2 +/- 6.0% (placebo) (P = 0.03). Tissue plasminogen activator and total cholesterol decreased, and high-density lipoprotein increased. Homeostasis model assessment-insulin resistance and other markers were unchanged. Body fat decreased [-5.1 +/- 2.0 (GH) vs. 1.9 +/- 1.0% (placebo); P = 0.002] as did visceral adipose tissue [-9.0 +/- 5.9 (GH) vs. 4.3 +/- 2.7% (placebo); P = 0.03]. Change in IGF-1 level was inversely associated with percent change in visceral adipose tissue (r = -0.61; P = 0.002), total body fat (r = -0.69; P < 0.0001), and high-sensitivity C-reactive protein (r = -0.51; P = 0.003).

CONCLUSIONS

Low-dose GH replacement in women with GHD decreased total and visceral adipose tissue and improved cardiovascular markers, with a relatively modest increase in IGF-1 levels and without worsening insulin resistance.

Effects of oral ingestion of amino acids and proteins on the somatotropic axis

CONTEXT

GH is an important regulator of growth and body composition. It has been shown that GH release can be promoted by iv as well as oral administration of various amino acids (AAs), especially arginine (ARG) and lysine (LYS), which are amply present in soy protein. However, the effects of dietary protein on GH secretion are less well described.

OBJECTIVE AND DESIGN

In an experiment, we compared the effects of oral ingestion of a mixture reflecting the AA composition of soy protein (AA), with oral ingestion of ARG + LYS, on GH secretion in eight healthy women (body mass index 19-25 kg/m(2); age, 18-24 yr). In a second experiment, we compared oral ingestion of hydrolyzed soy protein and complete soy protein with the AA mixture on GH secretion in eight healthy women (body mass index 19-26 kg/m(2); age, 19-36 yr). Both experiments were performed in a randomized, single-blind crossover design. GH, insulin, glucose, and plasma AA were determined every 20 min, during 3 h in the first experiment and during 5 h in the second experiment.

RESULTS

Peak values of GH were higher after ingestion of the AA mixture compared with ingestion of ARG + LYS (P < 0.05). GH responses, as determined by area under the curve, did not significantly differ after ingestion of the complete soy protein, hydrolyzed soy protein, or AA mixture but were all higher than after placebo (P < 0.05). Insulin responses (area under the curve) were higher after ingestion of hydrolyzed soy protein, complete soy protein, and AA mixture, compared with placebo (P < 0.05). Glucose concentrations were unaffected.

CONCLUSION

Ingestion of soy protein, either hydrolyzed or intact, as well as AAs reflecting soy protein, stimulates GH release to a similar extent.

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.

Postoperative assessment of the patient after transsphenoidal pituitary surgery

While most transsphenoidal pituitary surgery is accomplished without complication, monitoring is required postoperatively for a set of disorders that are specific to this surgery. Postoperative assessments are tailored to the early and later postoperative periods. In the early period, which spans the first few weeks after surgery, both monitoring of anterior and posterior pituitary function and managing neurosurgical issues are the focus of care. Potential disruption of pituitary-adrenal function is covered with perioperative glucocorticoids. Various strategies exist for ensuring the integrity of this axis, but typically this is done by measuring a morning cortisol on the 2nd or 3rd postoperative days. Patients with levels <10 microg/l should continue therapy with reassessment in the later postoperative period. Monitoring for water imbalances, which are due to deficiency or excess of ADH (DI or SIADH, respectively), is accomplished by continuous accounting of fluid intake, urine output and specific gravities coupled with daily serum electrolyte measurements. DI is characterized by excess volumes of inappropriately dilute urine, which can lead to hypernatremia. Most patients maintain adequate fluid intake and euvolemia, but desmopressin therapy is required for some. SIADH, which peaks in incidence on 7th postoperative day, presents with hyponatremia that can be severe and symptomatic. Management consists of fluid restriction. Neurosurgical monitoring is primarily for disturbances in vision or neurological function, and although uncommon, for CSF leak and infections such as meningitis. In the later postoperative period, the adrenal, thyroid and gonadal axes are assessed. New persistent hypopituitarism is rare when transsphenoidal surgery is performed by an experienced surgeon. Various strategies are available for assessing each axis and for providing replacement therapy in patients with deficiencies. Long term monitoring with assessments of visual, neurological and pituitary function coupled with pituitary imaging is necessary for all patients who have undergone surgery, irrespective of the hormone status of their tumors.