[Prolactin--a hormone with many effects].
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Animals↗
Biomedical subjects
B A Bengtsson
Publications and source records attributed to B A Bengtsson.
Double-blind, placebo-controlled study of growth hormone treatment in elderly patients undergoing chronic hemodialysis: anabolic effect and functional improvement.
Elderly patients with end-stage renal disease often have protein and/or caloric malnutrition that severely affects general well-being and mortality. Uremia is associated with resistance to the action of growth hormone (GH). This resistance could be of clinical importance in elderly dialysis patients. In the present study, the effects of GH treatment were assessed in elderly patients receiving chronic hemodialysis. Twenty hemodialysis patients with a mean age of 71.7 years (range, 53 to 92 years) were included on a 6-month, randomized, double-blind, placebo-controlled trial of GH treatment. The dose of GH was 66.7 microgram/kg, administered subcutaneously three times weekly immediately after each dialysis session. Body composition was measured using total-body potassium levels, computed tomography of the lower leg, and bioelectrical impedance analysis. Serum albumin concentrations and handgrip strength were also measured. GH treatment increased the serum concentration of insulin-like growth factor-I (IGF-I), IGF-I/IGF-binding protein-3 ratio, fat-free mass, and the serum concentration of albumin compared with placebo. The number of patients with serum albumin levels less than 40 g/L was reduced by a factor of three in the GH-treated group. Handgrip strength increased in response to GH treatment compared with placebo. Six months of GH treatment in elderly hemodialysis patients produced anabolic effects, with improved muscle performance. Also, the number of patients with low albumin levels was markedly reduced, indicating improved nutritional status and/or attenuated catabolism. These are all important beneficial effects for individual patient outcomes.
Aged↗
Possible protective role of growth hormone in hypoxia-ischemia in neonatal rats.
Perinatal asphyxia still constitutes a clinical hazard associated with considerable neurologic morbidity. Several growth factors, including insulin-like growth factor-I (IGF-I), have been reported to have a neuroprotective effect in experimental models of hypoxic ischemia (HI). In the present study, we have applied solution hybridization for quantification of the time course for mRNA expression of IGF-I, IGF-I receptor, and growth hormone (GH) receptor after HI in 7-d-old rats. There was a significant increase in IGF-I mRNA in the damaged hemisphere 72 h (1.19 +/- 0.28 vs 0.48 +/- 0.02 amol/microg DNA, p < 0.05) and 14 d (0.61 +/- 0.18 vs 0.19 +/- 0.05 amol/microg DNA, p < 0.05) after HI. In the contralateral hemisphere, both IGF-I and GH receptor mRNA had increased by 14 d after the insult (0.36 +/- 0.042 vs 0.13 +/- 0.011, p < 0.05, and 0.31 +/- 0.013 vs 0.11 +/- 0.004 amol/microg DNA, p < 0.001, respectively). There were no changes in IGF-I receptor mRNA throughout the study period. We have also evaluated the neuroprotective effect of GH after HI in neonatal rats. GH administered s.c. after HI in daily doses of 50 and 100 mg/kg provided a moderate neuroprotection of 20%. These results suggest a role for the GH/IGF-I axis in the neurochemical process leading to HI brain injury.
Animals↗
Serum leptin concentration and insulin sensitivity in men with abdominal obesity.
OBJECTIVE: We have examined the association between generalized adiposity, abdominal adiposity, insulin sensitivity, and serum levels of leptin in a cross-sectional study of abdominally obese men. RESEARCH METHODS AND PROCEDURES: Thirty men, 48 to 66 years of age with a body mass index (BMI) of between 25 kg/m2 and 35 kg/m2 and a waist hip ratio of >0.95, were included in the study. Serum leptin concentration was measured using radioimmunoassay. Total body fat percentage was determined from total body potassium, abdominal adiposity was measured by computed tomography, and the glucose disposal rate (GDR) was measured during an euglycemic, hyperinsulinemic glucose clamp. RESULTS: Significant correlations were found between serum leptin concentration and BMI, percentage body fat, abdominal subcutaneous adipose tissue, serum insulin, GDR, and 24-hour urinary-free cortisol. In a multiple regression analysis, it was shown that abdominal subcutaneous adipose tissue, GDR, and BMI explained 72% of the variability of serum leptin concentration. GDR demonstrated an independent inverse correlation with serum leptin concentration. DISCUSSION: In abdominally obese men with insulin resistance, it was demonstrated that most of the individual variability in serum leptin concentration was explained by the amount of subcutaneous abdominal adipose tissue, insulin sensitivity, and BMI.
Abdomen↗
Beneficial effects of long-term GH replacement therapy on quality of life in adults with GH deficiency.
OBJECTIVE: Quality of life tends to be adversely affected in adults with GH deficiency. The aim of this study was to examine changes in quality of life in a large group of GH-deficient adults receiving long-term GH replacement therapy. DESIGN: The study was conducted in two stages. The first stage was a prospective, open trial of GH replacement therapy in 71 GH-deficient adults, during which GH was administered for 20-50 months. For the second stage, a further 90 patients were recruited to create a population of 161 GH-deficient adults, all of whom had received GH replacement therapy for more than 12 months. This population was investigated retrospectively, using a questionnaire designed specifically for this study. PATIENTS: All patients were GH deficient and showed a peak GH response of less than 3.0 micrograms/l during an insulin tolerance test in which blood glucose levels dropped to 2.2 mmol/l or below. MEASUREMENTS: The quality of life of patients in the prospective stage was assessed using the Nottingham Health Profile (NHP) parts I and II, and the Psychological General Well-Being (PGWB) index. In the retrospective study patients completed a specially developed questionnaire, designed to determine whether changes in quality of life were sudden or gradual, and whether quality of life continued to change after GH had been administered for more than 12 months. RESULTS: In the prospective stage, mean overall score on the NHP I improved significantly during the first 6 months of GH therapy, and remained at its new level thereafter. Scores in all areas of the NHP II improved significantly between baseline and 20-50 months, as did the total score and five of six area scores on the PGWB index. The total PGWB score and three area scores improved significantly between 6 or 12 months and 20-50 months. In the retrospective stage, 92.7% of the patients reported that they had experienced positive effects of GH therapy. In 30.3% of patients, however, such effects did not become apparent until GH had been administered for more than 6 months. Almost 60% of patients felt that their condition was still improving. CONCLUSIONS: These results indicate that the previously reported beneficial effects of GH therapy on quality of life in GH-deficient adults are sustained during long-term therapy. In addition, they suggest that, once started, GH therapy should be continued for at least 6 months before judgements are made regarding its efficacy in improving quality of life.
Adult↗
Altered lipid pattern explains increased cardiovascular mortality in hypopituitary patients with growth hormone deficiency.
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Adult↗
Acromegaly and Cushing's syndrome due to ectopic production of GHRH and ACTH by a thymic carcinoid tumour: in vitro responses to GHRH and GHRP-6.
A 50-year-old male presented with diabetes mellitus and Cushing's syndrome associated with a large mediastinal mass. The levels of serum cortisol were high (1500-1800 nmol/l) without diurnal variation. Plasma ACTH levels (200-250 ng/l) and urinary excretion of cortisol were also increased. The levels of these hormones did not change in response to stimulation with corticotrophin releasing hormone (CRH) or suppression with high doses of dexamethasone. The patient had an elevated baseline GH level (7.3 mU/l), and the levels of immunoreactive GH-releasing hormone (GHRH) in eight plasma samples were markedly increased (600-1500 ng/l). Circulating levels of IGF-1, chromogranin A and neuropeptide Y (NPY) were also increased. Computer-assisted tomography and octreotide scintigraphy revealed a large mediastinal tumour and metastases in the left supraclavicular fossa. During treatment with octreotide, the baseline GH level was decreased (to 4.4 mU/l), while the GH pulse height was unchanged. Surgical removal of most of the tumour tissue resulted in a further decrease in the baseline serum GH level to a value (1.6 mU/l) about 20% of that before treatment, while the pulse height and mean GH were affected to a lesser extent. Postoperatively, circulating levels of cortisol and IGF-1 decreased, and the patient exhibited clinical improvement. Histological examination showed a neuroendocrine tumour with characteristics consistent with a foregut carcinoid of thymic origin. Immunoreactive GHRH, ACTH and NPY, but not immunoreactive GH, were detected in 80-90% of the tumour cells and the three peptides appeared to be co-localized. In primary culture, cells from this tumour displayed calcium influx in response to GHRH or GH releasing peptide-6 (GHRP-6), while there were not such responses by cells from another carcinoid not producing GHRH, ACTH or NPY. These results demonstrate a rare case of ectopic production of GHRH, ACTH and NPY, and indicate that the tumour cells were responsive to GHRH and GHRP-6 as well as octreotide.
Acromegaly↗
A placebo-controlled study of growth hormone in patients with congestive heart failure.
AIM: Experimental data in heart failure models and an open trial of seven patients with idiopathic dilated cardiomyopathy have suggested beneficial effects of growth hormone on cardiac function. The aim of the present study was to evaluate growth hormone effects on cardiac function in a placebo-controlled study. METHODS: Twenty two patients with congestive heart failure of different aetiologies in NYHA II and III and an echocardiographic ejection fraction <0.45 were studied in a 3 month double-blind placebo-controlled study with growth hormone added to optimal heart failure therapy. Patients received either placebo (n=11) or recombinant human growth hormone (n=11) in an initial dose of 0.1 IU x kg(-1) week(-1) for 1 week, and thereafter 0.25 IU x kg(-1) week(-1) for the rest of the treatment period. Cardiac function was assessed by equilibrium radionuclide angiography and Doppler echocardiography. Functional capacity was evaluated by computerized bicycle exercise electrocardiography. RESULTS: Recombinant human growth hormone had no significant effect on systolic or diastolic cardiac function, exercise capacity or neuroendocrine activation. In addition, there was no overall improvement in functional class or dyspnoea grade. Insulin-like growth factor-I significantly increased demonstrating that the growth hormone had an endocrine effect. CONCLUSION: This is the first double-blind and placebo-controlled study of the administration, over 3 months, of recombinant human growth hormone in patients with congestive heart failure of different aetiologies. The treatment was safe and without serious side effects. However, no beneficial effects on cardiac function or structure could be detected.
Angiotensin-Converting Enzyme Inhibitors↗
Growth hormone and bone.
It is well known that GH is important in the regulation of longitudinal bone growth. Its role in the regulation of bone metabolism in man has not been understood until recently. Several in vivo and in vitro studies have demonstrated that GH is important in the regulation of both bone formation and bone resorption. In Figure 9 a simplified model for the cellular effects of GH in the regulation of bone remodeling is presented (Fig. 9). GH increases bone formation in two ways: via a direct interaction with GHRs on osteoblasts and via an induction of endocrine and autocrine/paracrine IGF-I. It is difficult to say how much of the GH effect is mediated by IGFs and how much is IGF-independent. GH treatment also results in increased bone resorption. It is still unknown whether osteoclasts express functional GHRs, but recent in vitro studies indicate that GH regulates osteoclast formation in bone marrow cultures. Possible modulations of the GH/IGF axis by glucocorticoids and estrogens are also included in Fig. 9. GH deficiency results in a decreased bone mass in both man and experimental animals. Long-term treatment (> 18 months) of GHD patients with GH results in an increased bone mass. GH treatment also increases bone mass and the total mechanical strength of bones in rats with a normal GH secretion. Recent clinical studies demonstrate that GH treatment of patients with normal GH secretion increases biochemical markers for both bone formation and bone resorption. Because of the short duration of GH treatment in man with normal GH secretion, the effect on bone mass is still inconclusive. Interestingly, GH treatment to GHD adults initially results in increased bone resorption with an increased number of bone-remodeling units and more newly produced unmineralized bone, resulting in an apparent low or unchanged bone mass. However, GH treatment for more than 18 months gives increased bone formation and bone mineralization of newly produced bone and a concomitant increase in bone mass as determined with DEXA. Thus, the action of GH on bone metabolism in GHD adults is 2-fold: it stimulates both bone resorption and bone formation. We therefore propose "the biphasic model" of GH action in bone remodeling (Fig. 10). According to this model, GH initially increases bone resorption with a concomitant bone loss that is followed by a phase of increased bone formation. After the moment when bone formation is stimulated more than bone resorption (transition point), bone mass is increased. However, a net gain of bone mass caused by GH may take some time as the initial decrease in bone mass must first be replaced (Fig. 10). When all clinical studies of GH treatment of GHD adults are taken into account, it appears that the "transition point" occurs after approximately 6 months and that a net increase of bone mass will be seen after 12-18 months of GH treatment. It should be emphasized that the biphasic model of GH action in bone remodeling is based on findings in GHD adults. It remains to be clarified whether or not it is valid for subjects with normal GH secretion. A treatment intended to increase the effects of GH/IGF-I axis on bone metabolism might include: 1) GH, 2) IGF, 3) other hormones/factors increasing the local IGF-I production in bone, and 4) GH-releasing factors. Other hormones/growth factors increasing local IGF may be important but are not discussed in this article. IGF-I has been shown to increase bone mass in animal models and biochemical markers in humans. However, no effect on bone mass has yet been presented in humans. Because the financial cost for GH treatment is high it has been suggested that GH-releasing factors might be used to stimulate the GH/IGF-I axis. The advantage of GH-releasing factors over GH is that some of them can be administered orally and that they may induce a more physiological GH secretion. (ABSTRACT TRUNCATED)
Animals↗
Two-month treatment of obese subjects with the oral growth hormone (GH) secretagogue MK-677 increases GH secretion, fat-free mass, and energy expenditure.
Obesity is associated with blunted GH secretion, unfavorable body composition, and increased cardiovascular mortality. The objective of this study was to investigate the effects of oral treatment with the GH secretagogue MK-677 on GH secretion and body composition in otherwise healthy obese males. The study was randomized, double blind, parallel, and placebo controlled. Twenty-four obese males, aged 18-50 yr, with body mass indexes greater than 30 kg/m2 and waist/hip ratios greater than 0.95, were treated with MK-677 25 mg (n = 12) or placebo (n = 12) daily for 8 weeks. Serum insulin-like growth factor I (IGF-I) increased approximately 40% with MK-677 treatment (P < 0.001 vs. placebo). Serum IGF-binding protein-3 was also significantly increased (P < or = 0.001 vs. placebo). GH and PRL (peak and area under the curve values) were significantly increased after the initial dose of MK-677. Significant increases, with the exception of peak PRL, persisted at 2 and 8 weeks of treatment. The increases in GH and PRL after the initial dose were significantly greater than the increase seen after multiple doses. Serum and urinary concentrations of cortisol were not increased at 2 and 8 weeks (P = NS, vs. placebo). Fat-free mass increased significantly in the MK-677 treatment group when determined with dual energy x-ray absorptiometry (P < 0.01) or using a four-compartment model (P < 0.05). Total and visceral fat were not significantly changed with active therapy. The basal metabolic rate was significantly increased at 2 weeks of MK-677 treatment (P = 0.01) but not at 8 weeks (P = 0.1). Fasting concentrations of glucose and insulin were unchanged, whereas an oral glucose tolerance test showed impairment of glucose homeostasis at 2 and 8 weeks. We conclude that 2-month treatment with MK-677 in healthy obese males caused a sustained increase in serum levels of GH, IGF-I, and IGF-binding protein-3. The effects on cortisol secretion were transient. Changes in body composition and energy expenditure were of an anabolic nature, with a sustained increase in fat-free mass and a transient increase in basal metabolic rate. Further studies are needed to evaluate whether a higher dose of MK-677 or a more prolonged treatment period can promote a reduction in body fat.
Adult↗
Growth hormone deficiency in adulthood and the effects of growth hormone replacement: a review. Growth Hormone Research Society Scientific Committee.
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Adult↗
Intense sympathetic nerve activity in adults with hypopituitarism and untreated growth hormone deficiency.
Perturbations in the sympathetic nervous system may be anticipated in adults with hypopituitarism and untreated GH deficiency, because the syndrome is associated with both peripheral and central factors known to modulate sympathetic traffic. The higher prevalence of hypertension and increased cardiovascular morbidity/mortality reported in GH-deficient patients may suggest increased activity of the sympathetic nervous system. We recorded muscle sympathetic nerve activity (MSNA) in 10 hypopituitary adults with adequate hormonal replacement therapy except GH and in 10 healthy controls matched for age, gender, and body mass index to test whether hormonal aberrations in hypopituitarism and untreated GH deficiency are associated with an increase in sympathetic nerve traffic. Blood samples for insulin-like growth factor I, free T4, and TSH were taken after an overnight fast, followed by an oral glucose tolerance test. Direct intraneural recordings of MSNA were performed with a tungsten microelectrode from the peroneal nerve. The hypopituitary subjects had markedly increased MSNA (54 +/- 4 bursts/min vs. 34 +/- 4 in controls; P < 0.002), which was not related to abdominal obesity or altered glucose metabolism. When assessed for the whole study group, MSNA was inversely correlated to serum insulin-like growth factor I (r = -0.59; P < 0.006) and TSH (r = -0.46; P < 0.04). MSNA was positively correlated to diastolic blood pressure (r = 0.80; P < 0.0005) in patients, but not in controls. The intense sympathetic discharge is suggested to be of central origin and may be an important underlying mechanism for the secondary hypertension and increased cardiovascular morbidity/mortality in this patient group.
Adult↗
Treatment with the oral growth hormone secretagogue MK-677 increases markers of bone formation and bone resorption in obese young males.
The effect of 2 months of treatment with the oral growth hormone (GH) secretagogue MK-677 on markers of bone metabolism was determined in healthy obese male subjects. This was a randomized, double-blind, parallel, placebo-controlled study. Twenty-four healthy obese males, 19-49 years of age, with body mass index > 30 kg/m2 were treated with MK-677 (25 mg/day; n = 12) or placebo (n = 12) for 8 weeks. MK-677 increased markers of bone formation; a 23% increase in the carboxy-terminal propeptide of type I procollagen levels and a 28% increase in procollagen III peptide levels were seen with as little as 2 weeks of MK-677 treatment (p < 0.01 and p = 0.001 vs. placebo, respectively) while a 15% increase in serum levels of osteocalcin was not detected until 8 weeks of treatment (p < 0.01 vs. placebo). Markers of bone resorption were induced within 2 weeks of treatment with MK-677; serum levels of the carboxy-terminal cross-linked telopeptide of type I collagen were increased 26% at 8 weeks (p = 0.001 vs. placebo), and urine hydroxyproline/creatinine and calcium/creatinine ratios at 8 weeks were increased by 23% (p < 0.05 vs. placebo) and 46% (p < 0.05 vs placebo), respectively, MK-677 increased serum insulin-like growth factor binding protein-5 (IGFBP-5) by 43-44% after 2-8 weeks of treatment (p < 0.01 vs. placebo). Serum IGFBP-4 was increased by 25% after 2 weeks of treatment (p < 0.001 vs. placebo) but no significant change from baseline was observed after 8 weeks of treatment. Plasma interleukin-6 was not significantly changed by active treatment. In conclusion, short-term treatment of healthy obese male volunteers with the GH secretagogue MK-677 increases markers of both bone resorption and formation. Large increases in serum levels of IGF-1 and IGFBP-5 and a transient increase in serum IGFBP-4 were found. Future long-term studies are needed to investigate if prolonged treatment with MK-677 increases bone mass.
Administration, Oral↗
Effects of growth hormone treatment on the leptin system and on energy expenditure in abdominally obese men.
The present study has examined the short- and long-term effects of growth hormone (GH) treatment on the leptin system and energy expenditure. Thirty male individuals with abdominal obesity were randomised to GH or placebo treatment in a 9-month, double-blind study. The dose of GH was 9.5 microg/kg, administered subcutaneously every evening. Serum leptin concentrations were measured by a human leptin RIA. Total RNA was isolated from adipose tissue biopsies and leptin mRNA levels were determined by a semi-quantitative reverse transcriptase-PCR assay. Body composition was determined by potassium-40 and the basal metabolic rate (BMR) was measured by a computerised, ventilated, open-hood system. As compared with placebo, an overall decrease in serum leptin concentrations as assessed by the area under the curve (AUC) (P < 0.05) and an increase in BMR (AUC, P < 0.05) were observed during GH treatment. The overall GH-induced changes were due to marked changes in serum leptin concentrations and BMR after 6 weeks of treatment. After 9 months of GH treatment there was a significant reduction in body fat (BF) while serum leptin concentrations and BMR did not differ from baseline values. Leptin mRNA levels did not change over the study period. We speculate that long-term GH treatment induces a new energy balance steady state with decreased BF stores. The effects of GH on the leptin system is suggested to be of importance for the maintenance of a lower BF mass.
Abdomen↗
Low growth hormone secretion in patients with fibromyalgia--a preliminary report on 10 patients and 10 controls.
OBJECTIVE: To evaluate the secretion of growth hormone in patients with fibromyalgia (FM). METHODS: Serum concentrations of growth hormone (24 h profiles), insulin-like growth factor I (IGF), and IGF binding protein-3 were determined in 10 women with FM and in 10 healthy controls. Quality of sleep was assessed by means of a visual analog scale. RESULTS: Sleep was significantly more disturbed in the patients than in controls. A significantly lower secretion of growth hormone was found in the patients in comparison with healthy controls. CONCLUSION: These results suggest that growth hormone secretion is decreased in patients with FM. Substitution therapy with low doses of growth hormone may be worth evaluating in the treatment of FM.
Adult↗
Improved nasal breathing in snorers increases nocturnal growth hormone secretion and serum concentrations of insulin-like growth factor 1 subsequently.
In snoring men improved nasal breathing during sleep has been shown to decrease snoring and morning tiredness. The aim was to evaluate whether improved nasal breathing had any effect on growth hormone (GH) secretion, the nocturnal secretion of GH being associated with deep sleep. Forty-two snoring men, mean age 45 years and mean body mass index 26 kg.m-2, slept every night during one month with the Nozovent nostril dilator. Before and at the end of the test period, we analysed serum insulin-like growth factor 1 (IGF-1), thyrotropin (TSH), free thyroxine (free T4), free 3,5,3'-triiodothyronine (free T3), cortisol and testosterone in blood sampled at 08:00 h. Fifteen of the 37 snoring men who completed the study experienced a reduction in snoring and were less tired in the morning during the test period. In this group, the mean IGF-1 concentration was significantly increased (p < 0.05) after one month. There was no significant difference in mean IGF-1 level between the snorers and a population sample. Likewise, TSH, free T4, free T3, cortisol and testosterone concentrations were within normal limits. Snorers with reduced snoring and morning tiredness due to improved nasal breathing showed an increase in morning IGF-1 concentration which can probably be explained by higher nocturnal GH secretion induced by more deep sleep.
Adult↗
Transsphenoidal adenomectomy in Cushing's disease via a lateral rhinotomy approach.
BACKGROUND: Cushing's disease may be treated by surgical pituitary adenomectomy. We present a surgical approach to the pituitary gland that increases the possibilities of a selective adenomectomy, and compare our results with those of other studies. METHODS: A retrospective study of patients with Cushing's disease undergoing transsphenoidal selective adenomectomy via a lateral rhinotomy at Sahlgrenska University Hospital from 1984-93 is presented. Thirty-one patients (26 women, five men; mean age: 44 years, range: 13-75 years) with Cushing's disease were followed for a median time of 4.5 years after operation (range: 1-10 years). Preoperative and postoperative urinary and serum cortisol, and circadian rhythm of serum cortisol were measured. We also measured serum TSH, T4, PRL, FSH, LH, and testosterone as well as urine and plasma osmolality. RESULTS: Our remission rate was 77% and the recurrence rate 3%. Hormonal insufficiency was rare. Hypothyroidism and hypogonadism were present in 3% of the patients, and diabetes insipidus occurred in 6% of the patients. CONCLUSION: Selective adenomectomy with its good opportunities for cure and improvement should be regarded as the treatment of choice for Cushing's disease. Using the lateral rhinotomy approach to the sphenoidal cavity results in good accessibility to the sella turcica and its pituitary adenomas, a low frequency of postoperative pituitary insufficiency, and a high remission rate.
Adenoma↗
Insulin-like growth factor-I in growth hormone-deficient adults: relationship to population-based normal values, body composition and insulin tolerance test.
BACKGROUND: Although an insulin tolerance test (ITT) is the most commonly used method for detecting growth hormone (GH) deficiency (GHD) in adults, measurements of serum insulin-like growth factor-I (IGF-I) may also be of value. OBJECTIVE: To validate the use of serum IGF-I concentration in the diagnosis of GHD in adults. DESIGN: A cross-sectional study. PATIENTS: One hundred and four patients, 60 men and 44 women, with known pituitary disease and verified GHD based on ITT. MEASUREMENTS: Serum IGF-I was determined by radioimmunoassay after acid-ethanol extraction. Body composition was estimated with total body potassium combined with total body water assessments. RESULTS: According to age- and sex-adjusted population-based references values, 51 patients had serum IGF-I concentrations below -2 SD of the predicted values and 53 had concentrations within 2 SD. Fifty-seven per cent of the patients aged 41 years (25th percentile) or below and 39% of the patients aged 57 years (75th percentile) or above had serum IGF-I concentrations below -2 SD. Women had lower mean IGF-I SD scores than men (P < 0.01). Serum IGF-I was correlated with peak GH response during ITT (r = 0.40; P < 0.001), age (r = -0.27; P < 0.01), duration of hypopituitarism (r = -0.52; P < 0.001), number of pituitary hormonal deficiencies (r = -0.35; P < 0.001), body cell mass (r = 0.30; P < 0.01) and serum insulin (r = 0.21; P < 0.05). The peak GH response during ITT correlated with spontaneous GH secretion, duration (P = -0.48; P < 0.001) and number of deficiencies (r = -0.50; P 0.001). CONCLUSION: The measurement of serum IGF-I concentrations is not suitable as a single diagnostic test for growth hormone deficiency in adults. Even as a screening test, its use appears to be limited, especially in elderly subjects. The serum level of IGF-I was influenced by several factors in addition to GH, such as age, gender, anthropodometry and serum insulin level. The peak GH response during the insulin tolerance test appears to be influenced to a lesser degree by these factors.
Adolescent↗