Growth hormone treatment of growth hormone-deficient adults results in a marked increase in Lp(a) and HDL cholesterol concentrations

Long-term growth hormone excess induces marked alterations in lipoprotein metabolism in mice

The effects of long-term chronic growth hormone (GH) excess on lipid and lipoprotein metabolism were investigated in 8-mo-old bovine GH (bGH)-transgenic mice. Total body weight, serum cholesterol, insulin-like growth factor-I, and insulin levels were higher, whereas serum levels of glucose, free fatty acids, and triglycerides were lower in transgenic mice. Very low-density lipoprotein (VLDL) cholesterol levels were lower, and low-density lipoprotein (LDL) cholesterol levels were higher, in transgenic mice irrespective of gender, whereas only transgenic male mice had higher high-density lipoprotein cholesterol levels. Total serum apolipoprotein B (apoB) levels were not affected, but the amount of apoB in the LDL fraction was higher in transgenic mice. Hepatic LDL receptor expression was unchanged, whereas apoB mRNA editing and hepatic triglyceride secretion rate were reduced in bGH-transgenic male mice. Both lipoprotein lipase activity in adipose and heart tissue and beta-adrenergic-stimulated lipolysis were increased in transgenic male mice. The relative weight of adipose tissue was lower in transgenic mice, whereas hepatic triglyceride content was unchanged. Fat feeding of the mice equalized serum triglycerides and free fatty acids in bGH-transgenic and control mice. In summary, long-term GH excess is associated with marked alterations in lipid and lipoprotein metabolism, indicating decreased production and increased degradation of VLDL and preferential flux of fatty acids to muscle tissues.

Commencing growth hormone replacement in adults with a fixed low dose. Effects on serum lipoproteins, glucose metabolism, body composition, and cardiovascular function

The safety and effects of a fixed low dose of growth hormone (GH), 0.17 mg/day was evaluated for 3 months, on glucose metabolism, serum lipids, body composition and cardiac function in 53 GH deficient adults aged 18-78 years. Body composition was determined by dual energy X-ray absorptiometry and total body water was determined by bioelectrical impedance. Echocardiography was used to assess cardiac function and bicycle ergonometry was used to determine exercise capacity. All investigations were performed at baseline and after 3 months. At 3 months, serum levels of insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 and lipoprotein (a) and lean body mass were increased (P<0.05). Total and low density lipoprotein cholesterol levels and fat mass were reduced (P<0.05). There was an increase in the serum glucose value at 120 min after an oral glucose tolerance test performed at 3 months (P<0.05), no other changes in glucose metabolism or in cardiac function were noted. Side-effects were few and mild. This fixed low-dose regime resulted in improvements in body composition and lipid profile, without causing serious side effects. This is therefore a valid method to institute GH replacement in adults.

Diagnosis and management of growth hormone deficiency in adults

In adults, GHD is a clinical syndrome that occurs in patients with pituitary or hypothalamic disease. It may be asymptomatic or present with relatively nonspecific constitutional symptoms. Most patients have abnormal body composition, consisting of increased fat mass and decreased lean mass. Life expectancy is significantly decreased in hypopituitary patients with GHD, with cardiovascular disease a common cause of death. Treatment with growth hormone reverses abnormalities in body composition and may reduce cardiovascular risk factors; however, the long-term treatment outcomes regarding mortality, the incidence of cardiovascular disease, bone fractures, tumor development, and recurrence are not known. Longer prospective clinical studies are needed. The major manufacturers of growth hormone have initiated postmarketing surveillance databases to monitor the safety of growth hormone treatment.

Coronary risk in growth hormone deficient hypopituitary adults: increased predicted risk is due largely to lipid profile abnormalities

BACKGROUND

Hypopituitarism in adults is associated with increased vascular mortality, which has been attributed to GH deficiency.

OBJECTIVE

To compare the lipid profile and coronary risk predicted by the Framingham Heart Study equation in GH-deficient hypopituitary patients and healthy age and gender-matched controls.

DESIGN

A cross-sectional observational study.

METHODS

We studied 50 adult-onset growth hormone deficient hypopituitary patients (23F, 27M), on appropriate conventional hormone replacement and 45 controls (22F, 23M) matched for age, gender and smoking habit. The subjects (age range 30-75 years) were free from diabetes, hypertension, ischaemic heart disease (IHD) and peripheral vascular disease. All hypogonadal male patients were on testosterone replacement therapy. A similar proportion of female patients (8/23) and controls (7/22) were on HRT. Body mass index (BMI), waist-hip ratio (WHR) and blood pressure were recorded. After an overnight fast blood glucose, total-cholesterol, triglycerides, HDL-cholesterol, apolipoproteins A-I, B and Lp (a) were measured. Coronary risk was calculated for each individual from age, gender, systolic blood pressure, total and HDL cholesterol, smoking habit and presence of diabetes and left ventricular hypertrophy using the Framingham equation.

RESULTS

BMI and WHR were significantly increased in GHD hypopituitary adults of both sexes, but to a greater extent in females. Triglycerides were elevated in both sexes. Total and LDL-cholesterol were increased in both sexes (significantly only in males), and HDL cholesterol and apo A-I were lower (significantly only in females). The reduction in HDL cholesterol was correlated negatively with adiposity (BMI), particularly when centrally distributed (WHR) in patients and controls. LDL cholesterol did not correlate to adiposity but higher levels were present in GH-deficient subjects. The total to HDL cholesterol ratio was significantly increased in patients of both genders (P = 0.002). There were no differences in the apolipoproteins B and Lp(a) between patients and controls. Absolute risk (mean +/- SEM) of a fatal or non-fatal coronary event during the next 5 years was significantly greater in GHD hypopituitary patients than control subjects (4.82 +/- 0.73% vs. 2.94 +/- 0.53, P = 0.04). Cardiovascular risk relative to the local population (RR) was significantly higher in GHD hypopituitary adults (RR = 1.43 CL 1.06-1.80, P = 0.011) but not in the control group (1.08 CL 0.59-1.6). When divided by gender, RR for male patients was not increased (1.14 CL 0.83-1.45, P = 0.096). However, female patients had significantly higher RR (1.7 CL 1.05-2.5, P = 0.048). The RR for male and female controls was not different from the local population.

CONCLUSION

Changes in lipid levels help to explain the results from risk factor modelling which show increased coronary risk in growth hormone deficient hypopituitary patients, particularly females. The abnormal lipid profile is characterized in both genders by an increase in the total to HDL ratio [corrected], an important parameter in the Framingham equation. The lipid abnormalities conferring increased risk is related to growth hormone deficiency either directly (LDL) or indirectly through increased central obesity (HDL) [corrected]. Adverse calculated coronary risk might provide a new objective indication for consideration of GH replacement therapy in adults.

Growth hormone reduces plasma cholesterol in LDL receptor-deficient mice

Growth hormone (GH) has pleiotropic effects on cholesterol and lipoprotein metabolism. Pituitary GH is important for the normal regulation of hepatic LDL receptors (LDLR), for the enzymatic activity of bile acid regulatory cholesterol 7alpha-hydroxylase (C7alphaOH), and for the maintenance of resistance to dietary cholesterol. The present study aimed to determine whether GH has beneficial effects on plasma lipids and hepatic cholesterol metabolism in mice devoid of LDLR. Compared with wild-type controls, LDLR-deficient mice had approximately 250% elevated plasma total cholesterol and approximately 50% increased hepatic cholesterol levels; hepatic HMG CoA reductase activity was reduced by 70%, whereas C7alphaOH activity was increased by 40%. In LDLR mice, GH infusion reduced plasma cholesterol and triglycerides up to 40%, whereas HMG CoA reductase and C7alphaOH activities were stimulated by approximately 50% and 110% respectively. GH also stimulated HMG CoA reductase and C7alphaOH activities in control mice, whereas hepatic LDLR and plasma lipoproteins were unchanged. The effects of cholestyramine and atorvastatin on C7alphaOH in LDLR-deficient mice were potentiated by GH, and this was associated with a further reduction in plasma cholesterol. GH treatment reduces plasma cholesterol and triglycerides and stimulates C7alphaOH activity in mice devoid of LDLR, particularly in combination with resin or statin treatment. The potential of GH therapy in patients with homozygous familial hypercholesterolemia should be evaluated.

Growth hormone: a promising treatment for the failing heart?

Many pathologic processes that accelerate the progression of heart failure, such as cardiac remodeling and impaired contractility, may be modulated by administration of recombinant growth hormone. The agent improves structural and functional aspects of the failing heart both in the short term and after several months of therapy. However, conflicting clinical results cast doubt on whether it has a clear benefit in all of these patients. In addition, growth hormone therapy may be associated with cardiac and noncardiac adverse effects. Many questions must be addressed before its place in heart failure therapy is established. Optimal patient population, dosing regimen, duration of therapy, and effect on patient survival are unknown. Until larger, blinded studies are completed, growth hormone therapy remains an investigational approach to managing refractory heart failure.

Effects of normalization of GH hypersecretion on lipoprotein(a) and other lipoprotein serum levels in acromegaly

BACKGROUND & AIMS

Lipoprotein(a) has been recognized as an important risk factor for cardiovascular disease. Lipoprotein(a) has been found to be elevated in sera of acromegalic patients, possibly contributing to the increased incidence of coronary heart disease found in these patients. In the present study we sought to determine the effects of GH hormonal status on lipoprotein(a) and other lipid parameters, including lipoprotein lipase (LPL) activity.

DESIGN

Cross-sectional study.

PATIENTS

Twenty acromegalic patients, with either active (n = 12) or controlled (n = 8) acromegaly, were studied. Twenty-nine healthy subjects served as control group for serum lipid measurements.

MEASUREMENTS

Serum GH, IGF-1, IGF binding protein-3 (IGFBP-3) and insulin levels were measured in patients. Insulin resistance was measured by the homeostatic model assessment (HOMA). Plasma total cholesterol, triglycerides, HDL-lipids, apolipoproteins A-I and B, lipoprotein(a) and lipoprotein lipase activity were also measured.

RESULTS

The highest lipoprotein(a) levels were observed in patients with active acromegaly, followed by patients with controlled acromegaly, whose lipoprotein(a) concentrations were still significantly higher than those of the control group (means +/- SEM: active acromegaly, 0.67+/-0.13 g/l; controlled acromegaly, 0.41+/-0.12 g/l; controls 0.17+/-0.02 g/l; P<0.05). There were no differences in other lipid and lipoprotein values among the groups. In patients, significant correlations were observed between lipoprotein(a) and basal GH levels (r = 0.56, P<0.02), mean GH levels (r = 0.48, P<0.05) and with insulin resistance estimated by HOMA (r = 0.62, P<0.01). No correlations were found between lipoprotein(a) and IGF-1 or IGFBP-3 levels.

CONCLUSIONS

Our present results demonstrate that both active acromegalic patients and those with controlled disease have elevated serum lipoprotein(a) concentrations. The findings might suggest that the present biochemical criteria for cure of acromegaly are not strict enough to result in the normalization of all the undesirable metabolic changes found in this disease, and also that significant cardiovascular risk may persist despite successful treatment of acromegaly.

Lipoprotein Lp(a) and atherothrombotic disease

High plasma concentrations of lipoprotein (a) [Lp(a)] are now considered a major risk factor for atherosclerosis and cardiovascular disease. This effect of Lp(a) may be related to its composite structure, a plasminogen-like inactive serine-proteinase, apoprotein (a) [apo(a)], which is disulfide-linked to the apoprotein B100 of an atherogenic low-density lipoprotein (LDL) particle. Apo(a) contains, in addition to the protease region and a copy of kringle 5 of plasminogen, a variable number of copies of plasminogen-like kringle 4, giving rise to a series of isoforms. This structural homology endows Lp(a) with the capacity to bind to fibrin and to membrane proteins of endothelial cells and monocytes, and thereby inhibits binding of plasminogen and plasmin formation. This mechanism favors fibrin and cholesterol deposition at sites of vascular injury and impairs activation of transforming growth factor-beta (TGF-beta) that may result in migration and proliferation of smooth muscle cells into the vascular intima. It is currently accepted that this effect of Lp(a) is linked to its concentration in plasma, and an inverse relationship between apo(a) isoform size and Lp(a) concentrations that is under genetic control has been documented. Recently, it has been shown that inhibition of plasminogen binding to fibrin by apo(a) from homozygous subjects is also inversely associated with isoform size. These findings suggest that the structural polymorphism of apo(a) is not only inversely related to the plasma concentration of Lp(a), but also to a functional heterogeneity of apo(a) isoforms. Based on these pathophysiological findings, it can be proposed that the predictive value of Lp(a) as a risk factor for vascular occlusive disease in heterozygous subjects would depend on the relative concentration of the isoform with the highest affinity for fibrin.

A nine-month, placebo-controlled study of the effects of growth hormone treatment on lipoproteins and LDL size in abdominally obese men

Abdominal/visceral obesity is associated with blunted growth hormone (GH) secretion and an unfavourable lipoprotein pattern. In this study, the effect of GH treatment on LDL size and on serum lipoprotein concentrations was determined in abdominally obese men. Thirty men, aged 48-66 years, with a body mass index (BMI) of 25-35 kg/m(2)and a waist:hip ratio of >0.95, received treatment with GH (9. 5 microg/kg/day) or placebo for 9 months. Serum concentrations of total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C) and apolipoprotein B (apoB) were reduced (P<0.05, P<0.05 and P<0.001 vs placebo, respectively). Serum lipoprotein(a) [Lp(a)] concentration increased (P<0.05 vs. placebo). Mean low density lipoprotein (LDL) particle diameter was marginally increased by active treatment as compared with placebo (P =0.08). No changes were observed in the serum concentrations of high density lipoprotein-cholesterol (HDL-C), apolipoprotein A-I (apoA-I) and apolipoprotein E (apoE). In conclusion, 9 months of GH treatment in abdominally obese men beneficially reduced serum concentrations of TC, LDL-C and apoB, and marginally increased mean LDL diameter, while serum Lp(a) increased. The ultimate effect of GH therapy on the cardiovascular risk remains, however, to be determined.

Continuation of growth hormone (GH) replacement in GH-deficient patients during transition from childhood to adulthood: a two-year placebo-controlled study

Previous studies have demonstrated beneficial effects of GH replacement, in adults with GH deficiency (GHD), on body composition, physical fitness, and quality of life. These studies, however, concern patients with adult-onset GHD or childhood-onset (CO) patients enrolled several years after withdrawal of initial therapy. So far, the effects of continuation of GH-administration in patients with CO-GHD have not been examined. We studied a group of nineteen young adults (13 males + 6 females; 16-26 yr old; mean age, 20.2 +/- 0.65 yr) with CO-GHD, in a randomized, parallel, double-blind, placebo-controlled trial for 1 yr, followed by an open phase with GH for 1 yr. All patients received GH therapy at the start of study, and trial medication (GH/placebo) was given in a similar dose. Patients randomized to continued GH treatment exhibited no significant changes in any parameters tested, but intra- and interindividual variations in insulin-like growth factor (IGF)-I levels could suggest compliance problems. Discontinuation of GH for 1 yr resulted in a decrease in serum IGF-I, from 422.0 +/- 56.8 to 147.8 +/- 33.4 microg/L, in the placebo group (P = 0.003). After discontinuation of GH for 1 yr, an increase in total body fat (TBF, kg), measured by dual-energy x-ray absorptiometry scan, was seen [placebo: 22.7 +/- 2.7 to 26.5 +/- 2.5 (P = 0.01); GH: 16.2 +/- 2.1 to 17.2 +/- 2.1 (not significant)]. Resumption of GH after placebo was followed by increments in serum IGF-I (microg/L) [from 147.8 +/- 33.4 to 452 +/- 76 (P = 0.001)] and IGF-binding protein 3, as well as in fasting glucose (mmol/L) [4.9 +/- 0.2 vs. 5.3 +/- 0.2 (P = 0.03)]. After resumption of GH lean body mass (kg) increased [52.4 +/- 4.9 vs. 60.7 +/- 5.6 (P = 0.006)]. Likewise, resumption of GH therapy increased thigh muscle volume and thigh muscle/fat ratio, as assessed by computed tomography [muscle volume (cm2/10 mm): 118.2 +/- 11.7 vs. 130.0 +/- 10.9 (P = 0.002); muscle/fat ratio: 1.33 +/- 0.24 vs. 1.69 +/- 0.36 (P = 0.02)]. In conclusion, discontinuation of GH treatment in GHD patients, during the transition from childhood to adulthood, induces significant and potentially unfavorable changes in IGF-I and body composition, both of which are reversed after resumption of GH treatment. By contrast, continuation of GH therapy results in unaltered IGF-I and body composition. We recommend continuation of GH therapy in these patients, to be undertaken in collaboration between pediatricians and adult endocrinologists.

Effects of growth hormone treatment on very-low density lipoprotein apolipoprotein B100 turnover in adult hypopituitarism

Adult hypopituitarism is associated with hyperlipidemia, mainly due to an increase of very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels. Recent studies have shown that such patients exhibit increased hepatic secretion of VLDL apolipoprotein B100 (VLDL apo B100). To examine the effects of growth hormone (GH) replacement on VLDL apo B100 turnover, 13 GH-deficient hypopituitary patients (8 women and 5 men; aged 47 +/- 3 years, mean +/- SEM; body mass index [BMI], 30 +/- 2 kg/m2) entered a double-blind placebo-controlled study for 6 months (GH 0.125 IU/kg/wk for 4 weeks, and then 0.25 IU/kg/wk). GH was subsequently used in all patients for a further 6 months. A 6-hour [1-13C] leucine infusion was administered at baseline and at 6 months. The secretion rate of VLDL apo B100 was derived by kinetic analysis following quantitation of isotopic enrichment by gas chromatography/mass spectrometry. The GH-treated group (6 patients) demonstrated a similar fractional secretion rate (FSR) for VLDL apo B100 at 0 and 6 months. The pool size and absolute secretion rate (ASR) also were unaffected significantly by GH therapy. No significant changes were observed in the placebo group (7 patients). Treatment with GH for 6 months caused an increase in the high-density lipoprotein (HDL) cholesterol concentration (13 patients, 1.27 +/- 0.13 v 1.16 +/- 0.10 mmol/L, respectively, P = .05), whereas total cholesterol and triglyceride concentrations did not change. Nonesterified fatty acids (NEFAs) increased during GH therapy (471 +/- 43 micromol/L at 6 months v 349 +/- 49 micromol/L at baseline, P < .0005). The data suggest that GH does not affect VLDL apo B100 turnover in a significant way.

Effects of growth hormone replacement therapy on lipids, lipoproteins and apolipoproteins: is the increased apolipoprotein A-1/B ratio the only benefit?

BACKGROUND

The aim of the present study was to investigate the controversial role of growth hormone (GH) therapy in lipid regulation.

METHODS

We studied serum levels of cholesterol and subgroups, triglyceride and apolipoprotein A-1 and B in 41 GH-deficient children (with subgroups of untreated and short- and long-term treated subjects) and 20 healthy controls.

RESULTS

Cholesterol and low-density lipoprotein cholesterol levels (in mmol/L) were found to be 4.92 +/- 1.34 and 3.02 +/- 1.58 in untreated, 4.15 +/- 0.72 and 2.46 +/- 0.65 in short-term (3 month) treated, 4.93 +/- 1.39 and 3.15 +/- 1.38 in long-term (> 1 year) treated and 4.11 +/- 0.5 and 2.0 +/- 0.74 in control subjects, respectively. The apolipoprotein A-1:B ratio was 1.98 +/- 0.5 in long-term treated and 1.6 +/- 0.6 in control subjects.

CONCLUSIONS

The improvement of lipid composition with short-term GH therapy is temporary, but the increase in apo A-1:B is not and seems to be the particular benefit of this therapy.

Treatment of growth hormone deficiency in adults

In analogy with other hormonal replacement therapy GH treatment should be commenced with a low starting dose, independent of body weight or body surface area. Hormonal replacement should mimic the normal physiology to minimize the risk of side effects in the life-long replacement of adults. We should, therefore, consider individual responsiveness and also be aware of the difference between pattern of GH under normal condition and during s.c. administration. The safety and monitoring of GH replacement therapy in adults have been addressed in the Growth Hormone Research Society Consensus Guidelines for Diagnosis and Treatment of Adults with GH Deficiency from the Port Stephens Workshop, April 1997. Besides finding better and more accurate biochemical markers for choosing correct GH replacement dose, future research should address the long-term benefits and safety with GH replacement in adults, with special emphasize on incipient risks in terms of cardiovascular disease and of neoplasia, in particular.

Endocrine and lipid effects of oral L-arginine treatment in healthy postmenopausal women

As a substrate for nitric oxide synthesis, L-arginine may give the same protection as estrogen, but its other biologic effects may adversely affect atherogenesis. Therefore, possible endocrine and lipid effects of L-arginine were investigated in a double-blind, placebo-controlled, single crossover study. After randomization, oral L-arginine (9 g) or placebo was given daily for 1 month, with crossover to the alternate therapy after a 1-month washout period, to 10 postmenopausal women receiving no estrogen. Compared with placebo, L-arginine increased growth hormone (1.5+/-1.8 mg/L vs. 0.6+/-0.6 mg/L, P = .04) but had no effect on insulin and catecholamines. Total cholesterol, triglyceride, apolipoprotein E, and low-, very-low-, and high-density lipoprotein cholesterol levels were also unaffected. Lipoprotein(a) measured by an immunoturbidimetric method was increased by L-arginine in 9 of 10 women relative to placebo (0.46+/-0.35 g/L vs. 0.38+/-0.30 g/L, P = .053), and the changes in lipoprotein(a) levels significantly correlated with the relative increase in growth hormone (r = 0.85, P = .03). However, lipoprotein(a) measured by an enzyme-linked immunosorbent assay failed to demonstrate significant changes. Lack of an increase by L-arginine in lipoprotein(a) with a verifiable apolipoprotein(a) isoform-independent method, despite an increase in growth hormone, questions the validity of previous observations for growth hormone-induced increases in lipoprotein(a). The observed lack of effect on major endocrine hormones and lipid profile support the safety of oral L-arginine administration.

Changes in lipoprotein(a) levels measured by six kit methods during growth hormone treatment of growth hormone-deficient adults

Lipoprotein(a) [Lp(a)], an independent risk factor for cardiovascular disease, has previously been reported to increase, decrease or show no change in growth hormone (GH)-deficient individuals receiving GH replacement. To assess whether these inconsistencies could be attributed to differences in immunoassay methods, Lp(a) was measured by six commercial kits at 0, 3, 6 and 9 months in nine GH-deficient individuals (median age 68.3 years, six male) during 9 months GH therapy. There was a significant rise in Lp(a) with the INCStar immunoturbidimetric (IT) method and the Mercodia enzyme linked immunosorbent assay (ELISA) (P</=0.05, two-tailed Wilcoxon signed rank test), a non-significant rise with the Pharmacia immuno-radiometric assay and the Biopool ELISA methods (P =0.06), and no change with the Immuno ELISA and WAKO IT kits. There was also considerable variation in the values reported within each individual. These results suggest that the previously reported inconsistencies may in part be due to methodological differences, and that the effect of GH on Lp(a) remains unknown. This study highlights the need for a more common approach to the standardization of Lp(a) methods and the selection of antibodies used in them. Better performing methods may allow a more reliable interpretation of the effects of GH on Lp(a)

Interrelationships of spontaneous growth hormone axis activity, body fat, and serum lipids in healthy elderly women and men

Aging is associated with decreased growth hormone (GH) secretion and plasma insulin-like growth factor-I (IGF-I) levels, increased total and abdominal fat, total and low-density lipoprotein (LDL) cholesterol, and triglycerides, and reduced high-density lipoprotein (HDL) cholesterol. Similar changes in lipids and body composition occur in nonelderly GH-deficient adults and are reversed with GH administration. To examine whether GH/IGF-I axis function in the elderly is related to the lipid profile independently of body fat, we evaluated GH secretion, serum IGF-I and IGF binding protein-3 (IGFBP-3) levels, adiposity via the body mass index (BMI), waist to hip ratio (WHR), dual-energy x-ray absorptiometry (DEXA), and magnetic resonance imaging (MRI), and circulating lipids in 101 healthy subjects older than 65 years. Integrated nocturnal GH secretion (log IAUPGH) was inversely related (P < .005) to DEXA total and abdominal fat and MRI visceral fat in both genders. Log IAUPGH was inversely related to visceral fat in women (P < .005) and men (P < .0001), but was not significantly related to total fat in either gender. In women, log IAUPGH was related inversely to total and LDL cholesterol and positively to HDL cholesterol (P < .008). In men, log IAUPGH was inversely related to total cholesterol and triglycerides (P < .005). In women, HDL cholesterol was inversely related to the WHR (P < .005). In men, triglycerides were positively related (P < .001) to the WHR and DEXA abdominal and MRI visceral fat. Multivariate regression revealed log IAUPGH, but not DEXA total body fat, to be an independent determinant of total (P < .001 for women and P = .01 for men) and LDL (P < .007 and P = .05) cholesterol in both sexes and of HDL cholesterol (P < .005) and triglycerides (P < .03) in women. Log IAUPGH, but not DEXA abdominal fat, was related to total (P < .005 and P < .03) and LDL (P < .03 and P = .05) cholesterol in both genders and to HDL in women (P < .05). Log IAUPGH, but not MRI visceral fat, was related to total cholesterol (P < .03 and P = .05) in women and men. Age, IGF-I, and IGFBP-3 were not significantly related to any body fat or lipid measures, except for a positive correlation of IGF-I with triglycerides in men. Thus, endogenous nocturnal GH secretion predicts total, LDL, and HDL cholesterol levels independently of total or abdominal fat, suggesting that it is an independent cardiometabolic risk factor in healthy elderly people.

No relationship between serum lipoprotein(a) and albumin concentrations in patients with acute phase response

The aim of this study was to investigate the relationship between lipoprotein(a) [Lp(a)] and albumin concentrations in the serum of patients with acute phase response (APR). We have compared the Lp(a) concentrations and apolipoprotein [apo(a)] phenotypes of 40 controls with those of 40 APR patients with normoalbuminaemia and 40 APR patients with hypoalbuminaemia. We have also compared concentrations of haptoglobin (Hp) and alpha 1-antitrypsin (AAT) containing a high sialic acid content, similar to Lp(a). The mean serum Lp(a) concentration (SD) of the 40 controls was 0.190 (0.142) g/L. The mean serum Lp(a) concentration was 0.358 (0.257) g/L (P < 0.001) in 80 APR patients. However, there was no difference in serum Lp(a) concentrations between the APR patients with hypoalbuminaemia [0.353 (0.268) g/L] and the APR patients with normoalbuminaemia [0.362 (0.249) g/L]. No significant difference was found in the distributions of apo(a) phenotypes between the controls, the APR patients with hypoalbuminaemia, and the APR patients with normoalbuminaemia (P = 0.183). In the APR patients, the serum concentrations of AAT and Hp were respectively 2.709 (0.822) g/L and 2.631 (1.340) g/L, whereas those of normal controls were respectively 1.422 (0.219) g/L (P < 0.001) and 0.956 (0.442) g/L (P < 0.001). In conclusion, the Lp(a) is one of the acute phase reactants whose synthesis concurrently increases with other APRs, especially those with a high sialic acid content. The increase of the serum Lp(a) concentrations in the APR patients is not related to serum albumin concentration.

The relation between bone mineral density, insulin-like growth factor I, lipoprotein (a), body composition, and muscle strength in adolescent males

Osteoporosis is the most common metabolic bone disease. A low peak bone mass is regarded a risk factor for osteoporosis. Heredity, physical activity, and nutrition are regarded important measures for the observed variance in peak bone mass. Lp(a) lipoprotein is a well-known risk factor for atherosclerosis. Serum insulin-like growth factor I (IGF-I) has been found to be increased in males with early cardiovascular disease. In this study, we evaluated the association between bone mass, body constitution, muscle strength, Lp(a), and IGF-I in 47 Caucasian male adolescents (mean age, 16.9 yr). Bone mineral density (BMD) and body composition were measured by dual x-ray absorptiometry, muscle strength of thigh using an isokinetic dynamometer, IGF-I by RIA, and Lp(a) by enzyme-linked immunosorbent assay. IGF-I was only associated with Lp(a) (r = 0.38, P < 0.01). Lp(a) was related to total body (r = 0.40, P < 0.01), skull (r = 0.45, P < 0.01), and femoral neck BMD (r = 0.44, P < 0.01). Lp(a) was also related to fat mass (r = 0.34, P < 0.05) and muscle strength (r = 0.30-0.42, P < 0.05). After multiple regression and principal component (PC) analysis, the so-called PC body size (weight, fat mass, lean body mass, and muscle strength) was the most significant predictor of BMD (beta = 0.28-0.51, P < 0.05-0.01), followed by the so-called PC physical activity (beta = 0.28-0.38, P < 0.05-0.01, weight-bearing locations). However, the PC analysis confirmed that Lp(a) was an independent predictor of total body, skull, and femoral neck BMD (beta = 0.33-0.36, P < 0.01). The present investigation confirms that BMD, body size, and muscle strength are closely related and that the level of physical activity is a major determinant of BMD. However, the positive relation of Lp(a), a major risk factor for cardiovascular disease, to BMD has not previously been described. The importance of this observation has to be further investigated.

The effects of 10 years of recombinant human growth hormone (GH) in adult GH-deficient patients

The long term effects of GH replacement in adult GH-deficient (GHD) patients have not yet been clarified. We studied 21 GHD adults who originally took part in a randomized, double blind, placebo-controlled trial of GH treatment in 1987. After completion of that trial, 10 patients received continuous GH replacement for the subsequent 10 yr, whereas 11 did not. A group of 11 age- and sex-matched normal controls were also studied in 1987 and 1997. Lean body mass, as assessed by total body potassium measurement and computed tomography scanning of the dominant thigh, increased in the GH-treated group (P < 0.01 for both) only (P < 0.05 between groups for total body potassium). Low density lipoprotein cholesterol decreased in the GH-treated group (P < 0.05) only. Carotid intima media thickness was significantly greater (P < 0.05) in the untreated group than in the GH-treated group. Assessment of psychological well-being using the Nottingham Health Profile revealed improvement in overall score, energy levels, and emotional reaction in the GH-treated group compared with those in the untreated group (P < 0.02). In conclusion, GH treatment for 10 yr in GHD adults resulted in increased lean body and muscle mass, a less atherogenic lipid profile, reduced carotid intima media thickness, and improved psychological well-being.

Treatment of obese subjects with the oral growth hormone secretagogue MK-677 affects serum concentrations of several lipoproteins, but not lipoprotein(a)

Obesity is associated with blunted GH secretion and an unfavorable lipoprotein pattern. The objective of this study was to investigate the effects of treatment with the oral GH secretagogue MK-677 on lipoproteins in otherwise healthy obese males. The study was randomized, double blind, and parallel. Twenty-four obese males, aged 18-50 yr, with body mass index greater than 30 kg/m2 and waist/hip ratio above 0.95 were treated with 25 mg MK-677 (n = 12) or placebo (n = 12) daily for 8 weeks. MK-677 treatment did not significantly change serum lipoprotein(a) [Lp(a)] levels. Serum apolipoprotein A-I and E (apoA-I and apoE) were increased at 2 weeks (P < 0.001 and P < 0.01 vs. placebo, respectively), but were not changed at study end. Serum total cholesterol and low density lipoprotein (LDL) cholesterol (LDL-C) levels were not significantly changed by MK-677 treatment. Serum high density lipoprotein (HDL) cholesterol (HDL-C) was increased at 2 weeks of MK-677 treatment (P < 0.01 vs. placebo), but not at 8 weeks. The LDL-C/HDL-C ratio was reduced after 8 weeks of MK-677 treatment (P < 0.05 vs. placebo). Mean LDL particle diameter was decreased at 2 weeks (P < 0.05 vs. placebo), but was unchanged compared with baseline values at 8 weeks (P = NS vs. placebo). The level of serum triglycerides was increased at 2 (P < 0.05 vs. placebo), but not at 8, weeks. Lipoprotein lipase activity in abdominal and gluteal sc adipose tissue was not affected by active treatment. In conclusion, treatment with the oral GH secretagogue MK-677 affected circulating lipoproteins. The effects on serum apoA-1, apoE, triglycerides, and mean LDL particle diameter were transient. At study end, the LDL-C/HDL-C ratio was decreased. MK-677 treatment did not significantly affect serum Lp(a) concentrations at the present dose and administration protocol.

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.

Gender difference in the response of growth hormone (GH)-deficient adults to GH therapy

While individual hypopituitary patients undoubtedly benefit from growth hormone (GH) therapy, there is considerable variability in the response to treatment. Given the expense, possible lack of benefit, and potential risks associated with long-term therapy, we sought to identify characteristics potentially associated with a favorable response to GH replacement. Twelve GH-deficient adults (seven men and five women aged 35.4+/-2.5 years, mean +/- SEM) participated in a 12-month open study of GH replacement (0.125 IU/kg/wk for 4 weeks and 0.25 IU/kg/wk thereafter) designed to examine the impact of GH on body composition, lipid profile, and psychological well-being. Using bioelectrical impedance analysis (BIA), there was a reduction in body fat (BF) and an increase in lean body mass (LBM) and total body water (TBW) (P < .05) following 12 months of GH treatment. In addition, there was a significant improvement in psychological well-being as indicated by a decrease in the Nottingham Health Profile (NHP) score (P < .05) and a decrease in both total cholesterol (P = .005) and low-density lipoprotein (LDL) cholesterol (P < .03). GH therapy was associated with an increase in fasting plasma glucose (P = .008) and hemoglobin A1c (HbA1c (P = .06). When analyzed by gender, the beneficial effect of GH was greater in men versus women for the increment in insulin-like growth factor-1 ([IGF-1] 375+/-59 v 148+/-73 microg/L, mean +/- SEM), increase in LBM (6.8+/-2.5 v -0.06+/-1.6 kg), reduction in BF (5.6+/-1.6 v 1.0+/-1.9 kg), and increase in TBW (5.0+/-1.6 v 0.14+/-1.29 L) (P < .05). HbA1c increased significantly in women (P < .05). The beneficial effect of GH tended to be greatest in those with the most significant abnormality in baseline values (P < .05). The duration of hypopituitarism showed an indirect correlation with the change in total cholesterol (P < .005). Baseline IGF-1 levels correlated directly with changes in TBW (P < .05). These data indicate that men with GH deficiency appear more responsive to GH therapy than women with respect to the increase in IGF-1 levels and improvement in body composition. In general, patients with the most significant abnormality in baseline values, the highest IGF-1 levels, and the shortest duration of hypopituitarism respond best. With long-term GH therapy, careful monitoring of glucose tolerance is indicated.

Atherothrombogenicity of lipoprotein(a): the debate

Although lipoprotein(a) (Lp[a]) has been recognized as an atherothrombogenic factor, the underlying mechanisms for this pathogenicity have not been clearly defined. Plasma levels have received most of the attention in this regard; however, discrepancies among population studies have surfaced. Particularly limited is the information on the fate of Lp(a) that enters the arterial wall, in terms of mechanisms of endothelial transport and interactions with cells and macromolecules of the extracellular matrix. A typical Lp(a) represents a low-density lipoprotein (LDL)-like particle having as a protein moiety apo B-100 linked by a single interchain disulfide bond to a unique multikringle glycoprotein, called apolipoprotein(a) (apo[a]). In vitro studies have shown that Lp(a) can be dissected into its constituents, LDL and apo(a). In turn, the latter can be cleaved by enzymes of the elastase and metalloproteinase families into fragments that exhibit a differential behavior in terms of binding to macromolecules of the extracellular matrix: fibrinogen, fibronectin, and proteoglycans. By immunochemical criteria, apo(a) predominantly localizes in areas of human arteries affected by the atherosclerotic process, where elastase and metalloproteinase enzymes operate and where apo(a) fragments are potentially generated. The accumulation of these fragments in the vessel wall is likely to depend on their affinity for the constituents of the extracellular matrix. Thus, factors that modulate inflammation and inflammation-mediated fragmentation of Lp(a)/apo(a) may play an important role in the cardiovascular pathogenicity of Lp(a). This pathogenicity may be attenuated by measures directed at preventing the activation of those vascular cells that secrete enzymes with a proteolytic potential for Lp(a)/apo(a), namely, leukocytes, macrophages, and T cells.

HDL-cholesterol reductions associated with adult growth hormone replacement

OBJECTIVE

To study the effects of human growth hormone (hGH) replacement on serum lipids and lipoprotein (a) (Lp(a)) concentrations.

DESIGN

A randomized double blind placebo controlled trial for 6 months followed by an open trial where all patients were treated with hGH for a further 6 months. Treatment was with recombinant hGH given in a dose of 0.125U/kg/wk increasing to 0.25U/Kg/wk.

PATIENTS

Thirty two patients with growth hormone deficiency were recruited, but two withdrew because of side effects. Of the thirty patients (age 35.1 +/- 11.8 year; mean +/- SD) completing the study 13 of were assigned to the placebo group for six months and 17 to active treatment from the start.

MEASUREMENTS

Fasting serum samples were analysed for total cholesterol, High density lipoprotein (HDL)-cholesterol, HDL-subfractions, triglycerides, lipoprotein (a) (Lp(a)) and IGF-1. LDL-cholesterol was calculated using the Friedewald formula.

RESULTS

Compared to placebo, 6 months treatment with hGH therapy resulted in increased IGF-1 (37.6 +/- 4.1 vs. 14.0 +/- 2.2 nmol/l, P < 0.01), but there was no significant difference in any of the lipid parameters measured between placebo and active treatment groups at 6 months. hGH was associated with a decrease in HDL-cholesterol concentration from baseline to 6 months (0.97 +/- 0.08 to 0.76 +/- 0.10 mmol/l P < 0.01), especially within the HDL2 subfraction. This reduction was maintained at 12 months. There was no change in Lp(a) concentrations from 0 to 6 months (placebo -26 (-340 to 82), median and range, active -4 (-586 to 212) mg/l). There was no change in total cholesterol, LDL-cholesterol, triglycerides or proportion of HDL subfractions.

CONCLUSIONS

Treatment with hGH can reduce serum HDL-cholesterol concentrations. Further investigation of this is required.

Effect of thyroid hormone replacement on lipoprotein(a), lipids, and apolipoproteins in subjects with hypothyroidism

OBJECTIVE

To study the effect of thyroid hormone replacement on total cholesterol, low-density lipoprotein cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-I and B-100, and lipoprotein(a) [Lp(a)] in subjects with hypothyroidism.

MATERIAL AND METHODS

In 17 patients with clinical primary hypothyroidism, studies were done before and after thyroid hormone replacement therapy. Free thyroxine and thyrotropin were determined by chemiluminescent assay. Total cholesterol and triglycerides were measured by enzymatic methods, and HDL-C was measured after dextran sulfate-MgCl2 precipitation. Apolipoprotein A-I and B-100 were assayed by immunonephelometry. For measurement of Lp(a), we used a sequential sandwich enzyme-linked immunosorbent assay.

RESULTS

After levothyroxine treatment, the mean concentration of thyrotropin decreased from 91.4 to 3.7 microIU/mL, and free thyroxine increased from 0.5 to 1.2 ng/ dL. Total cholesterol, triglycerides, HDL-C, low-density lipoprotein cholesterol, and apolipoprotein A-I and B-100 decreased after thyroid hormone replacement therapy. Lp(a) levels also decreased significantly (P<0.05) after treatment, from a mean of 33.4 to 25.6 mg/dL.

CONCLUSION

Hypothyroidism is associated with an increase in total cholesterol, triglycerides, HDL-C, apolipoprotein A-I and B-100, and Lp(a). A reduction in lipid and lipoprotein levels after thyroid hormone replacement in our study cohort resulted in a less atherogenic profile.

Growth hormone deficiency and cardiovascular risk

It is now recognized that growth hormone (GH) deficiency in adults represents a distinct clinical syndrome that encompasses reduced psychological well-being as well as specific metabolic abnormalities. The latter features, which include hypertension, central obesity, insulin resistance, dyslipidaemia and coagulopathy, closely resemble those of metabolic insulin resistance syndrome. The increased cardiovascular morbidity and mortality demonstrated in these GH-deficient (GHD) adults reinforce the close association between the two syndromes. Replacement of GH in GHD adults has resulted in a marked reduction of central obesity and significant reduction in total cholesterol but little change in other risk factors, in particular insulin resistance and dyslipidaemia. The persistent insulin resistance and dyslipidaemia, together with the elevation of plasma insulin levels and lipoprotein (a) with GH replacement in these subjects are of concern. Long-term follow-up data are required to assess the impact of GH replacement on the cardiovascular morbidity and mortality of GHD adults. Further exploration of the appropriateness of the GH dosage regimens currently being employed is also indicated.

Dyslipidaemia in Adult Growth Hormone (GH) Deficiency and the Effect of GH Replacement Therapy: A Review

Adult growth hormone (GH) deficiency is associated with a lipid profile known to be related to atherosclerosis. GH replacement therapy improves the lipid profile with the exception of lipoprotein (a) concentrations, which tend to increase after GH therapy. Plasma lipid concentrations depend on its plasma carriers, the lipoproteins. Possible mechanisms involved in the dyslipidaemia of GH-deficient patients and the effects of GH replacement therapy are discussed with a special focus on hepatic lipoprotein metabolism.

Recombinant human growth hormone: old and novel uses

Recent studies of the growth hormone insulinlike growth factor I (IGFI) axis suggest that these hormones are involved in several physiologic processes, in addition to growth. Thus, several lines of evidence indicate an increasingly important role for recombinant human growth hormone as a part of the modern therapeutic armamentarium. In addition to the treatment of children with growth hormone deficiency, administration of growth hormone appears to be of considerable benefit to girls with Turner syndrome, children with chronic renal failure, and adults with growth hormone deficiency or human immunodeficiency virus (HIV) wasting syndrome. Moreover, its therapeutic use is being investigated in other conditions, such as children with idiopathic short stature, the healthy elderly, and the critically ill. However, long-term surveillance among growth hormone recipients is needed to fully evaluate its risk-benefit profile.

Effects of four years' treatment with biosynthetic human growth hormone (GH) on glucose homeostasis, insulin secretion and lipid metabolism in GH-deficient adults

OBJECTIVE

To study the effects of long-term growth hormone (GH) treatment on lipid metabolism and carbohydrate tolerance in GH-deficient adults.

DESIGN

Open trial of GH treatment for 4 years. GH dose was (median, range) 0.025 (0.010-0.050) IU/kg daily.

PATIENTS

Thirteen GH-deficient hypopituitary adults (seven men, six women), aged (median, range) 47 (24-65) years were followed for 4 years.

MEASUREMENTS

Fasting lipids, lipoproteins, apolipoproteins, glucose and insulin concentrations were measured at yearly intervals during GH therapy. A 75-g oral glucose tolerance test (OGTT) was also performed yearly, during which circulating glucose and insulin were measured at 30-minute intervals for 3 h.

RESULTS

Fasting total and low density lipoprotein (LDL) cholesterol concentrations decreased on GH therapy, but no change was observed in fasting triglyceride or high density lipoprotein (HDL) concentrations. Compared to pretreatment values, total and LDL cholesterol levels were significantly lower at 1 year (mean +/- SEM) (6.39 +/- 0.46 vs. 5.71 +/- 0.38 mmol/l, P < 0.05; 4.46 +/- 0.36 vs. 3.24 +/- 0.20 mmol/l, P < 0.01, respectively) and the reductions were maintained for the 4 years. Apolipoproteins A-1 and B did not differ significantly from the pretreatment levels. Fasting plasma glucose increased significantly at the first year (4.9 +/- 0.1 vs. 5.3 +/- 0.1 mmol/l, P < 0.05) but it returned to the pretreatment value in the following years. Fasting plasma insulin increased significantly at 1 year (4.3 (1.0-13.6) vs. 11.9 (1.2-26.9) mU/l, P < 0.05) and showed a progressive downward trend but remained significantly raised throughout the subsequent years. The 3-h area under the glucose curve (AUC) during the OGTT tended to be increased at the first year (P = 0.07) and it returned to the pretreatment level in the following years. The AUC of plasma insulin was significantly raised at 1 year (P = 0.024) and it returned to the pretreatment level in the following years.

CONCLUSIONS

Four years of GH therapy in GH-deficient adults resulted in a sustained improvement in total and LDL cholesterol concentrations. Mild fasting hyperinsulinaemia persisted, although an initial deterioration in glucose tolerance, associated with post-glucose hyperinsulinaemia, was not sustained.

Effect of growth hormone treatment in patients with chronic fatigue syndrome: a preliminary study

The efficacy of growth hormone (GH) therapy was evaluated in patients with chronic fatigue syndrome (CFS) who had peak serum GH levels below 10 microg/l during stage-controlled sleep. Twenty patients (7 men, 13 women; age range, 30-60 years) with CFS were randomized to receive placebo or GH therapy, 6.7 microg/kg/day (0.02 IU/kg/day), for 12 weeks. Following this double-blind treatment period, the 17 patients remaining in the study were given GH therapy at the above dose for an open period of 9 months. Mean (+/- SD) serum levels of insulin-like growth factor I (IGF-I) increased during GH treatment, from 173 +/- 46 microg/I to 296 +/- 89 microg/l (P < 0.001); IGF-I SDS values increased from -0.45 +/- 1.14 to +1.43 +/- 1.09 (P < 0.001). Fat-free mass and total body water were significantly increased after 12 months of treatment. Although quality of life, as assessed using two different questionnaires, did not improve significantly during GH treatment, four patients were able to resume work after a long period of sick leave.

Basal growth hormone levels in women are positively correlated with high-density lipoprotein cholesterol and apolipoprotein A-I independently of insulin-like growth factor 1 or insulin

Previous studies in growth hormone (GH)-deficient or acromegalic patients yielded contradictory results on the effect of GH on lipoprotein metabolism. In a cross-sectional study, we analyzed the relationships between unstimulated GH, insulin-like growth factor 1 (IGF1), insulin, and lipoprotein metabolism in 44 non-obese young women. On univariate analysis, basal serum levels of GH correlated positively with triglycerides, high-density lipoprotein (HDL) cholesterol, apolipoprotein A-I (apoA-I) and apoA-II and negatively with lipoprotein lipase (LPL) activity. These associations remained significant on multivariate analyses that, in addition to GH, took into account the effects of insulin or C-peptide, as well as the effects of total, protein-bound, or free IGF1. In most cases, the relationships of these lipid parameters with insulin/C-peptide and IGF1 and its free or protein-bound subfractions were opposite of those with GH and not significant. Thus, GH appears to regulate the metabolism of HDL and triglycerides independently of IGF1 and insulin.

The insulin-like growth factor axis and plasma lipid levels in the elderly

The activity of the hypothalamic-GH-insulin-like growth factor (IGF) network declines with age. It has recently been shown that increased cardiovascular mortality occurs in adults with GH deficiency. As hypercholesterolemia is common in GH-deficient adults, and because there is experimental evidence that GH may play a role in regulating plasma cholesterol, we decided to investigate the activity of the GH-IGF axis in an elderly population by measuring serum IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) levels and to study their relationship with blood lipid levels. One hundred and thirty-two elderly subjects, 52 men and 80 women, were studied (age range, 60-91 yr). Men had significantly lower levels of IGFBP-3, high density lipoprotein cholesterol (HDL-C) and apoprotein A1 (ApoA1) compared to the women, whereas IGF-I and IGF-II were only slightly lower. Using linear regression analysis, we observed an inverse relationship of age with IGF-I (r = -0.35; P < 0.001), IGF-II (r = 0.40; P < 0.001), IGFBP-3 (r = 0.52; P < 0.001), body mass index, and lipid levels. Univariate regression analysis showed a strong and positive correlation of both IGF-I and IGFBP-3 with HDL-C and ApoA1. Partial correlation analysis, after adjustment for age and body mass index, showed that IGFBP-3 and IGF-II were still significantly and positively related to HDL-C and ApoA1. Furthermore, a strong association was documented among IGF-I, IGF-II, and IGFBP-3. These data demonstrate that even in an elderly population, further aging is accompanied by a progressive decline in circulating IGF-I, IGF-II, and IGFBP-3, suggesting a continuing diminution of the GH-IGF axis throughout aging. Moreover, the strong correlation between HDL-C and an index of GH secretion, such as IGFBP-3, suggests that GH might play an important role in lipid metabolism in healthy elderly subjects.

Effects of nandrolone decanoate (Decadurabolin) on serum Lp(a), lipids and lipoproteins in women with postmenopausal osteoporosis

Although lipoprotein(a) (Lp(a)) concentrations are mainly regulated genetically, it has been reported that variations in sex hormone concentrations may have effects on serum Lp(a). We evaluated the effect of nandrolone decanoate, a testosterone-derived synthetic anabolic steroid, on serum Lp(a), lipids and lipoproteins in 19 postmenopausal women who were given parenteral nandrolone decanoate (Decadurabolin) once a week for 3 weeks. At the 4th week, a significant decrease was observed for total cholesterol (p = 0.003), Lp(a) (p = 0.0003), apolipoprotein A-I (apo A-I) (p < 0.0001), and high density lipoprotein-cholesterol (HDL-C) (p < 0.0001). Moreover, a significant decrease in serum albumin concentration (p = 0.002) was concomitantly observed. We conclude that the administration of nandrolone decanoate significantly affects the lipid profile of postmenopausal women, showing controversial effects in terms of cardiovascular risk.

Serum lipids, lipoprotein lp(a), and plasminogen activator inhibitor-1 in patients with Turner's syndrome before and during growth hormone and estrogen therapy

OBJECTIVE

To evaluate whether girls with Turner's syndrome have an increased risk for cardiovascular disease due to alterations in their lipoprotein metabolism.

DESIGN

Controlled clinical study.

SETTING

Private academic hospital.

PATIENT(S)

Fifteen untreated girls with Turner's syndrome were studied initially; 11 of these patients were evaluated further while on therapy.

INTERVENTION(S)

Serum lipids, lipoprotein lp(a), and plasminogen activator (PA) inhibitor-1 were measured before and during 6 months of either GH or estrogen (E) treatment.

MAIN OUTCOME MEASURE(S)

Serum lipids, lipoprotein lp(a), and PA inhibitor-1 (PAI-1).

RESULT(S)

Total and low-density lipoprotein (LDL) cholesterol, triglycerides, lipoprotein lp(a), and PA inhibitor-1 levels were normal in Turner's syndrome patients compared with age-matched controls; HDL cholesterol was increased. During GH treatment, a significant decrease in total and LDL cholesterol was noted, whereas lipids, lipoprotein(a), and PA inhibitor-1 levels did not change with E therapy.

CONCLUSION(S)

The normal lipoproteins of untreated adolescents with Turner's syndrome, as well as the further decrease of total and LDL cholesterol during GH treatment, would seem to indicate that lipoproteins do not increase the cardiovascular risk of these girls.

Basal growth hormone levels are positively correlated with high-density lipoprotein cholesterol levels in women

Previous studies in patients with either a deficiency or an excess of growth hormone (GH) yielded contradictory results on the regulation of lipoprotein metabolism by GH. In a cross-sectional study of 563 male and 126 female participants of the Prospective Cardiovascular Münster (PROCAM) Study, we determined biometric and demographic data, serum levels of total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein (apo)A-I, A-II, and B, and unstimulated GH levels. The median of basal GH levels was higher in women than in men. Moreover, 44.2% of men but only 8.7% of women had basal GH levels less than the detection limit of 0.05 microgram/L. The relationship between basal GH and lipoprotein metabolism was investigated by univariate and multivariate regression analysis of data from 315 men and 126 women with detectable basal GH levels. In men, GH correlated positively with HDL cholesterol and negatively with body mass index (BMI), age, and triglycerides. After multivariate analysis, the correlation with triglycerides remained independent of age and BMI. Among women, GH correlated positively with the use of hormonal contraception, HDL cholesterol, apoA-I, and apoA-II, and negatively with BMI, age, menopause, triglycerides, and apoB. With multivariate analysis, the positive correlations of GH with HDL cholesterol and apoA-I in women were independent of age. BMI, menopause, and oral contraception. We conclude that GH contributes to the regulation of HDL cholesterol levels. Moreover, in women the well-known effects of exogenous estrogen or estrogen loss on HDL metabolism may be partially mediated via GH.

The effect of growth hormone replacement therapy for up to 12 months on lipoprotein composition and lipoprotein(a) in growth hormone-deficient adults

The effect of growth hormone replacement therapy in near physiological doses on lipoprotein composition and serum lipoprotein(a) concentrations was investigated in growth hormone-deficient subjects. A randomised, double-blind, placebo-controlled trial of recombinant growth hormone was undertaken for 6 months followed by an open extension for a further 6 months (0.125 IU/kg per week for the first 4 weeks of each 6 month period and thereafter 0.25 IU/kg per week). A total of 18 patients with isolated growth hormone deficiency or hypopituitarism were studied. Lipid concentrations were estimated in lipoprotein fractions and protein concentrations were measured in low density lipoprotein (LDL). Glucose and glycated haemoglobin in blood and insulin, cholesterol, triglyceride, apolipoproteins A-I and B and lipoprotein(a) concentrations were measured in serum. In the placebo-controlled phase fasting blood glucose concentrations increased with growth hormone treatment from 5.0 +/- 0.2 to 5.8 +/- 0.2 mmol/l (P = 0.02) (mean +/- S.E.M.), although no significant changes were seen in lipids or lipoproteins. In the group receiving active treatment total serum cholesterol decreased from 6.0 +/- 0.4 to 5.2 +/- 0.3 mmol/l (P = 0.002) after 6 months, due to reduced LDL cholesterol concentrations. Low density lipoprotein protein concentrations fell (0.8 +/- 0.1 versus 0.7 +/- 0.1 g/l) (P = 0.005), and LDL phospholipid levels decreased from 0.9 +/- 0.1 to 0.7 +/- 0.1 mmol/l (P = 0.007). Serum cholesterol and LDL composition reverted to pre-treatment values by 12 months. Fasting blood glucose remained above pre-treatment values (P = 0.036) and fasting insulin was significantly increased (P = 0.044). There was no effect of growth hormone therapy on serum triglyceride, apolipoprotein or lipoprotein(a) concentrations. In conclusion, growth hormone therapy with near physiological doses has no long term effects on serum lipoprotein(a) concentrations or lipoprotein composition.

The Apo(a) gene is the major determinant of variation in plasma Lp(a) levels in African Americans

The distributions of plasma lipoprotein(a), or Lp(a), levels differ significantly among ethnic groups. Individuals of African descent have a two- to threefold higher mean plasma level of Lp(a) than either Caucasians or Orientals. In Caucasians, variation in the plasma Lp(a) levels has been shown to be largely determined by sequence differences at the apo(a) locus, but little is known about either the genetic architecture of plasma Lp(a) levels in Africans or why they have higher levels of plasma Lp(a). In this paper we analyze the plasma Lp(a) levels of 257 sibling pairs from 49 independent African American families. The plasma Lp(a) levels were much more similar in the sibling pairs who inherited both apo(a) alleles identical by descent (IBD) (r = .85) than in those that shared one (r = .48) or no (r = .22) parental apo(a) alleles in common. On the basis of these findings, it was estimated that 78% of the variation in plasma Lp(a) levels in African Americans is attributable to polymorphism at either the apo(a) locus or sequences closely linked to it. Thus, the apo(a) locus is the major determinant of variation in plasma Lp(a) levels in African Americans, as well as in Caucasians. No molecular evidence was found for a common "high-expressing" apo(a) allele in the African Americans. We propose that the higher plasma levels of Lp(a) in Africans are likely due to a yet-to-be-identified trans-acting factor(s) that causes an increase in the rate of secretion of apo(a) or a decrease in its catabolism.

Growth hormone therapy transiently increases apolipoprotein(a) in short beta-thalassaemia major children with normal growth hormone reserve

Recombinant human growth hormone (rhGH) is now available for treatment of short stature due to growth hormone (GH) deficiency. It's potential use in other causes of short stature raises concerns about adverse effects of long term treatment on carbohydrate and lipoprotein metabolism. We describe the serial changes in lipids, lipoproteins and apolipoproteins, including apo(a) in 12 children with beta-thalassaemia major undergoing rhGH treatment for 24-36 months. All showed satisfactory increases in height and weight. A significantly higher mean plasma apo(a) was observed at 3 months (102.6 U/l) versus baseline (71.4 U/l, P < 0.01, geometric means). Subsequently apo(a) levels gradually decreased returning to pretreatment levels after 36 months of rhGH treatment. There were parallel rises and falls in the apo(a) isoforms of different sizes during treatment. There were only minimal changes in the other lipid related parameters. All children had markedly reduced cholesterol levels (3.0 +/- 0.49 mmol/l, mean +/- S.D.) characteristic of their underlying disease. In conclusion the elevation of apo(a) by GH is only transient, there is no differential effect of rhGH on the large and small isoforms of apo(a) and there are no clinically significant adverse effects of rhGH treatment on lipoprotein metabolism.

Nitric oxide may mediate the hemodynamic effects of recombinant growth hormone in patients with acquired growth hormone deficiency. A double-blind, placebo-controlled study

We studied the effects of recombinant growth hormone on systemic nitric oxide (NO) formation and hemodynamics in a double-blind, placebo-controlled trial in adult patients with acquired growth hormone deficiency. 30 patients were randomly allocated to either recombinant human growth hormone (r-hGH; 2.0 IU/d) or placebo for 12 mo. In the subsequent 12 mo, the study was continued with both groups of patients receiving r-hGH. In months 1, 3, 6, 9, and 12 of each year, urine and plasma samples were collected for the determination of urinary nitrate and cyclic GMP as indices of systemic NO production, and of plasma IGF-1 levels. Cardiac output was measured in months 1, 12, and 24 by echocardiography. r-hGH induced a fourfold increase in plasma IGF-1 concentrations within the first month of treatment. Urinary nitrate and cyclic GMP excretion rates were low at baseline in growth hormone-deficient patients (nitrate, 96.8+/-7.4 micromol/mmol creatinine; cyclic GMP, 63.6+/-7.1 nmol/mmol creatinine) as compared with healthy controls (nitrate, 167.3+/-7.5 micromol/mmol creatinine; cyclic GMP, 155.2+/-6.9 nmol/mmol creatinine). These indices of NO production were significantly increased by r-hGH, within the first 12 mo in the GH group, and within the second 12 mo in the placebo group. While systolic and diastolic blood pressure were not significantly altered by r-hGH, cardiac output significantly increased by 30-40%, and total peripheral resistance decreased by approximately 30% in both groups when they were assigned to r-hGH treatment. In the second study year, when both groups were given r-hGH, there were no significant differences in plasma IGF-1, urinary nitrate, or cyclic GMP excretion, or hemodynamic parameters between both groups. In conclusion, systemic NO formation is decreased in untreated growth hormone-deficient patients. Treatment with recombinant human growth hormone normalizes urinary nitrate and cyclic GMP excretion, possibly via IGF-1 stimulation of endothelial NO formation, and concomitantly decreases peripheral arterial resistance. Increased NO formation may be one reason for improved cardiovascular performance of patients with acquired hypopituitarism during growth hormone therapy.

Recombinant growth hormone: a new cardiovascular drug therapy

GH has an important role in normal cardiovascular physiologic functioning, working indirectly through effects on IGF-1. An excess or deficiency of GH causes an increased rate of cardiovascular disease, including cardiomyopathy. A relative GH deficiency in older subjects may also increase cardiovascular morbidity and mortality risk. In replacement doses, GH can enhance myocardial contractility; can decrease peripheral vascular resistance; and can reduce total cholesterol and LDL-cholesterol values and fibrinogen and PAI levels. These effects of GH, coupled with the ability to improve skeletal muscle function and reduce adiposity, make it an attractive treatment for patients with CHF and a potential maintenance drug for elderly people. Clinical trials, including studies with GHRH that may reduce the adverse effects of GH therapy, such as hyperglycemia and hypertension, are now in progress.

The effect of growth hormone on low-density lipoprotein cholesterol and lipoprotein (a) levels in familial hypercholesterolemia

Severe elevations of low-density lipoprotein (LDL) cholesterol are not always normalized with conventional drugs. Growth hormone decreases LDL cholesterol levels, in part by augmenting liver LDL receptor activity. This increase may be on the order of magnitude of the increase induced by statins. We investigated the effect of growth hormone in familial hypercholesterolemia (FH) in a randomized, double-blind, placebo-controlled study. Thirty-one men with FH aged 20 to 48 years, of whom 81% had a known LDL receptor gene mutation, discontinued all lipid-lowering drugs 6 weeks before the study. Dietary stabilization continued for 5 more weeks, followed by single-blind placebo injections for 1 week. Thereafter, 16 subjects were allocated to recombinant growth hormone 0.05 IU/kg/d and 15 to placebo injected subcutaneously for 12 weeks. Baseline lipid levels were similar in both groups. One subject in the growth hormone group withdrew after 8 weeks due to shoulder pain. Mean compliance among the rest of the subjects was 98%. The mean change in LDL cholesterol was -0.46 mmol/L (95% confidence interval [CI], -1.00 to 0.09 mmol/L) in the growth hormone group versus 0.08 mmol/L (95% CI, -0.55 to 0.71 mmol/L) in the placebo group (difference not significant). No changes occurred in the levels of other lipids, lipoprotein particles, or apolipoproteins, with the exception of lipoprotein(a) [Lp(a)]. The median changes in Lp(a) were 33% (interquartile range, 2% to 53%) and -15% (interquartile range, -22% to 18%) in the growth hormone and placebo groups, respectively (P = .02). We conclude that the effect of growth hormone on LDL cholesterol levels in FH is less than expected, based on its LDL-catabolic effects, and is counteracted by profound increases in Lp(a) levels, resulting in unchanged levels of apolipoprotein B. Thus, growth hormone is probably not useful as adjunctive therapy in FH.

Growth Hormone therapy for adult Growth Hormone deficiency

GH deficiency in adult life is associated with a number of adverse biological changes including osteopenia, reduced exercise capacity, altered body composition, deleterious alterations in the lipid profile and insulin status, and reduced quality of life. Potentially, most of these changes can be reversed by GH replacement therapy. In an era of health rationing, however, GH replacement is unlikely to be offered to every GH-deficient adult. Therefore, we have proposed a strategy aimed at delineating which adults with GH deficiency might benefit most from GH therapy.