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Context: Recombinant human-GH (r-hGH), in supraphysiological doses, is self-administered by athletes in the belief that it is performance enhancing., Objective: The objective of this study was to determine whether r-hGH alters whole-body glucose and glycerol metabolism in endurance-trained athletes at rest and during and after exercise., Design: This was a 4-wk double-blind placebo-controlled trial., Setting: This study was conducted at St. Thomas Hospital (London, UK)., Participants: Twelve endurance-trained male athletes were recruited and randomized to r-hGH (0.2 U/kg.d) (n = 6) or identical placebo (n = 6) for 4 wk. One (placebo group) withdrew after randomization., Intervention: Intervention was conducted by randomization to r-hGH (0.2 U/kg x d) or identical placebo for 4 wk., Main Outcome Measures: Whole-body rates of appearance (Ra) of glucose and glycerol (an index of lipolysis) and rate of disappearance of glucose were measured using infusions of d-[6-6-2H2]glucose and 2H5-glycerol., Results: Plasma levels of glycerol and free fatty acids and glycerol Ra at rest and during and after exercise increased during r-hGH treatment (P < 0.05 vs. placebo). Glucose Ra and glucose rate of disappearance were greater after exercise during r-hGH treatment (P < 0.05 vs. placebo). Resting energy expenditure and fat oxidation were greater under resting conditions during r-hGH treatment (P < 0.05 vs. placebo)., Conclusions: r-hGH in endurance-trained athletes increased lipolysis and fatty acid availability at rest and during and after exercise. r-hGH increased glucose production and uptake rates after exercise. The relevance of these effects for athletic performance is not known.

GH replacement therapy has been shown to improve the dyslipidemic condition in a substantial proportion of patients with adult GH deficiency. The mechanisms are not yet fully elucidated. Low-density lipoprotein (LDL) apolipoprotein B100 (apoB) formation and catabolism are important determinants of plasma cholesterol concentrations. This study examined the effect of GH replacement therapy on LDL apoB metabolism using a stable isotope turnover technique. LDL apoB kinetics was determined in 13 adult patients with GH deficiency before and after 3 months GH/placebo treatment in a randomized, double-blind, placebo-controlled study. LDL apoB (13)C-leucine enrichment was determined by isotope-ratio mass spectrometry. Plasma volume was assessed by standardized radionuclide dilution technique. GH replacement therapy significantly decreased LDL cholesterol, LDL apoB concentrations, and LDL apoB pool size compared with placebo. Compared with baseline, GH replacement therapy resulted in a significant increase in plasma volume and fractional catabolic rate, whereas LDL formation rate remained unchanged. LDL lipid content did not significantly change after GH and placebo. This study suggests that short-term GH replacement therapy decreases the LDL apoB pool by increasing removal of LDL particles without changing LDL composition or LDL apoB production rate. In addition, it is possible that the beneficial effects of GH on the cardiovascular system contribute to these findings.

Protein loss leading to reduced lean body mass is recognized to contribute to the high levels of morbidity and mortality seen in critical illness. This prospective, randomized, controlled study compared the effects of conventional parenteral nutrition (TPN), glutamine-supplemented (0.4 g.kg-1.day-1) TPN (TPNGLN), and TPNGLN with combined growth hormone (GH, 0.2 IU.kg-1.day-1) and IGF-I (160 microg.kg-1.day-1) on protein metabolism in critical illness. Nineteen mechanically ventilated subjects [64 +/- 3 yr, body mass index (BMI) 23.8 +/- 1.3, kg/m2] were initially studied in the fasting state (study 1) and subsequently after 3 days of nutritional with/without hormonal support (study 2). All had recently been admitted to the ICU and the majority were postemergency abdominal surgery (APACHE II 17.5 +/- 1.0). Protein metabolism was assessed using a primed constant infusion of [1-13C]leucine. Conventional TPN contained mixed amino acids, Intralipid, and 50% dextrose. TPNGLN, unlike TPN alone, resulted in an increase in plasma glutamine concentration ( approximately 50%, P < 0.05). Both TPN and TPNGLN decreased the rate of protein breakdown (TPN 15%, P < 0.002; TPNGLN 16%, P < 0.05), but during these treatments the patients remained in a net negative protein balance. Combined treatment with TPNGLN + GH/IGF-I increased plasma IGF-I levels (10.3 +/- 0.8 vs. 48.1 +/- 9.1 nmol/l, study 1 vs. study 2, P < 0.05), and in contrast to therapy with nutrition alone, resulted in net protein gain (-0.75 +/- 0.14 vs. 0.33 +/- 0.12 g protein.kg-1.day-1, study 1 vs. study 2, P < 0.05). Therapy with GH/IGF-I + TPNGLN, unlike nutrition alone, resulted in net positive protein balance in a group of critically ill patients.

Objective: To evaluate the psychometric properties of two health status measures for adults with growth hormone deficiency (GHD): Nottingham Health Profile (NHP) and Short-Form Health Survey (SF-36)., Design: (1) A cross-sectional survey of adults with treated or untreated GHD to assess reliability and validity of the questionnaires. (2) A randomized, placebo-controlled study of 3 months' GH withdrawal from GH-treated adults to assess the sensitivity of the questionnaires to change., Patients: (1) A cross-sectional survey of 157 patients with severe GHD (peak GH < 10 mU/l on provocative testing), mean age 48.9 years (range 23-70 years), who had either received GH replacement therapy for at least 6 months immediately prior to the study or had not received GH treatment in the previous 6 months. (2) GH treatment was withdrawn from 12 of 21 GH-treated adults, all with severe GHD (peak GH < 7.7 mU/l on provocative testing), mean age 44.9 years (range 25-68 years)., Measurements: The NHP and SF-36 were used once in the cross-sectional survey, but twice in the GH-withdrawal study, at baseline and end-point (after 3 months)., Results: (1) Cross-sectional survey. Both questionnaires had high internal consistency reliability with subscale Cronbach's alphas of > 0.73 (NHP) and > 0.78 (SF-36). Calculation of an NHP Total Score, occasionally reported in the literature, was shown to be inadvisable. Overall, patients with GHD were found to have significantly worse perceived functioning than the UK general population in SF-36 subscales of General Health, Bodily Pain, Social Functioning, Physical Functioning, Role-Emotional, Role-Physical, and Vitality. Although neither questionnaire found significant differences between GH-treated and non-GH-treated patients, there were correlations with duration of GH treatment (P < 0.01) for GH-treated patients in SF-36 Mental Health (r = 0.29, N = 87) and SF-36 Vitality (r = 0.33, N = 88), indicating improvement with increasing treatment duration. The SF-36 was also more sensitive than the NHP to sex differences: men had significantly better health status compared with women (P < 0.05) in all SF-36 subscales but Mental Health, but only in one NHP subscale (Physical Mobility). (2) GH-withdrawal study. Significant between-group differences in change were found in SF-36 General Health [t(17) = 2.76, P = 0.013, two-tailed] and SF-36 Mental Health [t(17) = 2.41, P = 0.027, two-tailed]: patients withdrawn from GH reported reduced general health and mental health at end-point. The NHP found no significant change., Conclusions: The SF-36 is a better measure than the NHP of health status of people with GH deficiency because of its greater discriminatory power, with ability to detect lesser degrees of disability. It also has superior sensitivity to some subgroup differences and superior sensitivity to change compared with the NHP. The SF-36 is highly acceptable to respondents, and has very good internal consistency reliability. The SF-36 is recommended to measure the health status of adults with GH deficiency.

Objectives: Specific problems in patients with insulin-dependent diabetes mellitus (IDDM) and GH deficiency are hypoglycaemic attacks, increased insulin sensitivity and loss of energy. These problems may be related to GH deficiency., Patients: GH replacement was initiated in five patients with type 1 diabetes mellitus and GH deficiency for 6 months [four males and one female, mean age 41.6 +/- 3.8 years, mean +/- standard error of the mean (SEM); body mass index (BMI) 22.3 +/- 1.2 kg/m2]., Methods: Body composition (bioimpedance), metabolic control [haemoglobin A1C (HbA1C)], insulin requirement and frequency of hypoglycaemia were measured, and quality of life was assessed using validated questionnaires. Monthly eye photographs were taken., Results: IGF-I concentrations were below the age-adjusted range at baseline and increased significantly following GH replacement therapy [analysis of variance (ANOVA), P < 0.05]. Diabetes control as assessed by HbA1C remained stable (8.2 +/- 0.2 vs. 8.0 +/- 0.4), but needed a 1.75-fold increase in insulin dose/day. Lean body mass tended to increase (P = 0.07) and body fat mass decreased significantly (P > 0.01). Number of severe hypoglycaemic (< 3 mmol/l) attacks decreased significantly (P < 0.04) and quality of life assessed by validated questionnaires improved significantly in all patients [Psychological and General Well-Being Schedule (PGWBS), P < 0.04; Nottingham Health Profile (NHP), P < 0.05]. Monthly eye photographs revealed no changes in the retina in any patients., Conclusion: GH replacement therapy has a beneficial effect at the dose used. It restores body composition and decreases frequency and severity of hypoglycaemic episodes, thus improving quality of life. Long-term trials are needed to determine the safety of GH replacement therapy in these patients.

Objectives: Patients with adult GH-deficiency are thought to have an increased risk of cardiovascular disease. Sialic acid (SA) concentrations have been proposed as a marker of atherosclerotic disease probably related to an inflammatory response of the arterial wall. SA as a marker of cardiovascular disease in adult GH-deficiency and its relation to changes in fasting lipid profile and hormone concentrations have not yet been investigated., Patients: We performed a randomised, double-blind placebo-controlled study in 18 patients with adult GH-deficiency before and after 3 months GH replacement therapy (0.036 U/kg/d; GH-treated group: 6 females, 3 males; age: 47.3 +/- 5.4 years., mean +/- SEM; placebo-group: 5 females, 4 males; mean age 50.2 +/- 4.7). In addition, SA concentrations were measured in 18 sex and age matched healthy control subjects., Methods: Blood samples were obtained after an overnight fast. Serum SA, triglycerides and cholesterol were measured using enzymatic methods. Lipoprotein classes were separated by ultracentrifugation. Insulin and IGF-I were determined by radioimmunoassay, HbA1C was measured by anion exchange liquid chromatography., Results: SA concentrations of the patients with adult GH-deficiency were not significantly different compared to the control group (GH-deficient group: 2.29 +/- 0.02 mmol/l, mean +/- SEM vs. control group: 2.09 +/- 0.13 mmol/l, P = 0.25). Before GH replacement therapy SA concentrations correlated positively with the patients age (r = 0.45; P < 0.04) and fasting insulin concentrations (r = 0.5; P < 0.03) but not with fasting lipid profile. GH replacement therapy significantly increased IGF-I (GH: + 27 +/- 2.6 vs. placebo: + 1.0 +/- 0.8 nmol/l, P < 0.001) and fasting insulin concentrations (GH: + 71.9 +/- 8.0 vs. placebo: + 19.6 +/- 22.6 pmol/l, P < 0.04) compared to placebo therapy. SA concentrations (GH: - 0.41 +/- 0.15 vs. placebo: - 0.01 +/- 0.12 mmol/l, P < 0.05), total cholesterol (GH: - 0.71 +/- 0.16 vs. placebo: 0.23 +/- 0.21 mmol/l, P < 0.003) and LDL-cholesterol (- 0.71 +/- 0.14 vs. placebo: - 0.12 +/- 0.21 mmol/l P < 0.04) significantly decreased after GH replacement therapy compared to placebo therapy. No significant correlation between changes in SA concentrations and changes in lipid profile were observed following GH replacement therapy., Conclusion: These results suggest that, firstly, GH replacement therapy may have a beneficial effect on the pathogenesis of atherosclerosis despite the increase in insulin concentrations, a surrogate marker of insulin resistance, secondly, the proposed beneficial effect of GH on the atherosclerotic process is likely to be multifactorial and cannot only be explained by changes in lipid profile and finally, SA might be a useful marker for the process of atherosclerotic disease in interventional studies.

Despite recent interest in the therapeutic potential of recombinant human insulin-like growth factor-I (rhIGF-I) in the treatment of diabetes mellitus, its mechanism of action is still not defined. We have studied the effects of low-dose bolus subcutaneous rhIGF-I (40 microg/kg and 20 microg/kg) on insulin sensitivity, growth hormone (GH) and glucagon levels in seven young adults with insulin-dependent diabetes mellitus (IDDM) using a randomized double-blind placebo-controlled crossover study design. Each was subjected to a euglycemic clamp (5 mmol/L) protocol consisting of a variable-rate insulin infusion clamp (6:00 PM to 8:00 AM) followed by a two-dose hyperinsulinemic clamp (insulin infusion of 0.75 mU x kg(-1) x min(-1) from 8 to 10 AM and 1.5 mU x kg(-1) x min(-1) from 10 AM to 12 noon) incorporating [6,6 2H2]glucose tracer for determination of glucose production/utilization rates. Following rhIGF-I administration, the serum IGF-I level (mean +/- SEM) increased (40 microg/kg, 655 +/- 90 ng/mL, P < .001; 20 microg/kg, 472 +/- 67 ng/mL, P < .001; placebo, 258 +/- 51 ng/mL). Dose-related reductions in insulin were observed during the period of steady-state euglycemia (1 AM to 8 AM) (40 microg/kg, 48 +/- 5 pmol/L, P = .01; 20 microg/kg, 58 +/- 8 pmol/L, P = .03; placebo, 72 +/- 8 pmol/L). The mean overnight GH level (40 microg/kg, 9.1 +/- 1.4 mU/L, P = .04; 20 microg/kg, 9.6 +/- 2.0 mU/L, P = .12; placebo, 11.3 +/- 1.7 mU/L) and GH pulse amplitude (40 microg/kg, 18.8 +/- 2.9 mU/L, P = .04; 20 microg/kg, 17.0 +/- 3.4 mU/L, P > .05; placebo, 23.0 +/- 3.7 mU/L) were also reduced. No differences in glucagon, IGF binding protein-1 (IGFBP-1), acetoacetate, or beta-hydroxybutyrate levels were found. During the hyperinsulinemic clamp conditions, no differences in glucose utilization were noted, whereas hepatic glucose production was reduced by rhIGF-I 40 microg/kg (P = .05). Our data demonstrate that in subjects with IDDM, low-dose subcutaneous rhIGF-I leads to a dose-dependent reduction in the insulin level for euglycemia overnight that parallels the decrease in overnight GH levels, but glucagon and IGFBP-1 levels remain unchanged. The decreases in hepatic glucose production during the hyperinsulinemic clamp study observed the following day are likely related to GH suppression, although a direct effect by rhIGF-I cannot be entirely discounted.

The availability of recombinant human growth hormone (GH) has resulted in investigation of the role of GH in adulthood and the effects of GH replacement in the GH-deficient adult. These studies have led to the recognition of a specific syndrome of GH-deficiency, characterized by symptoms, signs and investigative findings. Adults with long-standing growth hormone deficiency are often overweight, have altered body composition, with reduced lean body mass (LBM), increased fat mass (FM), reduced total body water and reduced bone mass. In addition, there is reduced physical and cardiac performance, altered substrate metabolism and an abnormal lipid profile predisposing to the development of cardiovascular disease. Adults with GH deficiency report reduced psychological well-being and quality of life. These changes may contribute to the morbidity and premature mortality observed in hypopituitary adults on conventional replacement therapy. GH treatment restores LBM, reduces FM, increases total body water and increases bone mass. Following GH therapy, increases are recorded in exercise capacity and protein synthesis, and "favourable" alterations occur in plasma lipids. In addition, psychological well-being and quality of life improve with replacement therapy. GH is well tolerated; adverse effects are largely related to fluid retention and respond to dose adjustment. It is likely that GH replacement will become standard therapy for the hypopituitary adult in the near future. The benefits of GH replacement in the GH-deficient adult have been unequivocally demonstrated in studies lasting up to 3 years. The results of longer term studies are awaited to determine whether these benefits are sustained over a lifetime.

Mitochondrial encephalomyopathy is a genetic disorder for which there is at present no cure. Conventional treatment regimes may not be effective in preventing weight loss and muscle wasting in many patients. Recombinant human GH has been shown to have anabolic effects on protein metabolism and to reduce muscle wasting in various diseases. We have treated a patient known to have myoclonus, epilepsy with ragged red fibres (MERRF) with a high protein diet for 1 month followed by a high protein diet and GH therapy for 1 month. To assess the benefit of these treatments the patient underwent whole body protein turnover, myometric and body composition studies at baseline, following the high protein diet (100 g/day) and following GH therapy. Whole body protein synthesis (and protein breakdown) increased following a high protein intake and was further enhanced by treatment with GH and in a high protein diet. Body composition did not change significantly following treatment with either the high protein diet or GH but there was an improvement in muscle performance following GH treatment. Mitochondrial encephalomyopathy, a wasting disorder, may be a disease in which the known protein anabolic effect of GH may have a therapeutic benefit.

Using stable isotope techniques to establish turnover rates for very low density lipoprotein (VLDL), a group of eight adult patients with growth hormone deficiency (GHD) exhibited an increased VLDL apoprotein B (apo B) secretion and decreased VLDL apoB metabolic clearance rate compared to controls. Such increased secretion is seen in some dyslipidemic states, including GHD, which are associated with atherosclerosis. The study of VLDL metabolism may provide a clue to the lipid metabolism disorder associated with GHD.

Despite early evidence from studies performed soon after its discovery, the role of human growth hormone (GH) in metabolic processes during adulthood has, until recently, been largely ignored. The importance of GH in the regulation of body composition in the adult is clearly demonstrated by the abnormalities seen in "nature's experiments', i.e. acromegaly and GH deficiency. Body composition has been shown to change favourably following successful treatment of acromegaly. Formal replacement studies in adult GH-deficient patients, made possible by the recent advent of recombinant GH, have also shown dramatic changes in body composition, with increases in lean body mass and reductions in fat mass towards normality and associated improvements in physical performance. Thus, adult GH deficiency, like acromegaly, has become widely accepted as a distinct clinical entity warranting treatment.

Objective: Adult patients with growth hormone deficiency are thought to be at higher risk of mortality from cardiovascular disease. We therefore investigated the effect of recombinant human growth hormone (rhGH) replacement therapy on fasting serum concentrations of lipids, lipoproteins and cholesterol precursors in adult growth hormone deficient patients., Design: Double-blind placebo controlled trial. Patients were randomly allocated to placebo or rhGH replacement therapy (0.018 U/kg/day for 1 month followed by 0.036 U/kg/day for 1 month)., Patients: Eighteen patients with severe growth hormone deficiency., Measurements: Fasting lipid, lipoprotein and cholesterol precursors (lathosterol and mevalonic acid) were measured at baseline and after 2 months., Results: In the rhGH treated group there was a significant fall in serum cholesterol (P < 0.01) (6.44 +/- 0.49 to 5.71 +/- 0.48 mmol/l), LDL cholesterol (P < 0.02) (4.29 +/- 0.49 to 3.62 +/- 0.44 mmol/l), LDL cholesterol/HDL cholesterol ratio (P < 0.02) (3.99 +/- 0.62 to 3.26 +/- 0.39), apolipoprotein B (P < 0.01 (1.30 +/- 0.11 to 1.15 +/- 0.11 g/l) and mevalonic acid (P < 0.05) (13.4 +/- 10.96 to 6.21 +/- 1.91 micrograms/l). There were no significant changes in triglycerides, HDL cholesterol, apolipoprotein A1, lipoprotein (a) or lathosterol concentrations. In the GH treated group the rise in serum insulin was inversely correlated with the fall in cholesterol (P < 0.05), LDL cholesterol (P < 0.01) and apolipoprotein B (P < 0.01). There were no significant changes in any of the measured variables in the placebo group., Conclusion: We conclude that GH may be involved in the regulation of lipid and lipoprotein metabolism and that rhGH replacement therapy of adult GHD patients is associated with beneficial changes in lipid and lipoprotein profiles. The reduction in mevalonic acid is consistent with up-regulation of hepatic LDL receptors caused by GH and this may explain the fall in LDL cholesterol and apolipoprotein B concentrations.

The effects of growth hormone (GH) treatment on protein metabolism were studied in adults with GH deficiency (GHD). A double-blind, placebo-controlled trial of recombinant human GH, 0.018 IU/kg/day for 1 month followed by 0.036 IU/kg/day for 1 month, was performed with isotopic whole-body protein turnover studies at 0 and 2 months. In all, 18 adults with GHD (9 men, 9 women; mean age, 46.6 years; range, 30-56 years) were studied. Whole-body isotopic leucine turnover using L-[1-13C]leucine was assessed by measuring leucine Ra (a measure of protein degradation), non-oxidative leucine Rd (a measure of protein synthesis) and leucine oxidation rate. Lean body mass and circulating insulin-like growth factor I were significantly (p < 0.02) increased at 2 months in the GH-treated group, but not in the placebo group. There was no change in leucine Ra in either the placebo or GH-treated groups at 2 months. Leucine oxidation decreased (p < 0.01) and non-oxidative leucine Rd increased (p < 0.02) in the GH-treated group at 2 months. There was no significant change in either leucine oxidation or non-oxidative leucine Rd in the placebo group at 2 months. These results indicate that the increase in lean body mass resulting from GH treatment in adults with GHD is due to an increase in protein synthesis.

Objective: Growth hormone treatment given to adult growth hormone deficient patients leads to an increase in lean body mass by an unknown mechanism. The aim of this study was to investigate the actions of growth hormone treatment on protein metabolism in adult growth hormone deficient patients., Design: Double-blind, placebo controlled trial of recombinant human growth hormone (0.018 U/kg/day for 1 month followed by 0.036 U/kg/day for 1 month) with isotopic whole body protein turnover studies at 0 and 2 months., Patients: Eighteen adult growth hormone deficient patients (nine male, nine female of mean age 46.6 (range 30-56)., Measurements: Whole body isotopic leucine turnover using L-1-13C-leucine measuring leucine Ra (a measure of protein degradation), non-oxidative leucine Rd (a measure of protein synthesis) and leucine oxidation rate., Results: Lean body mass (P < 0.02), circulating insulin-like growth factor I (P < 0.01) and insulin (P < 0.02) were significantly increased at 2 months in the treatment group but there was no change in the placebo group. When expressed in relation to body weight, leucine Ra and non-oxidative leucine Rd increased (P < 0.01) and leucine oxidation decreased (P < 0.02) after 2 months growth hormone treatment. When expressed in relation to lean body mass non-oxidative leucine Rd increased (P < 0.02) and leucine oxidation decreased (P < 0.02) but there was no significant change in leucine Ra after 2 months growth hormone treatment. In the placebo group there were no significant changes in leucine metabolism expressed as lean body mass or body weight after 2 months. changes in leucine metabolism expressed as lean body mass or body weight after 2 months., Conclusion: These results indicate that the increase in lean body mass resulting from growth hormone treatment in adult growth hormone deficient patients is due to an increase in protein synthesis.