The measurement of insulin-like growth factor I: clinical applications and significance

Effects of oral zinc supplementation on zinc status and catch-up growth during the first 2 years of life in children with non-organic failure to thrive born preterm and at term

BACKGROUND

We aimed to analyze the effect of oral zinc supplementation on serum insulin-like growth factor-1 (IGF-1) levels and catch-up growth in infants with non-organic failure to thrive (NOFTT) who were born preterm as compared to those born at term.

METHODS

Totally, 105 NOFTT infants aged 2 years or less were enrolled and divided into two groups according to gestational age at birth. Oral zinc sulfate was administered for 6 months to 49/66 children born at term, and 21/39 children born preterm. Serum zinc, IGF-1, weight, and height were measured at baseline and at 6 months.

RESULTS

There were no differences in baseline serum zinc levels between the two groups. In preterm NOFTT infants, zinc supplementation significantly increased serum zinc levels compared to those in the non-supplementation group (Δ zinc _{0-6 month} 10.3 ± 26.4 μg/dL vs. -8.8 ± 23.7 μg/dL, p = 0.018), but it did not significantly change serum IGF-1 levels or weight- and height for age Z-scores. In NOFTT infants born at term who received zinc supplementation, serum zinc levels, IGF-1, weight for age Z-score, and height for age Z-score increased at 6 months (p = 0.001, p = 0.014, p = 0.049, and p = 0.029, respectively), but this increase was not significantly greater than in the non-supplementation group. Only the increase in serum zinc levels was significant after 6 months (Δ zinc _{0-6 month} 16.8 ± 32.0 μg/dL vs. -10.0 ± 22.6 μg/dL, p = 0.002).

CONCLUSION

Zinc supplementation in NOFTT infants improves serum zinc status, regardless of gestational age at birth. Zinc supplementation in NOFTT infants born at term may improve serum IGF-1 levels and growth, but it does not in NOFTT infants born preterm. Overall nutritional support rather than supplementation of a single nutrient may be more effective for catch-up growth in NOFTT infants born preterm.

A critical pathway for the management of elderly inpatients with malnutrition: effects on serum insulin-like growth factor-I

BACKGROUND

Several guidelines recommend systematic screening for malnutrition in elderly inpatients for early dietary intakes assessment and treatment, but data demonstrating the efficacy of such interventions are scarce. The aim of this study was to evaluate a critical medical pathway for the detection and management of malnutrition in elderly inpatients.

METHODS

In a 3-month prospective controlled study, 694 recently admitted inpatients were assigned to an intervention group (critical medical pathway; n=465) or a standard care control group (n=229). Nutritional status was assessed at the time of admission with a Mini Nutritional Assessment. A renutrition program tailored to the initial dietary assessment results was applied in the intervention group. The efficacy of the program was verified by measuring the evolution of serum insulin-like growth factor 1 (IGF-I) between admission and 3 weeks later.

RESULTS

In the intervention group at baseline, 23% were malnourished, 51% were at risk and 26% were eunourished. Serum IGF-I increased in the intervention group (from 84±45 μg/l to 95±50 μg/l, P<0.0001; mean±s.d., n=209), but remained stable in the controls (from 79±43 μg/l to 81±35 μg/l, P=0.4; n=99), with a statistically significant between group difference (P<0.01).

CONCLUSION

Early malnutrition assessment and targeted renutrition program in elderly inpatients were associated with an increase in serum IGF-I. It remains to be determined whether such variations are clinically relevant.

Activation of growth hormone releasing hormone (GHRH) receptor stimulates cardiac reverse remodeling after myocardial infarction (MI)

Both cardiac myocytes and cardiac stem cells (CSCs) express the receptor of growth hormone releasing hormone (GHRH), activation of which improves injury responses after myocardial infarction (MI). Here we show that a GHRH-agonist (GHRH-A; JI-38) reverses ventricular remodeling and enhances functional recovery in the setting of chronic MI. This response is mediated entirely by activation of GHRH receptor (GHRHR), as demonstrated by the use of a highly selective GHRH antagonist (MIA-602). One month after MI, animals were randomly assigned to receive: placebo, GHRH-A (JI-38), rat recombinant GH, MIA-602, or a combination of GHRH-A and MIA-602, for a 4-wk period. We assessed cardiac performance and hemodynamics by using echocardiography and micromanometry derived pressure-volume loops. Morphometric measurements were carried out to determine MI size and capillary density, and the expression of GHRHR was assessed by immunofluorescence and quantitative RT-PCR. GHRH-A markedly improved cardiac function as shown by echocardiographic and hemodynamic parameters. MI size was substantially reduced, whereas myocyte and nonmyocyte mitosis was markedly increased by GHRH-A. These effects occurred without increases in circulating levels of growth hormone and insulin-like growth factor I and were, at least partially, nullified by GHRH antagonism, confirming a receptor-mediated mechanism. GHRH-A stimulated CSCs proliferation ex vivo, in a manner offset by MIA-602. Collectively, our findings reveal the importance of the GHRH signaling pathway within the heart. Therapy with GHRH-A although initiated 1 mo after MI substantially improved cardiac performance and reduced infarct size, suggesting a regenerative process. Therefore, activation of GHRHR provides a unique therapeutic approach to reverse remodeling after MI.

Nutritional assessment: its role in the provision of nutritional support

Generalised undernutrition is common in hospital patients and in the community. It is frequently unrecognised and is associated with a range of adverse consequences that contribute to increased morbidity and mortality. The National Institute for Health and Clinical Excellence recommends that all individuals engaging with healthcare or admitted to residential homes in the community should be screened for undernutrition. Laboratory investigations have little place in the diagnosis of undernutrition: this is primarily a clinical process. In particular, the measurement of serum albumin concentration, though widely promulgated in the past as an index of nutritional status, is worthless for this purpose. Laboratory investigations are, however, of importance: to diagnose specific nutritional deficiencies (eg, of trace elements) and to monitor the provision of nutritional support, to detect metabolic complications and to assess its adequacy (for which the measurement of serum prealbumin concentrations, particularly in conjunction with measurements of C-reactive protein, may be of value).

Elderly patients and high force resistance exercise--a descriptive report: can an anabolic, muscle growth response occur without muscle damage or inflammation?

BACKGROUND AND PURPOSE

Elderly individuals participate in resistance exercise to induce an anabolic response and grow muscle to help overcome functional deficits. It is thought that a muscle damage and inflammatory response to resistance exercise is a necessary prerequisite for an anabolic and muscle growth response.

METHODS

This is a descriptive study of 11 elderly individuals in rehabilitation who underwent a 2-3x/week high force resistance exercise that used eccentric contractions. Serum measures of muscle damage, inflammation, and an anabolic response are reported along with changes in muscle mass as measured with dual energy X-ray absorptiometry.

RESULTS

Negative work increased >3-fold during the 11 weeks of resistance exercise. There were no significant changes in the damage measure of serum creatine kinase (pretraining: 18.5 +/- 1.2 Sigma units/ml; post-training: 19.2 +/- 1.1 Sigma units/ml). Proinflammatory tumor necrosis factor-alpha values remained within normal range (<4.0 pg/ml) throughout the 11 weeks of training. A nonsignificant trend for an anabolic increase (65%) in insulin like growth factor-1 was noted along with a significant increase (6%) in thigh muscle mass.

CONCLUSIONS

Neither damage, nor inflammation appear to be prerequisites for inducing anabolic and muscle growth responses in elderly individuals undergoing a high force resistance exercise with eccentric contractions.

Chronic inflammation and the effect of IGF-I on muscle strength and power in older persons

Deregulation of the inflammatory response plays a major role in the age-related decline of physical performance. The causal pathway leading from inflammation to disability has not been fully clarified, but several researches suggest that interleukin-6 (IL-6) causes a reduction of physical performance in elderly through its effect on muscle function. In vitro studies demonstrated that IL-6 inhibits the secretion of insulin-like growth factor I (IGF-I) and its biological activity, suggesting that the negative effect of IL-6 on muscle function might be mediated through IGF-I. We evaluated the joint effect of IGF-I and IL-6 on muscle function in a population-based sample of 526 persons with a wide age range (20-102 yr). After adjusting for potential confounders, such as age, sex, body mass index, IL-6 receptor, and IL-6 promoter polymorphism, IL-6, IGF-I, and their interaction were significant predictors of handgrip and muscle power. In analyses stratified by IL-6 tertiles, IGF-I was an independent predictor of muscle function only in subjects in the lowest IL-6 tertile, suggesting that the effect of IGF-I on muscle function depends on IL-6 levels. This mechanism may explain why IL-6 is a strong risk factor for disability.

Recombinant human growth hormone treatment in elderly patients undergoing elective total hip replacement

OBJECTIVE

Measures to prevent postoperative catabolism may be of greatest benefit in the elderly because of their reduced lean tissue reserve. We examined the effects of recombinant human growth hormone (GH) treatment on body composition and physical performance in elderly patients undergoing elective total hip replacement.

METHODS

We recruited 33 patients (aged 60-82 years) scheduled for hip replacement. The study was double-blind and placebo-controlled with parallel groups. GH or placebo was administered for 14 weeks preoperatively (target GH dose 0.04 U/kg/day) and 4 weeks postoperatively (with dose doubled for first 2 weeks postoperatively). Serum IGF-I, body composition, mid-thigh muscle cross-sectional area, muscle strength and 4-min walking distance were measured at baseline, 2-3 days preoperatively and 4 weeks postoperatively.

RESULTS

Mean serum IGF-I doubled during GH treatment. Lean body mass increased preoperatively by an average of 5.2% (representing 1.8 kg) with GH treatment (P < 0.05 vs. placebo), but fell postoperatively by 3% in both groups. Similar changes pre- and postoperatively were seen for mid-thigh muscle cross-sectional area, such that there was no net loss in the GH group but a fall of more than 10% in the placebo group (P < 0.005 vs. GH). There was a trend towards a favourable effect of GH on strength in the majority of muscles tested, but this was significant only for the abductors of the nonoperated hip (P < 0.02), where there was a 7% increase in strength over the whole study compared with a 25% decrease in the placebo group. Four-minute walking distance improved postoperatively by a mean of 26.9 m in the GH group compared with a 19.5 m reduction in the placebo group (P < 0.05). Dose-related side-effects were seen in the majority of patients receiving GH.

CONCLUSIONS

In elderly patients undergoing total hip replacement, preoperative GH treatment results in improvements in lean body mass and skeletal muscle mass that are sufficient to offset postoperative losses. The treatment may also preserve or improve muscle strength and postoperative walking ability.

Supraphysiological doses of GH induce rapid changes in cardiac morphology and function

GH is an agent widely used in sport to improve physical performance and has been proposed as adjunctive therapy in several clinical conditions. However, its short-term effects on the normal human heart are poorly understood. Sixty young normal volunteers (30 males and 30 females) were enrolled in a multicenter, double-blind, placebo-controlled study. All subjects were randomized to receive GH (0.03 or 0.06 mg/kg.d) or placebo. A complete Doppler-echocardiographic examination was performed at baseline and after 4 wk of treatment. Low-dose GH did not significantly affect echocardiographic parameters. In contrast, high-dose GH increased left ventricular mass index by 12% (P < 0.05). The type of growth response was concentric, because left ventricular wall thickness but not diameter increased, leading to a 10% increase of relative wall thickness. These structural changes were associated with functional changes, including a significant increase in cardiac index and a decrease in peripheral vascular resistance; diastolic function was not altered. Fractional shortening and systemic blood pressure were unchanged in the two treatment groups. In conclusion, administration of GH for 4 wk at doses that simulate GH abuse in sport caused a high cardiac output state associated with concentric left ventricular remodeling.

The effect of 24 months recombinant human growth hormone (rh-GH) on LDL cholesterol, triglyceride-rich lipoproteins and apo [a] in hypopituitary adults previously treated with conventional replacement therapy

Hypopituitary adults receiving conventional hormone replacement therapy are reported to have increased cardiovascular mortality. Previous studies indicate that these patients have several abnormalities in lipoprotein metabolism, including reduced low density lipoprotein (LDL) uptake and impaired metabolism of triglyceride-rich lipoproteins. The effects of 24 months of 0.21 IU/kg per week recombinant growth hormone (rh-GH) on the lipoprotein profiles of 22 GH-deficient adults were studied. Samples were collected after a 12-h fast at baseline and 24 months. Total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, apolipoprotein (apo) A, apo B and apo [a] were determined by routine laboratory methods. LDL particle size was determined by non-denaturing gradient gel electrophoresis. Visceral adiposity was determined by dual energy X-ray absorptiometry (DEXA). Insulin sensitivity was measured in a subset of 17 subjects using a two-stage hyperinsulinaemic-euglycaemic clamp. Significant reductions were observed in total cholesterol (5.3 +/- 0. 17 vs 4.9 +/- 0.23 mmol/l;P<0.05) and LDL cholesterol (3.4 +/- 0.17 vs 2.9 +/- 0.17 mmol/l; P<0.001) at 24 months when compared to baseline. No significant changes were observed in triglyceride level, HDL cholesterol level, apo B, apo A and LDL size. A significant increase in apo [a] [160 (96-416) vs 204 (127-534) U/l;P<0.05] was observed which appeared to be dose-dependent. Visceral adiposity was reduced significantly. Insulin sensitivity did not alter significantly. Replacement for 24 months with rh-GH has a differential effect on the lipid profile with a decrease in LDL, but little effect upon the metabolism of triglyceride-rich lipoproteins, manifested by unchanged triglyceride, HDL cholesterol levels and LDL size, despite the reduction in visceral adiposity. Conversely, apo [a], an independent risk factor for cardiovascular disease was increased. The ultimate effect of GH therapy upon cardiovascular mortality remains to be determined and may be dose-related.

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.

Effect of recombinant human growth hormone treatment on insulin-like growth factor (IGF-I) levels in insulin-dependent diabetic patients

Basal and recombinant human growth hormone (rhGH)-stimulated insulin-like growth factor (IGF-I) levels were studied in 19 insulin-dependent diabetic patients and 4 healthy subjects. Diabetic patients were divided according to glucagon test result into CpN (10 patients without residual beta cell activity) and CpP (9 patients with preserved beta-cell activity) and CpP (9 patients with preserved beta-cell activity) groups, and according to age into three groups (A = 21-30 years; B = 31-40 years; C = 41-50 years). All control subjects belonged to group B. Blood glucose and growth hormone were measured at hourly intervals and IGF-I every 6 h during 24 h before and after 7 days treatment with 4 IU of rhGH given subcutaneously at 8 p.m. The age-related decrease in basal IGF-I levels was evident in both CpN and CpP groups of diabetic patients. IGF-I net increase with rhGH treatment was variable and insignificant in comparison with basal value without age-related differences in CpN diabetics. Progressively larger, age-related increases in IGF-I concentrations were observed in CpP diabetic patients. This study indicates impairment of hepatic IGF-I generation capacity in diabetic patients without residual beta-cell activity and the importance of simultaneous actions of portal insulin and GH on hepatic IGF-I production.

An evaluation of insulin-like growth factor-1 as anindicator of nutritional status

This study evaluated the usefulness of insulin-like growth factor-1 (IGF-1) as a marker of nutritional status in 185 hospitalised patients compared with conventional biochemical (albumin) and anthropometric parameters. C-reactive protein (CRP) was used as a biochemical marker of underlying illness. 77 (42%) patients were normally nourished or overweight and 108 (58%) were nutritionally depleted. IGF-1 and albumin were significantly lower in the malnourished patients as a group. However, in the malnourished patients with normal CRP, there was no correlation between albumin or anthropometric measurements and IFG-1. In malnourished patients with a raised CRP, there was no relationship between malnutrition determined by body mass index and anthropometry and either albumin of IGF-1 concentrations. In normally nourished patients with a raised CRP, there was a relationship between albumin and CRP; and IGF-1 and CRP and between albumin and IGF-1. IGF-1 was related to age in all groups of patients. We conclude that neither albumin nor IGF-1 can be reliably used to assess nutritional status.

Abnormal body composition and reduced bone mass in growth hormone deficient hypopituitary adults

OBJECTIVES

The role of growth hormone in maintaining normal body composition and bone strength in adults has attracted much interest recently. We have assessed body composition and bone mass in GH deficient hypopituitary adults on conventional replacement therapy and compared them with matched controls.

DESIGN AND SUBJECTS

A cross-sectional study of 64 growth hormone deficient hypopituitary adults (29 males and 35 females) on conventional replacement therapy and a large number of healthy control subjects matched for age, sex and body mass index (BMI).

MEASUREMENTS

Skinfold thicknesses at two sites (triceps and subscapular), waist and hip girth circumferences were assessed by standard methods. Body composition was assessed using total body potassium (TBK), bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA). Bone mineral mass was assessed at the lumbar spine and the total body by DEXA. Not every patient and control participated in every measurement.

RESULTS

Obesity was common in the hypopituitary patients; BMI (mean +/- SD) was 27.5 +/- 4.6 kg/m2 and body weight was 111.8 +/- 18.5% of the maximal ideal for height (P < 0.001). The sum of subscapular and triceps skinfolds was significantly higher in hypopituitary patients than in controls (men 46 + 15 vs 37 +/- 14 mm, P < 0.05; women 55 +/- 13 vs 47 +/- 17 mm, P < 0.05). Waist to hip circumference ratio was significantly greater in female hypopituitary patients than in matched controls but was not significantly different in men (men 0.94 +/- 0.07 vs 0.91 +/- 0.07, NS; women 0.84 +/- 0.09 vs 0.77 +/- 0.05, P < 0.001). The difference between patients and controls in the sum of skinfolds and the waist to hip ratio were present in non-obese (BMI < 26 kg/m2) subjects (21 patients and 32 controls). TBK corrected for body weight was significantly lower in hypopituitary patients (n = 44) than in controls (n = 31) (men 43.5 +/- 5.6 vs 50.1 +/- 5.9 mmol/kg, P < 0.003; women: 34.0 +/- 3.2 vs 40.6 +/- 5.3 mmol/kg, P < 0.0001). BIA-derived body water content (corrected for body weight) was significantly lower in hypopituitary patients (n = 56) than in controls (n = 57) (0.492 +/- 0.064 vs 0.545 +/- 0.067 l/kg, P < 0.0004). Percentage body fat derived from all the three methods was significantly higher in hypopituitary patients than in normal controls in both sexes (from TBK: men 34.7 +/- 9.4 vs 28.8 +/- 7.0%, P < 0.05; women 37.8 +/- 8.7 vs 30.4 +/- 9.7%, P < 0.01; from BIA: men 29.3 +/- 8.5 vs 23.2 +/- 8.4%, P < 0.01; women 34.6 +/- 8.1 vs 29.3 +/- 9.1% P < 0.01; and from DEXA: men 24.8 +/- 6.8 vs 20.4 +/- 6.1%, P < 0.05; women 38.9 +/- 7.9 vs 32.5 +/- 9.8%, P < 0.01). There was a significant difference between non-obese patients and controls in BIA-derived percentage fat in both sexes and in TBK-derived percentage fat in females only. Bone mineral density (BMD) of the lumbar spine in the L2-L4 region was lower in hypopituitary patients than in controls (men 1.116 +/- 0.129 vs 1.311 +/- 0.131 g/cm2, P < 0.0001; women 1.001 +/- 0.122 vs 1.131 +/- 0.138 g/cm2, P < 0.001). Spine BMD was also reduced in hypopituitary patients compared to the young adult and age and weight matched reference data. Total body BMD was significantly lower in patients than in controls (men 1.186 +/- 0.102 vs 1.250 +/- 0.080 g/cm2, P < 0.05; women 1.080 +/- 0.077 vs 1.149 +/- 0.073 g/cm2, P < 0.005).

CONCLUSIONS

Hypopituitary adults on conventional therapy have abnormal body composition with increased fat content, reduced body water content and reduced bone mineral mass.

Replacement treatment with biosynthetic human growth hormone in growth hormone-deficient hypopituitary adults

OBJECTIVES

The physiological role of growth hormone in adult life has recently attracted increased interest. We have studied the clinical effects and the effects on body composition of prolonged replacement with biosynthetic human GH in a large number of hypopituitary adults.

DESIGN

A randomized double blind placebo controlled trial for 6 months followed by an open trial of GH treatment for 12 months. GH daily dose was 0.04 (0.02-0.05) IU/kg s.c.

PATIENTS

Forty GH deficient hypopituitary patients (19 M, 21 F; aged 19-67 years) on conventional replacement therapy were studied.

MEASUREMENTS

Serum insulin like growth factor I (IGF-I), skinfold thickness, total body potassium, total body water (TBW), exercise tolerance and muscle strength, and well-being.

RESULTS

During the 6-month double blind phase, two GH treated patients withdrew because of adverse events. Lean body mass (LBM) increased and percentage body fat (%BF) decreased on GH but not on placebo (P) (LBM: (GH: from 48.5 +/- 9.6 to 49.6 +/- 9.5 kg; P: from 50.9 +/- 9.2 to 50.1 +/- 9.0 kg, P < 0.05 GH vs P) and %BF (GH: from 34.7 +/- 11.4 to 34.2 +/- 10.7; P: from 37.4 +/- 7.6 to 38.7 +/- 8.1, P < 0.05 GH vs P)). TBW increased on GH (P < 0.01) but not on P. No change was observed in waist-to-hip ratio or in muscle strength. During longer-term follow-up combining the double blind and open phase components of the study, 34, 27 and 11 patients received GH for 6, 12 and 18 months respectively. Patients dropped out because of adverse events or lack of perceived benefit. Skinfold thicknesses decreased significantly at 6 and 12 months and the waist circumference at 6 months. Waist-to-hip ratio decreased significantly on GH at 12 months. LBM increased on GH treatment from 49.6 +/- 9.1 to 51.6 +/- 9.4 kg (P < 0.0006), 51.9 +/- 8.9 kg (P < 0.07) and 53.1 +/- 10.5 kg (P < 0.0001) at 6, 12 and 18 months respectively. Percentage body fat decreased on GH from 37.2 +/- 10.7 to 34.7 +/- 10.1 (P < 0.005), 35.1 +/- 12.8 (NS) and 34.5 +/- 8.6 (P < 0.04) at 6,12 and 18 months respectively. TBW also increased at 6 and 12 months of GH treatment. Exercise time increased significantly at 6, 12 and 18 months of GH treatment. Muscle strength in selected muscle groups increased significantly at 6, 12 or 18 months of GH treatment. Randomization resulted in the placebo group having a greater GHQ score (higher morbidity) than the GH group before therapy. Over the controlled phase, GHQ scores improved on placebo but not on GH and CPRS score was unchanged in either group. In the open phase, the GHQ score did not change on GH therapy but CPRS score improved at 6 and 12 months.

CONCLUSIONS

Growth hormone replacement therapy in adults for 6 months increased lean body mass, total body water and exercise tolerance, and decreased body fat. Growth hormone replacement for longer than 6 months maintains the advantageous effects seen in shorter-term studies and may have additional effects on body fat distribution, muscle strength and psychological well-being.

Effect of glucocorticoid replacement therapy on glucose tolerance and intermediary metabolites in hypopituitary adults

BACKGROUND AND OBJECTIVES

Excess impaired glucose tolerance and diabetes mellitus have been reported in hypopituitary adults on conventional replacement therapy including glucocorticoids. We investigated the effect of the glucocorticoid component on glucose tolerance and intermediary metabolites in hypopituitary adults.

DESIGN

A 3-hour 75-g oral glucose tolerance test (OGTT) was performed on two study days, at least one week apart. On one study day, the glucocorticoid replacement morning dose was taken 60 minutes before the OGTT, and on the other it was left until after the OGTT. All other pituitary replacement therapies were kept unchanged on the two study days.

PATIENTS

Eight hypopituitary adults (3 males and 5 females; aged 46-76 years) on conventional replacement therapy were studied. Their duration of hypopituitarism was mean (range) 15 (5-31) years. Their mean body mass index (BMI) was 28.4 (24.1-35.1) kg/m2. Their total daily cortisol dose was 26 (15-30) mg.

MEASUREMENTS

Plasma glucose, insulin, non-esterified fatty acids (NEFA), glycerol and 3-hydroxybutyrate were measured at 30-minute intervals and plasma cortisol levels were measured hourly.

RESULTS

Fasting glucose and insulin concentrations were similar on the glucocorticoid day (GD) and the non-glucocorticoid day (NGD) (glucose (mean +/- SD) 4.9 +/- 0.9 vs 4.4 +/- 0.5 mmol/l; insulin (median (range)) 5 (1-17) vs 2 (1-15) mU/l, respectively). Post-glucose glycaemia was higher on the GD than on the NGD with a significantly higher glucose area under the curve (AUC) (45.0 +/- 8.2 vs 38.9 +/- 11.7 mmol/l h, P < 0.05). Post-glucose insulinaemia was also higher on the GD than on the NGD with significantly higher insulin AUC (270 (47-909) vs 207 (46-687) mU/l h, P < 0.02). Impaired glucose tolerance was found in three patients on the GD, one of whom continued to have impaired glucose tolerance on the NGD. The areas under the curves of NEFA, glycerol and 3-hydroxybutyrate were not significantly different on the two days. On the NGD, plasma cortisol levels were undetectable (< 50 nmol/l) in all patients and on the GD the median (range) peak was 500 (330-740) nmol/l dropping to 125 (60-330) nmol/l at 180 minutes. The difference in glucose AUC between the two days correlated with the maximal plasma cortisol levels (Spearman's p = 0.83, P < 0.01).

CONCLUSIONS

Glucocorticoid replacement therapy taken pre-prandially in hypopituitary adults induces mild elevations in circulating glucose and insulin levels even with acceptable plasma cortisol concentrations. Optimal regimens for glucocorticoid replacement require more study.

The effect of growth hormone replacement therapy in hypopituitary adults on calcium and bone metabolism

OBJECTIVE

The importance of growth hormone (GH) for normal skeletal growth in childhood and adolescence is well established but much less is known about its action on the adult skeleton. We therefore wished to investigate the effects of replacement treatment with biosynthetic human GH in hypopituitary adults on aspects of calcium homeostasis, bone metabolism and bone mineral mass.

PATIENTS

Forty hypopituitary adults (21 females and 19 males; aged 19-67 years).

DESIGN

A prospective randomized double-blind placebo-controlled trial lasting for 6 months.

PROTOCOL

Following baseline assessments, GH was given in a daily dose of 0.02-0.05 IU/kg body weight subcutaneously (or a placebo (P)) at bedtime. Patients were reviewed at 1, 3 and 6 months.

MEASUREMENTS

Plasma calcium, phosphate and total plasma alkaline phosphatase were measured at 0, 1, 3 and 6 months. Serum insulin like growth factor I (IGF-I), osteocalcin, procollagen 1 carboxyterminal peptide (P1CP) and intact parathyroid hormone (PTH) level, 24-hour urinary calcium and creatinine excretion were all measured at 0 and 6 months. Bone mineral density of total body and lumbar spine was also measured by dual energy X-ray absorptiometry at 0 and 6 months in 12 patients on GH and 14 on placebo.

RESULTS

Thirty-eight patients completed the study (18 on GH, 20 on placebo). Serum IGF-I increased significantly on GH treatment (mean +/- SD) (GH: 276 +/- 197 vs P: 88 +/- 50 micrograms/l, P < 0.0001 at 6 months). Plasma calcium increased slightly but significantly in the GH-treated group (2.23 +/- 0.11-2.29 +/- 0.11 mmol/l, P < 0.05). At the end of the study, plasma calcium was however similar on GH and placebo (GH, 2.29 +/- 0.11; P, 2.26 +/- 0.09 mmol/l). Plasma phosphate increased on GH (GH: 1.02 +/- 0.23-1.32 +/- 0.19; P: 0.99 +/- 0.16-0.96 +/- 0.12 mmol/l over the 6 months of treatment, P < 0.001). There was no significant change in the urinary calcium excretion on GH therapy. Plasma total alkaline phosphatase, osteocalcin and P1CP were significantly higher on GH than P at 6 months (alkaline phosphatase: GH: 104 +/- 32 vs P: 69 +/- 32 U/l, P < 0.01, osteocalcin: GH: 17.2 +/- 8.0 vs P: 5.3 +/- 3.2 micrograms/l, P < 0.001 and P1CP: GH: 207 +/- 152 vs P: 93 +/- 31 micrograms/l, P < 0.01). There was no difference in the intact parathyroid hormone level (GH: 31 +/- 14 vs P: 31 +/- 15 ng/l, NS). No significant change was observed in bone mass after 6 months of GH treatment, either in total body bone mineral content or in the lumbar spine.

CONCLUSION

In this large study, GH replacement in hypopituitary adults for 6 months increased bone turnover but did not affect bone mineral content. Longer-term studies are required to assess further any effect on bone mass.

Acute IGF-1 deficiency in multiple trauma victims

The circulating levels of IGF-1 in the catabolic flow phase of injury were measured in multiple trauma victims once before nutritional support and again after 4 days of intravenous feeding. The hypermetabolic and highly catabolic state of injury is characterized by a diminished level of IGF-1 along with increased levels of stress hormones. Inverse relationships of adiposity and aging on IGF-1 levels are seen both in injured and uninjured subjects. Feeding could restore the IGF-1 levels in non-obese, young patients but it is delayed in obese or elderly subjects. This diminished responsiveness to feeding of IGF-1 hormone deficiency in obese and elderly subjects should be taken into consideration in their post-trauma treatment and may warrant adjuvant administration in these types of patients.

Detection of premature atherosclerosis by high-resolution ultrasonography in symptom-free hypopituitary adults

Retrospective analysis suggests that there is increased mortality from vascular disease in hypopituitary adults, but vascular status before death is unknown. High resolution B-mode ultrasonic imaging of both carotid and femoral arteries was therefore done in 34 adult hypopituitary patients on routine replacement therapy and was compared with that in 39 matched controls. Changes were related to risk factors for vascular disease. Carotid intima-media thickness was greater in patients than in controls (mean [SD] 0.74 [0.16] vs 0.65 [0.13] mm, p < 0.02). This difference was seen in middle-aged and elderly patients. More patients than controls had one or more atheromatous plaques (65% vs 41%, p < 0.05). The percentage of individual arteries with a plaque was also higher in patients (32% vs 18%, p < 0.005). In multiple regression analysis, patients' age was the dominant factor determining carotid intima-media thickness. Symptom-free adults with hypopituitarism show an increased prevalence of atherosclerosis.

Alleviation of non-islet cell tumour hypoglycaemia by growth hormone therapy is associated with changes in IGF binding protein-3

The hypoglycaemia caused by non-islet cell tumours is often associated with an increase in plasma insulin-like activity. In many cases there is a relative if not always absolute increase in plasma insulin-like growth factor II (IGF-II). Growth hormone (GH) secretion is almost invariably depressed as is the plasma insulin response to oral glucose. Despite the high concentration of IGFs (i.e. IGF-I and IGF-II) normally found in the plasma of healthy people their potential hypoglycaemic effect is not manifest due to the tightness with which they are bound to specific binding proteins (IGFBPs). Plasma levels of the major binding protein (IGFBP-3), which is GH-dependent, were depressed in three patients with tumour induced hypoglycaemia. Treatment with biosynthetic GH restored IGFBP-3 to levels which were approximately equimolar to total plasma IGF concentrations, alleviated the hypoglycaemia and restored the plasma insulin responses to oral glucose. We suggest that after GH treatment IGF-II is sequestered by stimulated IGFBP-3 in association with a pre-existing acid-labile subunit to form high molecular weight complexes which prevent IGF-II gaining access to tissues receptors through which it exerts its hypoglycaemic effects.

Insulin-like growth factor 1: a valid nutritional indicator during parenteral feeding of patients suffering an acute phase response

Insulin-like growth factor 1 (IGF-1) is regulated by nutritional intake independently of growth hormone and may be a better nutritional indicator than the plasma proteins. This possibility was investigated in six malnourished inpatients, who suffered sepsis, surgical trauma, or both and who received total parenteral nutrition (TPN) for 10-35 days. Both plasma IGF-1 and pre-albumin showed (P less than 0.05) increases during TPN from baseline values of 0.042-0.42 U/mL (median, 0.11) and 59-156 mg/L (median, 108), respectively, to maxima of 0.19-1.12 U/mL (median, 0.63) and 140-363 mg/L (median, 203). Statistically significant (P less than 0.05) positive correlation occurred between nitrogen balance (range, -7.5 to +11.0 g/day) and IGF-1 or pre-albumin. Correlation between nitrogen balance and IGF-1 is preserved during the acute phase response to tissue injury when C-reactive protein (CRP) varies in the range 40-248 mg/L. Under these circumstances, the correlation between nitrogen balance and pre-albumin is, in contrast, abolished. These results suggest that IGF-1 behaves as a valid index of nutritional adequacy during parenteral feeding whereas pre-albumin reflects mainly the acute phase response.

Improvement in endocrine and ovarian function during dietary treatment of obese women with polycystic ovary syndrome

OBJECTIVE

Obese women with polycystic ovary syndrome have a greater frequency of menstrual disturbance and of hirsutism than lean women with the syndrome. Initial studies have demonstrated a marked improvement in endocrine function following a short-term, very low calorie diet. The purpose of this study was to examine the effect of long-term calorie restriction on clinical as well as biochemical abnormalities in obese women with polycystic ovary syndrome.

DESIGN

We performed a within-group comparison of clinical and biochemical indices before and during dietary treatment.

PATIENTS

Twenty-four obese women with polycystic ovary syndrome (mean weight 91.5 (SD 14.7) kg) were scheduled for treatment for 6-7 months with a 1000 kcal, low fat diet. Nineteen of the 24 had menstrual disturbances, 12 had infertility and 19 were hirsute.

MEASUREMENTS AND RESULTS

Thirteen subjects lost more than 5% of their starting weight (range 5.9-22%). In this group there was no significant change in gonadotrophin or total serum testosterone levels but there was a marked increase in concentrations of sex hormone-binding globulin (pretreatment: 23.6 (9.5); post-treatment 36.3 (11.8) nmol/l, P = 0.002) and a reciprocal change in free testosterone levels (77 (26) vs 53 (21) pmol/l, P = 0.009). These changes were accompanied by a reduction in fasting serum insulin levels (median (range) 11.2 (5.2-32) vs 2.3 (0.1-13.8) mU/l, P = 0.018) and the insulin response to 75 g oral glucose. There were no significant changes in these indices in the group who lost less than 5% of their initial body weight. Of the 13 women who lost greater than 5% of their pretreatment weight, 11 had menstrual dysfunction. Amongst these women, nine of 11 showed an improvement in reproductive function, i.e. they either conceived (five) or experienced a more regular menstrual pattern. There was a reduction in hirsutism in 40% of the women in this group. By contrast, in the group who lost less than 5% of their initial weight, only one of the eight with menstrual disturbances noted an improvement in reproductive function and none had a significant reduction in hirsutism.

CONCLUSIONS

These data indicate that moderate weight loss during long-term calorie restriction is associated with a marked clinical improvement which reflects the reduction in insulin concentrations and reciprocal changes in SHBG. The improvement in menstrual function and fertility may therefore be consequent upon an increase in insulin sensitivity which, directly or indirectly, affects ovarian function.

Myocardial dysfunction in treated adult hypopituitarism: a possible explanation for increased cardiovascular mortality

OBJECTIVE

To assess cardiac structure and function in patients with treated hypopituitarism and to determine their relation to the degree of growth hormone deficiency and body composition pattern.

DESIGN

26 patients with treated hypopituitarism were studied by cross sectional and Doppler echocardiography and by exercise testing. The results were analysed and their relation to the degree of growth hormone deficiency and body composition determined.

SETTING

All tests were performed in the department of cardiology and the unit of metabolic medicine at a tertiary referral centre.

PATIENTS

Patients with hypopituitarism referred for endocrine assessment.

MAIN OUTCOME MEASURES

Left ventricular mass, left ventricular diastolic function, and exercise capacity in patients with hypopituitarism and their relation to growth hormone deficiency.

RESULTS

Mean (SD) serum concentration of insulin-like growth factor 1 (IGE-1), a measure of growth hormone deficiency, was 82.4 (45) micrograms/l. Lean body mass calculated by measuring total body potassium was 50 (9) kg. All patients had a normal left ventricular mass index and a normal left ventricular ejection fraction. Eight patients had abnormal left ventricular diastolic function. There was a significant correlation between IGF-1 and left ventricular mass (r = 0.45, p less than 0.02). Lean body mass was also significantly correlated with left ventricular mass (r = 0.78, p less than 0.0001) and left ventricular diastolic function (r = -0.63, p less than 0.01). The mean exercise duration was 8.6 (3.6) minutes. There was a significant correlation between serum IGF-1 and the rate-pressure product on exercise (r = 0.47, p less than 0.01). Seven patients had planar ST segment depression greater than 0.1 mV during exercise testing. In five of these patients there was rapid resolution of ST segment depression immediately after exercise. Two patients developed considerable ST segment depression, and subsequent coronary angiography showed normal coronary arteries. Exercise-induced ST segment depression was not related to the severity or duration of growth hormone deficiency or serum cholesterol concentration.

CONCLUSIONS

This study suggests that left ventricular mass and the rate-pressure product are related to the degree of growth hormone deficiency, that left ventricular diastolic dysfunction is frequently seen in hypopituitarism, and that these patients may have ischaemic-like ST segment changes during exercise testing. These findings may explain the increased cardiovascular mortality in patients with hypopituitarism and may also have implications for growth hormone replacement therapy in adults.

The effect of subcutaneous injection site on absorption of human growth hormone: abdomen versus thigh

OBJECTIVES

To investigate whether growth hormone (GH) absorption is site dependent.

DESIGN AND MEASUREMENTS

Human growth hormone (hGH, Norditropin) 4 IU, was injected subcutaneously on two separate occasions: into the thigh on one occasion and into the abdomen on a second occasion. Blood was sampled for GH, insulin, glucose, non-esterified fatty acids and glycerol at baseline and hourly for 12 hours. Serum insulin-like growth factor I was measured at baseline, and after 12 and 24 hours.

SUBJECTS

Eleven healthy young adults (8 M, 3 F).

RESULTS

Following the injection serum GH had risen by 1 hour and peaked by 3-6 hours. The peak GH and growth hormone area under the curve were significantly higher after injection in the abdomen compared with the thigh (GH peak (mean +/- SEM) 103 +/- 20 vs 41 +/- 8 mU/l, P = 0.002 and GH area 528 +/- 86 vs 239 +/- 34 mU/l h, P = 0.003 respectively). Serum insulin-like growth factor I at 12 and at 24 hours showed a significant rise from the baseline level, but no significant difference was observed between the two injection sites. No significant difference in plasma insulin, glucose, non-esterified fatty acids or glycerol was observed between the two methods of injection.

CONCLUSION

Subcutaneously injected GH is better absorbed from the abdominal site than from the thigh.

Experimental and clinical studies with somatostatin analogue octreotide in small cell lung cancer

We have detected somatostatin receptors (SSR) by autoradiography in 3/4 established small cell lung cancer (SCLC) cell lines but not in two non-SCLC cell lines. The growth of 1/3 SSR positive SCLC cell lines was significantly inhibited by the long-acting somatostatin analogue octreotide (SMS 201-995, Sandostatin) 10(-9) M. We treated 20 SCLC patients with octreotide 250 micrograms three times daily for 1 week prechemotherapy (six patients) or at relapse after chemotherapy (14). Octreotide was well tolerated, and serum insulin-like growth factor-I levels were suppressed to 62 +/- 7% of pre-treatment levels. However there was no evidence of anti-tumour activity measured by tumour bulk or serum levels of neuron-specific enolase. In one patient metastatic skin nodules were shown to be SSR positive before and at the end of 2 weeks octreotide. Despite this the patient had progressive disease, and tumour cells obtained by fine needle aspirate before and after treatment showed no growth inhibition when cultured with octreotide immediately or following establishment as a cell line. In summary we saw little correlation between SSR expression and growth inhibition by octreotide, either in vitro or clinically.

Insulin-like growth factor 1 (IGF-1) in burn patients

Variations in growth factor IGF-1 levels during wound healing were assessed in 23 patients with burns of varying extent and severity. The patients were followed during the postburn period and the IGF-1 levels were regularly measured by radioimmunoassay. All patients with large burns had reduced IGF-1 levels which correlated with the surface area of burn. The most plausible reason for the suppressed IGF-1 level in these patients may be diffusion from the burned skin as we have found a strong correlation between IGF-1 and serum albumin. The reduced IGF-1 levels may contribute to impaired wound healing in these patients.

Twin very low birth weight infants: a study of nutritional and hormonal status

Nonidentical twin male infants (twin 1,950 g birth weight, twin 2,970 g) had their nutritional and hormone status studied for up to 59 days. Both infants received parenteral nutrition up to 32 days postnatally; enteral feeding was then established in twin 1; in twin 2 parenteral feeding was recommenced on day 35, for the remainder of the study. Serial 72-hr metabolic balances were performed in both infants at 4, 32, 45, and 56 days postnatally. Insulin-like growth factor I (IGF-I) and growth hormone were assayed on day 2 of each balance. During the course of the study growth was similar in each infant. Overall mean daily energy intakes were 90 kcal/kg/day and 84 kcal/kg/day and percentage nitrogen retention was 62% and 55% in twin 1 and twin 2, respectively. No differences were observed between the two infants in IGF-I or growth hormone. Despite low energy intakes incremental weights were within an acceptable range for both infants.

Inappropriately elevated plasma insulin-like growth factor II in relation to suppressed insulin-like growth factor I in the diagnosis of non-islet cell tumour hypoglycaemia

The diagnosis of non-islet cell tumour (hypoinsulinaemic) hypoglycamia has been complicated by contradictory biochemical evidence. Although insulin-like growth factor II (IGF-II) has been identified as the hypoglycaemic agent, plasma levels are often not elevated. In this study specific radioimmunoassay procedures for the measurement of IGF-I and IGF-II are described. Reference data on plasma IGF-II concentrations in relation to a wide range of IGF-I levels have been accumulated using plasma samples from acromegalic, hypopituitary and insulinoma (i.e. hyperinsulinaemic hypoglycaemia) patients as well as normal subjects from all age groups. The reference data indicate that a low plasma IGF-I value is normally associated with a relatively low plasma IGF-II level. Within a group of hypoinsulinaemic hypoglycaemia patients, a small number, invariably with evidence of a neoplasm, had low plasma IGF-I concentrations but apparently normal IGF-II levels. We propose that, in such cases, an apparently normal plasma IGF-II value is inappropriately high for the low plasma IGF-I level and, in association with non-ketotic hypoinsulinaemia and suppressed plasma growth hormone (GH), is diagnostic of a non-islet cell tumour as the cause of hypoglycaemia.

The effect of synthetic very low calorie diets on the GH-IGF-1 axis in obese subjects

IGF-1 concentrations were measured in plasma from 20 obese patients and 20 age- and sex-matched control subjects all of whom were fasting. Plasma IGF-1 concentrations were lower (p less than 0.05) in the obese individuals than in the controls. Plasma GH and insulin responses to stimulation with oral glucose were measured in 7 healthy normal weight individuals and both before and after energy restriction in 7 obese individuals. Before treatment the obese individuals were hyperinsulinaemic (fasting and integrated stimulated concentrations p less than 0.05) and showed attenuation of the plasma GH response to stimulation (peak and integrated stimulated values p less than 0.05 and less than 0.005, respectively) following oral glucose when compared to normal weight controls. Plasma insulin levels fell (both fasting and integrated concentrations p less than 0.05 and less than 0.005, respectively) and stimulated plasma GH responses increased (both peak and integrated values p less than 0.01 and less than 0.05, respectively) in the obese individuals following 3 wk treatment with a synthetic very low energy diet. Plasma IGF-1 concentrations remained unchanged during energy restriction. These results fail to support an endocrine IGF-1 mediated feedback inhibition on the hypothalamic-pituitary axis as the cause of the attenuated release of GH in obesity.

Insulin-like growth factor 1 in patients with hypoglycaemia

Plasma insulin-like growth factor 1 (IGF-1) concentrations were measured in a group of patients with hypoglycaemia due to endogenous hyperinsulinism, and compared with those in a group of patients matched for age and sex with hypoglycaemia and appropriately suppressed insulin levels. Insulin-like growth factor 1 concentrations were significantly higher in the hyperinsulinaemic hypoglycaemic group than in either the hypoinsulinaemic hypoglycaemia group or a group of euglycaemic control subjects. These data provide further evidence that insulin promotes IGF-1 production and release from the liver.

The effects of treatment with recombinant human growth hormone on body composition and metabolism in adults with growth hormone deficiency

In a double-blind, placebo-controlled trial, we studied the effects of six months of growth hormone replacement in 24 adults with growth hormone deficiency. Most of the patients had acquired growth hormone deficiency during adulthood as a consequence of treatment for pituitary tumors, and all were receiving appropriate thyroid, adrenal, and gonadal hormone replacement. The daily dose of recombinant human growth hormone (rhGH) was 0.07 U per kilogram of body weight, given subcutaneously at bedtime. The mean (+/- SE) plasma concentration of insulin-like growth factor I increased from 0.41 +/- 0.05 to 1.53 +/- 0.16 U per liter during rhGH treatment. Treatment with rhGH had no effect on body weight. The mean lean body mass, however, increased by 5.5 +/- 1.1 kg (P less than 0.0001), and the fat mass decreased by 5.7 +/- 0.9 kg (P less than 0.0001) in the group treated with growth hormone; neither changed significantly in the placebo group. The basal metabolic rate, measured at base line and after one and six months of rhGH administration, increased significantly; the respective values were 32.4 +/- 1.4, 37.2 +/- 2.2, and 34.4 +/- 1.6 kcal per kilogram of lean body mass per day (P less than 0.001 for both comparisons). Fasting plasma cholesterol levels were lower (P less than 0.05) in the rhGH-treated group than in the placebo group, whereas plasma triglyceride values were similar in the two groups throughout the study. We conclude that growth hormone has a role in the regulation of body composition in adults, probably through its anabolic and lipolytic actions.