Increase in haemoglobin concentrations in growth hormone deficient adults during human recombinant growth hormone replacement therapy

OBJECTIVE

Recombinant human growth hormone is being used increasingly in the treatment of GH deficiency in adults. In addition to erythropoietin, insulin-like growth factor-I (IGF-I) has been demonstrated to stimulate hematopoiesis in animals, especially rodents. We have determined the effect of growth hormone (GH) administration on haematopoiesis.

PATIENTS AND DESIGN

Seventeen patients (10 males and 7 females; mean age 47 +/- 2 years; range 30-59) with biochemically proven adult-onset GH deficiency (GHD) were treated with human recombinant growth hormone (rhGH) as replacement therapy for more than 96 weeks in a dosage of 12.5 micrograms/kg/day (initial dosage during the first 4 weeks 6.25 micrograms/kg/day). The diagnosis of GHD had been confirmed using a standard arginine-infusion test (0.5 g/kg body weight). Blood samples were collected for safety and efficacy parameters before and during the GH treatment period.

MEASUREMENTS

Routine methods were used for the haematological and biochemical measurements. IGF-I concentrations were measured, using a commercial RIA kit.

RESULTS

From week 36 and onwards, we observed a significant increase in individual haemoglobin (Hb) concentrations, especially in the male patients. Mean Hb in the male patients before treatment amounted to 9.1 +/- 0.2 mmol/l (range 8.1-10.5) and increased by 0.93 +/- 0.2 mmol/l (P < 0.05) after 120 weeks of rhGH replacement therapy. The mean Hb concentration in female patients before treatment was 8.1 +/- 0.1 mmol/l and an increase of 0.32 +/- 0.1 mmol/l (P < 0.05) was observed after 120 weeks. For all 17 patients the mean increase in Hb after 120 weeks was 0.73 +/- 0.2 mmol/l (P < 0.05). IGF-I concentrations also increased during therapy from 86 +/- 9 pg/l to 253 +/- 26 pg/l within 24 weeks (P < 0.05). No significant changes in leucocyte or platelet counts were found.

CONCLUSIONS

Long-term replacement therapy with rhGH in patients with adult-onset GHD induces a significant increase in Hb concentrations, while serum leucocyte and platelet counts do not change.

Selective excision of adenomas originating in or extending into the pituitary stalk with preservation of pituitary function

When the surgeon identifies an adenoma within the gland and selectively excises it, endocrine-active pituitary tumors are usually cured and pituitary function is preserved. Occasionally ectopic adenomas arise primarily in the pituitary stalk or arise superiorly in the midportion of the anterior lobe and extend upward within the stalk. To determine if these tumors can be selectively excised with preservation of pituitary function, the authors examined the outcome of selective adenomectomy in 10 patients with Cushing's disease with an ectopic adenoma originating in, and confined to, the stalk (four microadenomas) or an adenoma extending superiorly through the diaphragma sella and into the stalk (five microadenomas and one macroadenoma) from an operative series of 516 patients with Cushing's disease. To reach the adenoma transsphenoidally in these patients, the diaphragma sella was incised anteroposteriorly in the midline to the anterior edge of the stalk, the suprasellar cistern was entered, and the adenoma was selectively excised using care to limit injury to the infundibulum. After selective adenomectomy, Cushing's disease remitted in all patients. All patients were hypocortisolemic immediately after surgery and required hydrocortisone for up to 21 months. Apart from the adrenal axis, pituitary function was normal in five patients in the immediate postoperative period, including two patients with tumors confined to the stalk and three patients with preoperative hypothyroidism (one patient) and/or hypogonadism (three patients). Three others with transient postoperative hypothyroidism (one patient) or diabetes insipidus (two patients) had normal pituitary function within 7 months of surgery. One patient with hypothyroidism and one with hypogonadism before surgery had panhypopituitarism postoperatively. A patient with a microadenoma located high in the stalk next to the optic chiasm had bitemporal hemianopsia postoperatively. These results demonstrate the feasibility of achieving curative transsphenoidal resection and preservation of pituitary function in cases of pituitary adenomas that are confined to the pituitary stalk or tumors that extend superiorly within the stalk from an intrasellar origin.

Insulin-like growth factor binding protein-1 levels in the diagnosis of hypoglycemia caused by hyperinsulinism

The diagnosis of hypoglycemia caused by hyperinsulinism may be difficult because insulin levels are not uniformly elevated at the time of hypoglycemia. Insulin-like growth factor binding protein-1 (IGFBP-1) is a 28 kd protein whose secretion is acutely inhibited by insulin. We hypothesized that serum levels of IGFBP-1 would be a useful marker of hyperinsulinism. We measured IGFBP-1 levels during the course of standardized fasting studies in hospitalized children; 36 patients became hypoglycemic during the fasting studies, and samples obtained at the point of hypoglycemia were analyzed. On the basis of the currently used diagnostic criteria, 13 children had hyperinsulinism, 16 had ketotic hypoglycemia or no disorder, 3 had hypopituitarism or isolated growth hormone deficiency, 2 had glycogen storage disease type 1 and 2 had fatty acid oxidation disorders. In control subjects (children with ketotic hypoglycemia or no disorder), IGFBP-1 levels rose during fasting to a mean of 343.8 +/- 71.3 ng/ml in the sample drawn at the time of hypoglycemia. Mean IGFBP-1 levels at hypoglycemia for the entire group with hyperinsulinism were 52.4 +/- 11.5 ng/ml, significantly different from levels seen in control subjects (p < 0.0001). In children with moderately controlled hyperinsulinism (fasting tolerance > 4 hours), mean IGFBP-1 levels at the time of hypoglycemia were 71.5 +/- 16.9 ng/ml. IGFBP-1 levels in the children with poorly controlled hyperinsulinism (fasting tolerance < 4 hours) failed to rise during fasting, with a mean of 30.1 +/- 10.4 ng/ml in the final sample. IGFBP-1 levels were inversely correlated with serum insulin and C-peptide levels (r = -0.71 and -0.72, respectively; p < 0.0001). Patients with other endocrinologic or metabolic diseases that result in fasting hypoglycemia demonstrated a rise in IGFBP-1 levels similar to that seen in ketotic hypoglycemia. Low serum levels of IGFBP-1 at the time of hypoglycemia provide an additional marker of insulin action that might help to differentiate hyperinsulinism from other hypoglycemic disorders.

Fasting and postprandial lipid abnormalities in hypopituitary women receiving conventional replacement therapy

Hypopituitary patients, particularly women, have excess mortality, mostly due to vascular disease. We have studied circulating lipid and lipoprotein concentrations, fasting and over 24 h, in hypopituitary women and men and in matched controls. Firstly, 67 hypopituitary patients (36 women) and 87 normal controls (54 women) were studied after an overnight fast. Secondly, 12 patients (6 women) and 14 matched controls (7 women) were studied over 24 h of normal meals and activity. The patients were all GH deficient and were replaced with cortisol, T4, and sex hormones where appropriate, but not with GH. In the first study, circulating triglycerides, total cholesterol, high density lipoprotein (HDL) cholesterol, and low density lipoprotein (LDL) cholesterol were measured after an overnight fast. In the second study, fasting levels of apolipoprotein B, apolipoprotein A1, and lipoprotein(a) were also measured, and then circulating triglyceride and total cholesterol concentrations were measured over 24 h. Fasting concentrations of triglyceride (mean +/- SEM, 1.73 +/- 0.22 vs. 1.11 +/- 0.09 mmol/L; P = 0.0025), total cholesterol (6.45 +/- 0.25 vs. 5.59 +/- 0.21 mmol/L; P = 0.002), LDL cholesterol (4.58 +/- 0.24 vs. 3.80 +/- 0.19 mmol/L; P = 0.007), and apolipoprotein B (135 +/- 10 vs. 111 +/- 9 mg/dL; P = 0.048) were elevated in hypopituitary compared to control women. The lipid alterations were observed in older and younger women and occurred independently of sex hormone or glucocorticoid replacement. Fasting values were not significantly different in hypopituitary and control men. Patients and controls (women and men) had similar fasting HDL cholesterol, apolipoprotein A1, and lipoprotein(a) concentrations. Although the differences that existed in fasting lipid values were most marked in women, the men were also abnormal in this respect, in that a higher proportion of hypopituitary than control men had total and LDL cholesterol above recommended values (> or = 6.2 and > or = 4.1 mmol/L, respectively). In the postprandial period (0730-2030 h), the areas under the curve (AUC) for circulating triglyceride and total cholesterol were significantly higher in hypopituitary than control women (P = 0.0089 and P = 0.0016, respectively). The AUC for triglyceride and total cholesterol over 24 h were also significantly increased (P = 0.009 and P = 0.0004, respectively). No significant differences were observed for postprandial and 24-h AUC for triglyceride and total cholesterol concentrations in men. We conclude that hypopituitarism with conventional replacement therapy is associated with unfavorable fasting and postprandial lipid and lipoprotein concentrations, particularly in women. The changes may contribute to the observed increased vascular morbidity and mortality.

Elevated leptin concentrations in growth hormone-deficient hypopituitary adults

BACKGROUND

Hypopituitarism with growth hormone (GH) deficiency is associated with obesity characterized by central (abdominal) distribution of fat. Recent work has demonstrated that leptin, a product of obese gene, is raised in obesity.

OBJECTIVE

To study circulating leptin levels in GH-deficient hypopituitary adults and to investigate its anthropometric, gender and metabolic relations.

METHODS

After an overnight fast of 10-12 hours, anthropometric parameters and body composition were measured and blood was collected for the measurement of circulating leptin, glucose, intact insulin, proinsulin, IGF-I, total cholesterol, triglycerides, high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol.

SUBJECTS

Fifteen (7 men) GH-deficient hypopituitary adults (maximum stimulated serum GH to provocative testing < 6 mU/l) and 21 (10 men) normal control subjects matched for age, gender and body mass index (BMI).

RESULTS

Fasting serum leptin was significantly higher in hypopituitary patients than controls (12.0 +/- 1.8 vs 8.0 +/- 1.5 micrograms/l, P = 0.04). The increase was more marked in obese (BMI > 26.0 kg/m2) patients compared with obese controls (15.3 +/- 2.0 vs 8.8 +/- 2.3 micrograms/l, P = 0.03) than in lean patients and controls. Obese control women and men had higher leptin levels than non-obese (women, 16.6 +/- 2.7 vs 8.6 +/- 0.6 micrograms/l, P = 0.03; men, 4.9 +/- 0.5 vs 2.9 +/- 0.6 micrograms/l, P = 0.035). Similar changes were observed for obese versus non-obese patients, although the changes did not reach statistical significance. Women in each group had significantly higher leptin concentrations than men (patients: 15.5 +/- 2.3 vs 7.3 +/- 1.4 micrograms/l, P = 0.009; controls: 12.6 +/- 2.4 vs 4.3 +/- 0.5 micrograms/l, P = 0.0001). These gender differences remained significant even when expressed in relation to BMI (patients: 0.57 +/- 0.09 vs 0.26 +/- 0.05 ng.m2/ml.kg, P = 0.009; controls: 0.43 +/- 0.05 vs 0.16 +/- 0.02 ng.m2/ml.kg, P = 0.0001). Serum leptin was positively associated with body mass index (P = 0.003), percentage body fat mass (P = 0.0001) and inversely related with age (P = 0.043). It demonstrated no relation with body weight, waist circumference, waist to hip ratio, fasting IGF-I, glucose, insulin, proinsulin, total cholesterol, triglycerides, HDL and LDL cholesterol in patients nor controls; 85% of variance in leptin was explained by a model including body mass index, gender, age and hypopituitarism.

CONCLUSIONS

Leptin concentrations are raised in GH-deficient hypopituitary adults to a greater extent than would be expected from the degree of obesity.

Hydrocortisone replacement therapy in children and adolescents with hypopituitarism

OBJECTIVE

Appropriate replacement doses of glucocorticoid are important to determine in primary and secondary adrenal deficiency in children, both to avoid the risks of hypoglycaemia and adrenal crisis associated with undertreatment, and to avoid growth suppression and reduced final height potential associated with steroid excess. The aim of this study was to assess how closely conventional twice daily hydrocortisone administration mimics physiological cortisol secretion in a group of ACTH-deficient children and adolescents.

PATIENTS

Fifty children and adolescents (aged 3-20 years) were studied who had had surgery +/- radiotherapy to the hypothalamopituitary region for removal of a craniopharyngioma. The patients were subdivided into two groups: group I comprised 44 patients known to be ACTH deficient (as determined by glucagon or insulin provocation tests of anterior pituitary function performed after surgery) and maintained on twice daily oral hydrocortisone replacement; group II comprised six patients known to be ACTH sufficient at their last assessment of pituitary function and not on hydrocortisone replacement. A third group of 10 boys (aged 7-13 years) who had no known endocrinopathy were used as controls (group III).

MEASUREMENTS

After intravenous cannula insertion, blood samples were taken every 2h for measurement of plasma cortisol and glucose over a period of 24h. Patients in group I continued on their usual doses of hydrocortisone, prescribed at 0800 and 1800 h.

RESULTS

The mean total daily replacement dose of hydrocortisone for patients in group I was 12.3 mg/m2/ day (range, 5.5-18.5). On the conventional twice daily dose regimen, there was a supraphysiological medium plasma cortisol level (629 nmol/l, range 185-1600; z = -3.76, P = 0.0002) 2 h after the morning dose relative to the control group, and a prolonged and unphysiological nadir from 1400-1800 h (median at 1600 h 42 nmol/l, range 13-1170; z = -3.13, P < 0.002) before the second dose of hydrocortisone was administered. Cortisol values were low, and often negligible, during the early hours of the morning (median at 0600 h 15 nmol/l, range 13-277, z = -4.87, P < 0.00001) and spontaneous hypoglycaemia was documented in one patient on a single 0800 h sample. One patient in group II was shown to be unequivocally cortisol deficient and median cortisol values for the remaining five suggested a suboptimal rise in plasma cortisol during the early hours of the morning.

CONCLUSION

Our cohort of patients provides an excellent model for the study of glucocorticoid replacement in cortisol-deficient children and adolescents and shows, as in adults, that the aim of mimicking the physiological nyctohemeral secretion of cortisol is difficult to achieve in practice and raises a number of important considerations unique to steroid substitution therapy in this age group.

Effect of growth hormone on fatty liver in panhypopituitarism

A 17 year old boy was admitted because of short stature and hepatomegaly. He was diagnosed with panhypopituitarism and fatty liver. The fatty liver improved, not with hydrocortisone or levothyroxine treatment, but with growth hormone administration. The fatty liver in this patient was attributable to a growth hormone deficient state.

Urinary growth hormone following exercise to assess growth hormone production in adults

OBJECTIVE

The insulin stress test (IST) is the most commonly used test to assess the GH reserve in children and adults. It is a time-consuming, expensive and potentially dangerous test. We investigated whether measurement of urinary growth hormone excretion following exercise would prove on reliable method to diagnose adult GH deficiency.

DESIGN

Healthy volunteers underwent a standard IST to confirm GH secretion. Using a standardized exercise protocol on a treadmill, the urinary excretion of GH was measured. Three patients confirmed as GH deficient by an IST were exercised during the same exercise protocol and their urinary excretion of GH was measured.

PATIENTS

Ten healthy volunteers and three patients with hypopituitarism were evaluated.

MEASUREMENTS

A standard IST was performed on both healthy volunteers and patients, with measurements of plasma GH and plasma cortisol. Urinary growth hormone and urinary GH/creatinine (GH/CR) ratios were measured before and after IST. On a separate visit, healthy volunteers and patients were exercised on the treadmill with measurements of plasma GH and cortisol. Urinary GH and GH/CR ratios were measured before and after exercise.

RESULTS

There was at least a two-fold increase in urinary GH and GH/CR ratios following exercise in all healthy adults. By contrast, patients with GH deficiency showed no rise in urinary GH or urinary GH/CR ratios following exercise.

CONCLUSIONS

Measurements of urinary GH following exercise can distinguish between GH-deficient adults and healthy volunteers. Urinary GH excretion can be measured over a timed interval following exercise or can be expressed as the GH/CR ratio. This can be measured on a single sample following exercise and can be used to diagnose GH deficiency. The exercise test employed for this study is arduous. We are therefore performing further studies with a less strenuous exercise protocol with a view to designing a 'patient-friendly' exercise test for GH deficiency in adults.

Glucocorticoid replacement therapy: are patients over treated and does it matter?

BACKGROUND AND OBJECTIVES

Adequate assessment of patients on glucocorticoid replacement therapy is of great importance to avoid the consequences of under or over treatment, but no simple test is available for this. The aims of this study were (1) to assess adequacy of glucocorticoid replacement in hypoadrenal patients, (2) to correlate serum cortisol levels (cortisol day curve) with 24-hour urine free cortisol excretion and (3) to assess the impact of glucocorticoid dose optimization on markers of bone formation and bone resorption.

DESIGN

Cross-sectional study of current replacement therapy and a prospective study of the effect of dose alteration on bone turnover markers.

PATIENTS

Thirty-two consecutive patients on replacement glucocorticoid therapy (12 Addison's disease, 20 hypopituitarism) from a University teaching hospital out-patient department.

MEASUREMENTS

Serum and urinary cortisol, osteocalcin, N-telopeptide of type I collagen (NTX) and bone mineral density.

RESULTS

28/32 (88%) patients required a change of therapy; 24/32 (75%) a total reduction in dose, 18/32 (56%) a change in replacement therapy regimen or drug and 14/32 (44%) both changes. The mean daily dose of hydrocortisone was reduced from 29.5 +/- 1.2 to 20.8 +/- 1.0 mg. A significant correlation was found between peak cortisol and 24-hour urine free cortisol/ creatinine (Spearman correlation r = 0.60, P < 0.0001; n = 51). Following hydrocortisone dose reduction, median osteocalcin increased from 16.7 micrograms/l (range 8.2-65.7) to 19.9 micrograms/l (8.2-56.3); P < 0.01, with no change in the NTX/creatinine ratio.

CONCLUSIONS

A high proportion of patients on conventional corticosteroid replacement therapy are over treated or on inappropriate replacement regimens. To reduce the long term risk of osteoporosis, corticosteroid replacement therapy should be individually assessed and over replacement avoided.

Abnormal carotid arterial wall dynamics in symptom-free hypopituitary adults

OBJECTIVE

Although vascular mortality is increased in hypopituitary adults on routine replacement, there are limited data on the atherosclerotic process during life in these patients. Measurement of arterial stiffness may provide an index of early vascular changes that predispose to the development of major vascular accidents.

DESIGN

Thirty-four hypopituitary adults on conventional replacement therapy and 39 age- and sex-matched controls were studied. They had no history or clinical evidence of macrovascular disease. The common carotid artery distensibility coefficient (DC), compliance coefficient (CC) and arterial stiffness index (beta index) were calculated from high-resolution ultrasonic imaging of the two common carotid arteries and from the brachial blood pressure.

RESULTS

There was no difference between patients and controls in carotid diastolic diameter (mean +/- S.E.M) (5.55 +/- 0.16 vs 5.45 +/- 0.08 mm) and pulse pressure (6.66 +/- 0.30 vs 6.58 +/- 0.24 kPa). The increase in diameter during systole was significantly lower in the hypopituitary patients (0.39 +/- 0.02 vs 0.50 +/- 0.03 mm, P < 0.001). The DC was significantly lower in patients than in controls (24.2 +/- 2.29 vs 30.1 +/- 2.01 10(-3) kPa-1, P < 0.05). The carotid CC was also significantly lower in patients than in controls (5.7 +/- 0.49 vs 7.0 +/- 0.45 10(-7) m2 kPa-1, P < 0.05). The beta index was higher in the patient group (8.4 +/- 1.3 vs 5.9 +/- 0.37, P < 0.05). When men and women were considered separately, the differences between patients and controls were statistically significant in women but not in men and were more marked in the older women subgroup.

CONCLUSIONS

Asymptomatic hypopituitary adults (especially women) on conventional replacement therapy have increased stiffness of the common carotid arteries. These findings provide additional evidence for a process leading to premature atherosclerosis in this group of patients.

Maximal secretory capacity of somatotrope cells in obesity: comparison with GH deficiency

OBJECTIVE

To evaluate the maximal secretory capacity of somatotrope cells in obesity and to compare it with that in hypopituitaric patients with GH deficiency.

DESIGN

Stimulation with GHRH. (1 microgram/kg i.v.), combined with arginine (ARG, 0.5 g/kg i.v.), which strongly potentiates the GH response to the neurohormone, likely inhibiting hypothalamic somatostatin. The reproducibility of the GH response to GHRH + ARG was evaluated in a second session.

SUBJECTS

Forty-five patients with simple obesity (OB 11 male and 34 female, age 40.5 +/- 1.8 y, BMI 38.8 +/- 1.1 kg/m2), 49 patients with hypopituitarism (GHD, 23 male and 26 female, 43.6 +/- 2.4 y, 24.7 +/- 0.7 kg/m2) and 44 normal young volunteers (NS, 25 male and 19 female, 33.8 +/- 1.0 y, 21.6 +/- 0.3 kg/m2) were studied.

MEASUREMENTS

GH levels were assayed by IRMA method, basally at -60 and 0 min, and than every 15 min up to +120 min. Basal IGF-I levels were assayed by RIA method, after acid-ethanol extraction.

RESULTS

IGF-I levels in OB were lower (P < 0.005) than those in NS but higher (P < 0.005) than those in GHD. Mean peak GH response to GHRH + ARG in OB was clearly lower than that in NS (P < 0.005) and higher (P < 0.005) than that in GHD. Sixty-percent OB and 100% GHD showed peak GH responses lower than the minimum normal limit in NS (16.5 micrograms/l) while 4% OB and only 53% GHD with GH responses lower than 3 micrograms/l, the limit under which GH replacement therapy of severe deficiency is allowed. Good intraindividual reproducibility of the GH response to GHRH + arginine test was present in all groups (OB: r = 0.78, P < 0.0001; GHD: r = 0.57, P < 0.003; NS: r = 0.74, P < 0.0001;.

CONCLUSIONS

The maximal secretory capacity of somatotrope cells is clearly less than normal in the obese but still more than is seen in GHD subjects. However, in about 50% of obese patients, the pituitary GH releasable pool overlaps with that of hypopituitaric patients with GH deficiency. Thus, even when the maximal secretory capacity of somatotrope cells is evaluated by a potent and reproducible provocative tests such as GHRH + arginine, overweight has to be taken in a great account as the cause of severely impaired GH response in patients with suspected GH deficiency.

Clinical evidence for a neuromodulator action of endothelin in the hypothalamic-pituitary-adrenal axis in man

In order to investigate whether the ubiquitous signalling peptide endothelin might also act as a neuromodulator in the stimulation of the hypothalamic-pituitary-adrenal axis, 15 patients (4 female, 11 male, aged 35-67 years) with hypopituitarism were investigated and the results were compared to those of 8 healthy male volunteers (aged 24-31 years). Patients and controls received double-blind in random order either 0.1 IE per kg body weight regular insulin (insulin induced hypoglycemia) or 1 ml 0.9% sodium chloride (placebo) on 2 separate days. Control subjects only received on an additional day 0.1 IE per kg body weight regular insulin plus glucose 10% (euglycemic hyperinsulinemic glucose clamp). In control subjects hypoglycemia resulted in a significant increase in adrenocorticotropin (ACTH) and cortisol which was preceded by an increase in circulating endothelin levels (p < 0.01 vs placebo and euglycemic clamp) while endothelin, ACTH and cortisol remained unchanged both after placebo and in the euglycemic hyperinsulinemic clamp. In contrast, patients with hypopituitarism showed neither changes in circulating endothelin levels nor a stimulation of the hypothalamic-pituitary-adrenal axis during insulin-induced hypoglycemia. These data demonstrate that 1) endothelin levels are enhanced by metabolic stress 2) the responsiveness of endothelin levels to metabolic stress is linked to the presence of an intact pituitary gland and 3) endothelin might be involved in the stimulation of the hypothalamic-pituitary-adrenal axis.

Low-dose growth hormone replacement lowers plasma leptin and fat stores without affecting body mass index in adults with growth hormone deficiency

OBJECTIVE

The ob gene product, leptin, is considered to be a marker of adipose tissue mass and a possible homeostatic regulator of body mass. Our objective was to examine the effect of GH replacement on adipose tissue stores and leptin in adult hypopituitarism.

SUBJECTS

Twenty adults, mean age 47 years (range 20-69) with proven GH deficiency were randomly allocated to either GH (up to 0.25 U/kg/week in daily doses) or placebo for 3 months before cross-over to the opposite treatment.

MEASUREMENTS

Body composition was measured by dual-energy X-ray absorptiometry (DEXA) in the whole body, trunk and limbs. Plasma leptin was measured by radioimmunoassay at baseline and +2, +4, +8 and +12 weeks in each treatment arm.

RESULTS

Total body tissue fat (mean +/- SE) was 30.1 +/- 2.2% after GH compared with 31.9 +/- 2.2% after placebo, P < 0.001 (ANOVA). There were no significant changes in BMI (kg/m2), 29.1 +/- 1.3 after placebo vs 28.8 +/- 1.2 after GH; or waist to hip ratio (WHR), 0.91 +/- 0.01 after both placebo and GH. Baseline plasma leptin showed a significant correlation with baseline BMI, r = 0.67, P < 0.005 and baseline percentage total body fat, R = 0.89, P < 0.001. Plasma leptin (adjusted by using baseline percentage total body fat as a covariate) showed a significant linear decrease with time on GH compared with placebo (P = 0.03, ANOVA).

CONCLUSIONS

Plasma leptin and total body fat fall promptly in response to low-dose replacement of GH in GH-deficient subjects. Hormone-induced changes in leptin can occur in humans in the absence of change in body mass index.

Reproducibility of the growth hormone response to stimulation with growth hormone-releasing hormone plus arginine during lifespan

The reliability and reproducibility of provocative stimuli of growth hormone (GH) secretion in the diagnosis of GH deficiency are still controversial both in childhood and in adulthood. The combined administration of GH-releasing hormone (GHRH) and arginine (ARG), which likely acts via inhibition of hypothalamic somatostatin release, is one of the most potent stimuli known so far and has been proposed recently as the best test to explore the maximal somatotrope capacity of somatotrope cells. However, it is well known that, usually, provocative stimuli of GH secretion suffer from poor reproducibility and that of the GHRH + ARG test has still to be verified. We aimed to verify the between- and within-subject variability of the GH response to the GHRH + ARG test in normal subjects during their lifespan as well as in hypopituitaric patients with GH deficiency (GHD). In 10 normal children (C: six male and four female, age 12.3 +/- 0.9 years, body mass index (BMI) = 16.6 +/- 0.7 kg/m2, pubertal stages I-III), 18 normal young adults (Y: ten male and eight female, age 31.1 +/- 1.3 years, BMI = 21.4 +/- 0.4 kg/m2), 12 normal elderly subjects (E: two male and ten female, age 74.4 +/- 1.8 years, BMI= 22.6 +/- 0.6 kg/m2) and 15 panhypopituitaric GH-deficient patients (GHD: nine male and six female, age 40.9 +/- 4.1 years, BMI= 22.7 +/- 1.0 kg/m2), we studied the inter- and intra-individual variability of the GH response to GHRH (1 microg/kg i.v.) + ARG (0.5 g/kg i.v.) in two different sessions at least 3 days apart. The GH responses to GHRH + ARG in C (1st vs 2nd session: 61.6 +/- 8.1 vs 66.5 +/- 9.4 microg/l), Y (70.4 +/- 10.1 vs 76.2 10.7 microg/l) and E (57.9 14.8 vs 52.1 +/- 8.0 microg/l) were similar and reproducible in all groups. The somatotrope responsiveness to GHRH + ARG also showed a limited within-subject variability (r = 0.71, 0.90 and 0.89 and p < 0.02, 0.0005 and 0.0005 for C, Y and E, respectively). Similarly in GHD, the GH response to the GHRH + ARG test showed a good inter- (1st vs 2nd session: 2.3 +/- 0.5 vs 2.2 +/- 0.6 microg/l) and intra-individual reproducibility (r = 0.70, p < 0.005). The GHRH + ARG-induced GH responses in GHD were markedly lower (p < 0.0005) than those in age-matched controls and no overlap was found between GH peak responses in GHD and normal subjects. In normal subjects, the GH response to GHRH + ARG is very marked, independent of age and shows limited inter- and intra-individual variability. The GH response to the GHRH + ARG test is strikingly reduced in panhypopituitaric patients with GHD, in whom the low somatotrope responsiveness is reproducible. Thus, these findings strengthen the hypothesis that GHRH + ARG should be considered the most reliable test to evaluate the maximal secretory capacity of somatotrope cells and to distinguish normal subjects from GHD patients in adulthood.

Hypothalamic-hypophyseal dysgenesis as a neuroimaging correlate of pituitary hormone deficiency in anophthalmia

PURPOSE

To document the association of neurohypophyseal dysgenesis with hypopituitarism in a child with primary bilateral anophthalmia.

METHODS

An infant with bilateral anophthalmia underwent magnetic resonance imaging and endocrinologic evaluation.

RESULTS

Magnetic resonance imaging showed dysgenesis confined to the hypothalamus and hypophyseal stalk. Endocrinologic testing showed low serum cortisol and pituitary gonadotropin levels.

CONCLUSION

Magnetic resonance imaging can help predict which children with anophthalmia will have endocrinologic deficiencies.

Growth hormone response to growth hormone-releasing hormone varies with the hypothalamic-pituitary abnormalities

We determined growth hormone (GH) and insulin-like growth factor I (IGF-I) levels after a 3 h infusion of escalating doses of growth hormone-releasing hormone (GHRH(1-29)) followed by a bolus injection in hypopituitary patients with marked differences in pituitary features at magnetic resonance imaging (MRI) in order to evaluate further the contribution of MRI in the definition of pituitary GH reserve in GH-deficient patients. Twenty-nine patients (mean age 14.5 +/- 4.0 years) were studied. Group I comprised 13 patients: seven with isolated GH deficiency (IGHD) (group Ia) and six with multiple pituitary hormone deficiency (MPHD) (group Ib) who had anterior pituitary hypoplasia, unidentified pituitary stalk and ectopic posterior pituitary at MRI, Group II consisted of eight patients with IGHD and small anterior pituitary/empty sella, while in group III eight had IGHD and normal morphology of the pituitary gland. Growth hormone and IGF-I levels were measured during saline infusion at 08.30-09.00 h, as well as after infusion of GHRH (1-29) at escalating doses for 3h: 0.2 micrograms/kg at 09.00-10.00 h, 0.4 micrograms/kg at 10.00-11.00 h, 0.6 micrograms/kg at 11.00-12.00 h and an intravenous bolus of 2 micrograms/ kg at 12.00 h. In the group I patients, the peak GH response to GHRH(1-29) was delayed (135-180 min) and extremely low (median 2mU/l). In group II it was delayed (135-180 min), high (median 34.8 mU/l) and persistent (median 37.4 mU/l at 185-210 min). In group III the peak response was high (median 30.8 mU/l) and relatively early (75-120 min) but it declined rapidly (median 14.4 mU/l at 185-210 min). In one group I patient, GH response increased to 34.6 mU/l. The mean basal value of IGF-I levels was significantly lower in group I (0.23 +/- 0.05 U/ml) than in groups II (0.39 +/- 0.13U/ ml, p < 0.01) and III (1.54 +/- 0.46 U/ml, p < 0.001) and did not vary significantly during the GHRH(1-29) infusion. The present study demonstrates that the impaired GH response to 3 h of continuous infusion of escalating doses of GHRH(1-29) was strikingly indicative for pituitary stalk abnormality, strengthening the case for use of GHRH in the differential diagnosis of GH deficiency. The low GH response, more severe in MPHD patients, might be dependent on the residual somatotrope cells, while the better response (34.6 mU/l) in the group Ia patients might suggest that prolonged GHRH infusion could help in evaluating the amount of residual GH pituitary tissue. Pituitary GH reserve, given the GH response to GHRH infusion in GH-deficient patients with small anterior pituitary/empty sella, seems to be maintained.

Overnight metabolic fuel deficiency in patients treated conventionally for hypopituitarism

BACKGROUND

Hormone replacement in hypopituitary adults attempts to reproduce normal physiology. Conventional regimens fail to mimic normal hormone profiles over 24 hours.

OBJECTIVE

To investigate the metabolic consequences of conventional hormone replacement in hypopituitary adults by measuring circulating levels of the major fuels, glucose, non-esterified fatty acids (NEFA), glycerol and 3-hydroxybutyrate (3-OHB) over 24 hours in hypopituitary subjects and controls.

SUBJECTS

Ten GH and adrenocorticotrophin deficient hypopituitary adults on conventional replacement and 13 controls matched for age, sex and body mass index were studied. The patients received replacement with hydrocortisone twice daily (at 0730 and 1730 h; mean (range) daily dose 22 (10-30) mg/24 h) but not with GH. Other hormones were replaced as clinically necessary.

MEASUREMENTS

Circulating glucose, NEFA, glycerol and 3-OHB levels were measured over 24 hours together with concentrations of cortisol (total and free), GH and insulin, and urinary free cortisol.

RESULTS

Levels of glucose, NEFA and 3-OHB were lower in patients than controls (mean +/- SEM) (4.3 +/- 0.1 vs 5.3 +/- 0.1 mmol/l, P = 0.0001; 291 +/- 46 vs 448 +/- 48 mumol/l, P = 0.015; 78 +/- 8 vs 136 +/- 24 mumol/l, P = 0.035, respectively) before breakfast. This decrease in glucose, NEFA and 3-OHB was observed in the patient group throughout the night, from midnight to breakfast. For NEFA, the decrease persisted throughout the 24 hours. Glycerol did not differ significantly in patients and controls. Integrated levels of total and free plasma cortisol, and 24-hour urine cortisol excretion, were normal in patients but total and free plasma cortisol concentrations overnight were markedly decreased (overnight area under the curve (AUC) of total cortisol: 440 +/- 154 vs 1593 +/- 267 nmol/l h, P = 0.0024; overnight AUC of free cortisol: 24 +/- 8 vs 161 +/- 26 nmol/l h, P = 0.0001). GH levels were low throughout the whole 24 hours in the patient group (24-hour AUC: 10.6 +/- 5.1 vs 74.6 +/- 19.6 mU/l h, P = 0.008).

CONCLUSIONS

Hypopituitary adults on conventional hormone replacement regimens have low concentrations of metabolic fuels, glucose, non-esterified fatty acids and 3-hydroxybutyrate throughout the night, possibly related to GH deficiency or to decreased overnight circulating cortisol levels. This overnight fuel deficiency may underlie the mechanism for the non-specific symptoms, such as fatigue and headache in the early morning, which are frequent in this group of patients.

Delayed onset of diuresis in a patient with acute renal failure due to hemorrhagic fever with renal syndrome who also developed anterior hypopituitarism

A 23-year-old man developed acute renal failure (ARF) due to hemorrhagic fever with renal syndrome (HFRS). The patient also developed anterior hypopituitarism as a complication of HFRS. The patient's oliguric phase was very much prolonged for over 10 days before the diuresis began. The urine output during the oliguric phase was near anuric (< 50 ml/day). Interestingly, the patient began to diurese just after the institution of glucocorticoid and thyroid hormone replacement therapy. The plasma atrial natriuretic polypeptide went up to a smaller peak (150.0 pg/ml) at the onset of diuresis compared with 15 other patients (292.4 +/- 190.4 pg/ml) who did not develop anterior hypopituitarism. The delayed onset of diuresis and smaller increase of plasma ANP may have a causal relationship with the patient's hypopituitarism.

Growth hormone treatment in hypopituitary GH deficient adults reduces circulating cortisol levels during hydrocortisone replacement therapy

OBJECTIVES

Patients with GH deficiency frequently have multiple hormone deficiencies and require hydrocortisone replacement. We have investigated whether GH treatment alters circulating cortisol levels in hypopituitary patients receiving stable replacement therapy.

DESIGN

Subjects were studied during 6 or 12 months of s.c. GH at a dose of 0.25 IU/kg/week (0.125 IU/kg/week for the first 4 weeks), and after a wash-out period of at least 2 months off GH (range 2-5 months).

PATIENTS

Fourteen hypopituitary patients (2F:12M) receiving stable hydrocortisone replacement and thyroxine, gonadal steroids and bromocriptine therapy as required.

MEASUREMENTS

Serum cortisol values were measured throughout the day over 10.5 hours. Thyroid hormones and cortisol binding globulin (CBG) were measured in the baseline sample. Comparisons of the serum cortisol peak after receiving the first dose of hydrocortisone, the time when the serum cortisol peak was obtained, the area under the curve (AUC) for the cortisol values and the levels of unbound cortisol on and off GH therapy were made. The results are expressed as mean +/- SEM. Comparisons were carried out within individuals, using the Wilcoxon signed rank test. A P-value less than 0.05 was considered statistically significant.

RESULTS

During GH therapy, there was a significant reduction in the mean cortisol peak (662.2 +/- 61.1 vs 848.0 +/- 58.6 nmol/l; P = 0.001), and in the AUC for cortisol (185.3 +/- 18.3 vs 230 +/- 17.9 nmol/l/10.5h; P = 0.03), but there was no significant change in the time of the cortisol peak (55.7 +/- 7.6 vs 57.8 +/- 4.9 minutes; P = NS). During GH therapy there was a significant reduction in CBG levels (33.64 +/- 1.16 vs 40.86 +/- 1.34 mg/l; P = 0.001); however, no changes were found in the levels of calculated unbound cortisol on and off GH (2.87 +/- 0.38 vs 2.90 +/- 0.30 nmol/l; P = NS). During GH therapy, there was a significant increase in serum triiodothyronine (T3) (1.88 +/- 0.15 vs 1.44 +/- 0.11 nmol/l; P = 0.01), and a significant decrease in thyroxine (T4) levels (74.9 +/- 11.1 vs 97.6 +/- 10.9 nmol/l; P = 0.02) but levels remained within the normal range. No change was observed in serum TSH levels (0.29 +/- 0.13 vs 0.83 +/- 0.71 mU/l; P = NS).

CONCLUSIONS

These results suggest that GH therapy in GH deficient adults produces an alteration in the measured serum cortisol profile, with a reduction in concentration of total cortisol in blood after orally administered hydrocortisone. These changes in circulating cortisol probably depend primarily on the fall in CBG levels, as no changes were found in the levels of calculated unbound cortisol on and off GH. Our data show that when measuring circulating cortisol levels, the results should be interpreted with caution in GH deficient patients on GH replacement, and different criteria may have to be applied to the circulating cortisol profile of these patients. The results highlight the importance of ensuring adequate corticosteroid replacement in patients starting GH therapy.

Low density lipoprotein particle size in hypopituitary adults receiving conventional hormone replacement therapy

Adults receiving conventional replacement therapy for hypopituitarism are known to have increased cardiovascular mortality. The aim of this study was to assess the lipid profiles of 30 hypopituitary adults compared with 2 case control groups, 1 matched for age, sex, and body mass index (BMI) and the second matched for age and sex only with a BMI representative of the general population. Fasting lipids, lipoproteins, and apoproteins (Apo) were determined by routine methods. Low density lipoprotein (LDL) particle size was determined by nondenaturing gradient gel electrophoresis. LDL size was significantly smaller in the hypopituitary group (25.9 +/- 0.1 nm) than in the BMI-matched (26.2 +/- 0.1 nm; P < 0.05) and standard control (26.3 +/- 0.1 nm; P < 0.01) groups. High density lipoprotein cholesterol levels in the hypopituitary group were significantly lower than those in the BMI-matched control group (1.13 +/- 0.06 vs. 1.34 +/- 0.06 mmol/L; P < 0.05) and the standard control group (1.38 +/- 0.06 mmol/L; P < 0.005). Apo A1 levels were also lower compared with those in the BMI-matched (122 +/- 6 vs. 137 +/- 4 mg/dL; P < 0.05) and the standard (143 +/- 4 mg/dL; P < 0.005) control groups. There was a trend toward higher triglyceride levels when the hypopituitary subjects were compared with the standard control group [1.4 (95% CI, 1.3-2.2) vs. 1.0 (95% CI, 0.9-1.4) mmol/L; P = 0.06]. These differences were more marked in the female subjects studied. No significant differences were noted in total cholesterol, LDL cholesterol, or Apo B levels. We conclude that hypopituitary patients receiving conventional replacement therapy have an atherogenic lipid profile characterized by small dense LDL, decreased high density lipoprotein cholesterol, and increased triglyceride levels, which may contribute to the excess cardiovascular mortality in this group.

47 XXY/46 XY mosaic Klinefelter's syndrome presenting with multiple endocrine abnormalities

We report here a rare case of 47 XXY/46 XY mosaic Klinefelter's syndrome associated with multiple endocrine disorders. A 35-year-old male admitted for the evaluation of renal dysfunction and recurrent bone fractures was diagnosed as having Klinefelter's syndrome by endocrinological examinations and sex chromosome analysis. He has suffered from diabetes mellitus for more than ten years. The serum FSH and LH levels were high together with low free testosterone and estradiol levels. There was a discrepancy between basal serum GH and somatomedin-C levels. On admission, thyroid function revealed thyrotoxicosis with low radioactive iodine uptake and negative thyroid autoantibodies. During hospitalization, serum FT3 and FT4 levels were gradually decreased and serum TSH levels became elevated, leading to the diagnosis of subacute thyroiditis. Serum ACTH levels showed high basal levels with delayed, exaggerated responses to insulin-induced hypoglycemia. Rapid ACTH test (1-24ACTH 0.25 mg) showed low cortisol responses and many of the adrenocortical steroids in plasma and urine were low or low normal. Furthermore, bone mineral density (BMD) by DEXA showed marked osteoporosis. Possible mechanisms underlying these varied endocrine disorders remain to be elucidated.

Endocrine disorders in septo-optic dysplasia (De Morsier syndrome)--evaluation and follow up of 18 patients

Septo-optic dysplasia (SOD) is characterized by hypoplasia of the optic nerve, various types of forebrain defects and hormonal deficiencies. We have studied the clinical and endocrinological characteristics of 18 such patients retrospectively to: (1) better define the endocrine abnormalities in children with SOD; and (2) to find approaches for the interdisciplinary long-term care of children with SOD. The children were seen at the Children's Hospital of the University of Munich from 1976 to 1992 (8 boys, 10 girls; age at initial presentation: 1 day-13 years of age, mean 1.9 years). Unilateral hypoplasia of the optic nerve was found in 7 cases, bilateral hypoplasia in 11. Sonographic, CCT or MRI yielded the following results: 4 of the patients had a cavum septum pellucidum, 3 patients had hypoplasia of the cerebellum, 1 aplasia of the corpus callosum and 1 aplasia of the fornix. An empty sella with or without an ectopic pituitary was seen in 4 cases. Height standard deviation score (SDS) at time of diagnosis was -4.0 to +0.4, mean -2.92. Endocrine deficiencies were present in all 11 patients who had undergone endocrinological investigations. Seven patients suffered from isolated growth hormone (GH) deficiency or multiple hypopituitarism. One had diabetes insipidus centralis, 2 had hypogonadotropic hypogonadism, 1 had hypothyroidism and 2 adrenal insufficiency. Hypothalamic testing was performed only in a subset of patients: in 5 of 11 children tested a thyrotropin releasing hormone (TRH test), in two out of nine a gonadotropin releasing hormone (GnRH) test, and in three out of six GH releasing hormone (GHRH) test yielded abnormal results. High prolactin levels were measured in two out of five patients.

CONCLUSION

SOD is characterized by optic nerve hypoplasia and a variety of endocrine deficiencies. In addition, forebrain malformations are present in most SOD patients. Hormonal disorders are present in some SOD patients which may be of hypothalamic origin and need to be investigated systematically.

Effect of testosterone replacement therapy on lipids and lipoproteins in hypogonadal and elderly men

We investigated the effects of long-term testosterone replacement in hypogonadal and elderly men on lipids and lipoproteins. Twenty-two men with initial serum testosterone concentrations below 3.5 ng/ml took part in the study: 11 with hypopituitarism (1st group) and 11 otherwise healthy elderly men with low testosterone levels (2nd group). Testosterone deficiency was replaced by intramuscular injections of testosterone enanthate 200 mg every second week. Plasma levels of sex hormones, gonadotropins, SHBG, lipids and lipoproteins were determined before the treatment and after 3, 6 and 12 months of treatment. During the treatment serum testosterone and estradiol increased significantly, reaching normal levels. This was associated with a decrease in total cholesterol (from 225 +/- 16.9 mg/dl to 202 +/- 13.6 mg/dl after 6 months and 198 +/- 12.8 mg/dl after 1 year of testosterone administration, P < 0.0001 in men with hypoandrogenism associated with aging and from 255 +/- 12.1 mg/dl to 214 +/- 10.6 mg/dl after 6 months and 206 +/- 9 mg/dl after 1 year of treatment, P < 0.0001 in men with hypopituitarism) and LDL-cholesterol concentrations (from 139 +/- 12.5 mg/dl to 126 +/- 10.7 mg/dl after 6 months and 118 +/- 9.8 mg/dl after 1 year of testosterone administration, P < 0.0001 in men with hypoandrogenism associated with aging and from 178 +/- 10.3 mg/dl to 149 +/- 10.2 mg/dl after 6 months and 140 +/- 7.3 mg/dl after 1 year of treatment, P < 0.001 in men with hypopituitarism). However, no significant decrease in HDL-cholesterol levels or HDL2- and HDL3-cholesterol subfractions was observed. The effects of testosterone replacement therapy on lipids and lipoproteins were similar in both groups with different aetiology of hypogonadism. No side effects on the prostate were observed. The results of this study indicate that testosterone replacement therapy in hypogonadal and elderly men may have a beneficial effect on lipid metabolism through decreasing total cholesterol and atherogenic fraction of LDL-cholesterol without significant alterations in HDL-cholesterol levels or its subfractions HDL2-C and HDL3-C.

New approach to the diagnosis of growth hormone deficiency in adults

Pyridostigmine (PD), a muscarinic cholinergic agonist, and arginine (ARG) clearly increase the growth hormone (GH) response to growth hormone-releasing hormone (GHRH) in man. The current study was undertaken to investigate the value and safety of PD + GHRH and ARG + GHRH tests as well as the measurement of serum insulin-like growth factor I (IGF-I) in diagnosing GH deficiency in adults. Fifty-four patients considered GH deficient from extensive organic or idiopathic pituitary disease and 326 healthy adults were studied. The IGF-I concentrations were lower than the 3rd percentile of normal values in only 31 of the 54 (57.4%) patients with hypopituitarism. However, the IGF-I levels in hypopituitary patients and in normal subjects overlapped more frequently between 41 and 60 years (50%) and between 61 and 80 years (92.3%) as opposed to between 20 and 40 years (8.6%). In contrast to the IGF-I measurement, the ranges of peak GH responses to PD + GHRH and ARG + GHRH tests were clearly differentiated between the hypopituitary (0.2-6.8 and 0.1-9.5 microg/l, respectively) and normal (17.7-114 and 16.1-119 microg/l, respectively). However, the PD + GHRH test was reliable only in subjects of 20-40 years of age. In conclusion, IGF-I measurement had no value in the diagnosis of GH deficiency in adults aged over 40 years, but is reliable enough when young adults of 20-40 years of age are considered. Both PD + GHRH and ARG + GHRH testing should be considered more reliable biochemical measurements of GH deficiency. In contrast to the PD + GHRH test, the ARG + GHRH test is reliable throughout the adult lifespan and appears to be the most appropriate for patient compliance and safety.