Growth hormone increases and insulin-like growth factor-I decreases circulating lipoprotein(a)

Dyslipidaemia and growth hormone deficiency - A comprehensive review

Growth hormone deficiency (GHD) is a common complication of several pituitary and hypothalamic disorders and dependent on the onset of disease. It may have severe clinical implications ranging from growth retardation in childhood-onset, to impaired lipid metabolism and increased cardiovascular risk and mortality in adults. GH effectively modulates lipid metabolism at multiple levels and GHD has been associated with an atherogenic lipid profile, that can be reversed by GH replacement therapy. Despite increasing knowledge on the effects of GH on several key enzymes regulating lipid metabolism and recent breakthroughs in the development and wider availability of recombinant GH preparations, several questions remain regarding the replacement therapy in adults with GHD. This review aims to comprehensively summarize the current knowledge on (i) lipid profile abnormalities in individuals with GHD, (ii) proposed mechanisms of action of GH on lipid and lipoprotein metabolism, and (iii) clinical implications of GH replacement therapy in individuals diagnosed with GHD.

Increase of serum lipoprotein (a), an adverse effect of growth hormone treatment

A number of reports show that high endogenous, or therapeutic administration of human growth hormone (hGH) cause an increase of serum lipoprotein a, Lp(a). Being thrombogenic Lp(a) is an independent risk factor of atherosclerotic cardiovascular disease (ASCVD). Hence, it is hypothesized that the recently reported association between childhood hGH treatment and cardiovascular morbidity is probably due to the GH effect on Lp(a) synthesis. It is therefore suggested to determine serum Lp(a) levels before and during hGH treatment in children and adults.

IGF-I deficiency, longevity and cancer protection of patients with Laron syndrome

Laron syndrome (LS) is a unique model of congenital IGF-I deficiency. It is characterized by dwarfism and obesity, and is caused by deletion or mutations of the growth hormone receptor (GH-R) gene. It is hypothesized that LS is an old disease originating in Indonesia and that the mutated gene spread to South Asia, the Middle East, the Mediterranean region and South America.

Increase of classic and nonclassic cardiovascular risk factors in patients with acromegaly

OBJECTIVE

To evaluate the prevalence of classic and nonclassic cardiovascular risk factors in patients with acromegaly.

METHODS

Sixty-two patients with acromegaly (50 with active disease and 12 with controlled acromegaly) and 36 healthy persons (the control group) underwent measurement of lipids, fasting plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR) index, Lp(a), high-sensitivity C-reactive protein (hsCRP), homocysteine, and variables primarily related to thrombogenesis (fibrinogen, antithrombin III, protein C, and protein S).

RESULTS

In comparison with control subjects, patients with active acromegaly had significantly higher mean values of fasting plasma glucose, total cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein (VLDL) cholesterol, triglycerides, Lp(a), HOMA-IR, and fibrinogen as well as lower mean levels of high-density lipoprotein cholesterol and protein S. In both groups, homocysteine, antithrombin III, protein C, and hsCRP levels were similar. Moreover, patients with active acromegaly, in comparison with those who had controlled acromegaly, presented with significantly higher values of fasting plasma glucose, HOMA-IR, triglycerides, VLDL cholesterol, Lp(a), and fibrinogen, whereas hsCRP and protein S were significantly lower. Finally, low levels of high-density lipoprotein cholesterol and protein S as well as elevated values of VLDL cholesterol, triglycerides, HOMA-IR, and fasting plasma glucose were more prevalent in patients with active acromegaly than in the other groups.

CONCLUSION

Our findings demonstrate that, in comparison with control subjects and patients with controlled acromegaly, patients with active acromegaly had a higher frequency of classic and nonclassic cardiovascular risk factors. These findings are potentially very important because acromegaly is associated with a 2- to 3-fold increase in mortality rate, predominantly related to cardiovascular disease.

Age-related changes in bile acid synthesis and hepatic nuclear receptor expression

BACKGROUND

Recent data highlighted the role of nuclear receptors in the transcriptional regulation of the limiting enzyme of bile acid synthesis, cholesterol 7alpha-hydroxylase, in cellular and animal models. This study was designed to analyze the effects of age on cholesterol 7alpha-hydroxylase and related nuclear receptor expression in human livers.

DESIGN

Surgical liver biopsies were obtained in 23 patients requiring operation on the gastrointestinal tract. mRNA levels of cholesterol 7alpha-hydroxylase and related nuclear receptors and co-activators were assayed by quantitative real-time RT-PCR. Serum levels of 7alpha-hydroxy-4-cholesten-3-one, a marker of bile acid synthesis, were assayed by gas-liquid chromatography:mass spectrometry.

RESULTS

Ageing was inversely correlated with serum 7alpha-hydroxy-4-cholesten-3-one and with cholesterol 7alpha-hydroxylase mRNA levels (r = -0.44 and r = -0.45 on a semi-log scale, respectively, P < 0.05). Among different nuclear factors, cholesterol 7alpha-hydroxylase mRNA best correlated with hepatocyte nuclear factor-4 (r = 0.55 on a log scale, P < 0.05); hepatocyte nuclear factor-4 levels were also inversely correlated with age (r = -0.64 on a semi-log scale, P < 0.05). Age was inversely correlated with serum insulin-like growth factor-I levels, which were directly correlated with hepatocyte nuclear factor-4 and cholesterol 7alpha-hydroxylase expression. No suppressive effect of short heterodimer partner expression on cholesterol 7alpha-hydroxylase was observed.

CONCLUSIONS

Ageing associates with reduced bile acid synthesis, possibly related to decreased hepatic expression of hepatocyte nuclear factor-4 and consequently of cholesterol 7alpha-hydroxylase. Age-related modifications of the growth hormone/insulin-like growth factor axis might play a role. These findings may help to elucidate the pathophysiology of age-related modifications of cholesterol metabolism.

The effect of atorvastatin on serum lipoproteins in acromegaly

OBJECTIVE

Acromegaly is associated with long-term adverse effects on cardiovascular mortality and morbidity. Reducing growth hormone secretion improves well-being and symptoms, but may not significantly improve the lipoprotein profile. An additional approach to cardiovascular risk reduction in acromegaly may therefore be to target lipoprotein metabolism directly. In this study we investigated the effect of statin treatment.

DESIGN

Double blind, placebo-controlled, crossover study of the effects on circulating lipoproteins of atorvastatin 10 mg daily vs. placebo. Each treatment was given for 3 months in random order.

SUBJECTS

Eleven patients with acromegaly.

MEASUREMENTS

Lipids, lipoproteins, apolipoproteins, enzyme activity and calculated cardiovascular risk.

RESULTS

Atorvastatin treatment compared to placebo resulted in a significant decrease in serum cholesterol (5.85 +/- 1.04 mmol/l vs. 4.22 +/- 0.69 mmol/l; mean +/- SD; P < 0.001), low-density lipoprotein (LDL) cholesterol (2.95 +/- 1.07 mmol/l vs. 1.82 +/- 0.92 mmol/l; P < 0.001), very low-density lipoprotein (VLDL) cholesterol (0.31 (0.21-0.47) mmol vs. 0.23 (0.13-0.30) mmol/l median (interquartile range); P < 0.05), apolipoprotein B (111 +/- 28 mg/dl vs. 80 +/- 18 mg/dl; P < 0.001), and calculated coronary heart disease risk (6.8 (3.3-17.9) vs. 2.8 (1.5-5.7)% over next 10 years; P < 0.01). Serum triglyceride was 1.34 (1.06-1.71) mmol/l on placebo and 1.14 (0.88-1.48) mmol/l on atorvastatin (ns). HDL cholesterol, apolipoprotein A1 and Lp(a) concentrations and cholesteryl ester transfer protein and lecithin: cholesterol acyl transferase activities were also not significantly altered.

CONCLUSION

Atorvastatin treatment was safe, well tolerated and effective in improving the atherogenic lipoprotein profile in acromegaly.

Growth Hormone Induces Low-Density Lipoprotein Clearance but not Bile Acid Synthesis in Humans

OBJECTIVE

Growth hormone (GH) induces hepatic low-density lipoprotein (LDL) receptors and lowers plasma cholesterol. We characterized the influence of GH treatment on plasma LDL clearance in normal humans and investigated the relative role of LDL receptor (LDLR) activity and stimulation of bile acid synthesis in subjects with different LDLR expression.

METHODS AND RESULTS

Plasma clearance of autologous 125I-LDL was measured before and during 3 weeks of treatment with GH (0.1 IU/kg per day) in 9 healthy young males. Plasma LDL cholesterol was reduced by 13% and the fractional catabolic rate of LDL increased by 27%. More marked changes were seen in a patient with hypopituitarism substituted with GH (0.07 IU/kg per day) for 3 months. In a second study, GH dose-dependently reduced LDL cholesterol and increased Lp(a) levels in 3 groups of males: younger and elderly healthy subjects and heterozygous familial hypercholesterolemia (FH). No effect on bile acid synthesis measured by the plasma marker 7alpha-hydroxy-4-cholesten-3-one was observed. In an LDLR-deficient FH homozygote, LDL cholesterol was not affected by GH.

CONCLUSIONS

GH treatment reduces plasma LDL cholesterol by inducing LDL clearance. In humans, LDLR expression is a prerequisite for this effect, whereas it is not related to stimulation of bile acid synthesis.

Lipoprotein (a) and lipid profile in neonates from mothers with three different types of diabetes mellitus

OBJECTIVES

The metabolic components in neonates may be affected by maternal diabetes mellitus.

DESIGN AND METHODS

To investigate the alterations in lipid metabolism and the possible atherogenic risk, the lipoprotein a (Lp a), apoproteins, lipid profile, glucose concentrations were measured (ELISA, immunodiffusion and enzymatic) in 77 cord blood samples from diabetic and healthy pregnant mothers.

RESULTS

The body weight, cord glucose and both apoproteins were increased in neonates of gestational and noninsulin dependent diabetic (GDM, NIDDM) than in neonates of nondiabetic mothers (NNDM). The Lp (a) was not correlated with the blood glucose and didn't significantly increase in the three neonates groups of diabetic mothers. The apo B/apo A1 and the LDL/HDL ratios were insignificantly increased in relation to the body weight. In neonates of diabetic mothers (NDM), only the blood glucose and Lp (a) differ between both sexes.

CONCLUSION

NDM may have disturbed lipid metabolism, which require special care to them and to their mothers during the prenatal period.

Effects of GH replacement on metabolism and physical performance in GH deficient adults

GH deficiency (GHD) in adults is associated with abnormalities in body composition, metabolic derangements, sub-optimal physical performance, high incidence of adverse cardiovascular risk factors and poor quality of life. GHD adults are insulin resistant and have reduced hepatic glycogen stores, reduced insulin stimulated glucose utilization and reduced glycogen synthesis in muscle. GH replacement results in either no change or slight reduction in insulin sensitivity. Hence, it is important to monitor for the development of glucose intolerance in patients on long-term GH replacement. GHD is associated with a lipid profile known to predispose to premature atherosclerosis and cardiovascular disease, i.e. increased total and LDL cholesterol, decreased HDL cholesterol, increased small dense LDL particles and increased triglycerides. LDL-cholesterol abnormalities appear to improve with GH replacement even if maintained within physiological dose range; the greatest improvement occurs in those subjects with higher baseline total and LDL cholesterol values and in female patients with adult onset GHD compared with male patients with childhood onset GHD. In contrast, hypertriglyceridaemia is not corrected by GH replacement. The majority of the reports suggest GH replacement increases Lipoprotein-a levels. Long-term observation will be required to determine whether GH replacement reduces cardiovascular morbidity and mortality in GHD adults. The reduced muscle mass and strength associated with GHD has been shown to improve after GH replacement. GH treatment also improves maximal and sub-maximal exercise performance in GHD adults. The effects on protein metabolism, energy expenditure and thyroid metabolism in GHD adults are also critical.

Lipoprotein(a): an emerging cardiovascular risk factor

Lipoprotein(a) is a cholesterol-enriched lipoprotein, consisting of a covalent linkage joining the unique and highly polymorphic apolipoprotein(a) to apolipoprotein B100, the main protein moiety of low-density lipoproteins. Although the concentration of lipoprotein(a) in humans is mostly genetically determined, acquired disorders might influence synthesis and catabolism of the particle. Raised concentration of lipoprotein(a) has been acknowledged as a leading inherited risk factor for both premature and advanced atherosclerosis at different vascular sites. The strong structural homologies with plasminogen and low-density lipoproteins suggest that lipoprotein(a) might represent the ideal bridge between the fields of atherosclerosis and thrombosis in the pathogenesis of vascular occlusive disorders. Unfortunately, the exact mechanisms by which lipoprotein(a) promotes, accelerates, and complicates atherosclerosis are only partially understood. In some clinical settings, such as in patients at exceptionally low risk for cardiovascular disease, the potential regenerative and antineoplastic properties of lipoprotein(a) might paradoxically counterbalance its athero-thrombogenicity, as attested by the compatibility between raised plasma lipoprotein(a) levels and longevity.

IGF-I in a normal population: relation to psychosocial factors

OBJECTIVE

IGF-I has important actions on cell division, apoptosis, differentiation and metabolism, as well as on cell proliferation in vascular smooth muscle. Deficiency of GH, an important regulator of IGF-I, is associated with reduced well-being. IGF-I levels have been related to cognitive function in older individuals. The aim of the present study was to investigate the IGF-I concentrations in a normal population of men and women aged 20-74 years and to determine the influence of a variety of behavioural and psychosocial factors as well as metabolic factors on these concentrations.

DESIGN

Cross-sectional study.

PATIENTS

The study group consisted of 408 randomly selected people who had answered a questionnaire concerning health care utilization and quality of life that was administered to a random sample of 4200 people over age 17 from the northwestern region of greater Stockholm in 1995. Thirty-four men and 34 women were randomly selected from the age group 20-24 and from each 10-year age group between the ages of 25-75 years. Seventy-one per cent of the 408 people invited to come in for an examination agreed to attend, making a total sample size of 288 people.

MEASUREMENTS

A medical examination was performed and blood drawn in the morning after subjects had been fasting overnight. Before the examination, they were asked to fill out a questionnaire concerning lifestyle and psychosocial factors.

RESULTS

The distribution of IGF-I was positively skewed, but using logarithmically transformed IGF-I, a more symmetrical distribution was obtained. A linear inverse correlation was found between logarithmically transformed IGF-I levels and age which explained more than 40% of the variation in men and women. Linear correlation analysis between IGF-I and different parameters of health and disease, lifestyle and psychosocial factors, resulted in several significant correlations most of which disappeared after controlling for age. In the younger age group (20-44) there were positive correlations between IGF-I and psychosocial factors representing quality of life and psychological well-being. In the middle age group (45-59) higher IGF-I levels were related to better physical health, higher education and higher concentrations of lipoprotein Lp(a). In the older age group (over 59 years) higher levels of low-density lipoprotein-cholesterol (LDL-C) and lower levels of SHBG were associated with higher IGF-I levels.

CONCLUSION

In a randomly selected (nondisease) population, IGF-I concentrations show a consistent decrease with age in both men and women, accompanied by different association patterns relevant to disease risk. Levels are related to psychosocial parameters in the younger age group and metabolic impairment associated with increased cardiovascular risk in the older age groups. We speculate on the relative roles of age and cohort differences in rearing conditions in determining these differences.

Serum lipoprotein changes following IGF-I normalization using a growth hormone receptor antagonist in acromegaly

OBJECTIVE

Active acromegaly is associated with altered lipid metabolism. The purpose of this study was to investigate the effect of serum IGF-I normalization on serum lipoproteins and insulin, in patients with acromegaly receiving the GH receptor antagonist pegvisomant.

PATIENTS

Twenty patients (9 male, mean age 58.7 years, range 28-79) with active acromegaly (baseline serum IGF-I > 130% the age-related upper limit of normal) received pegvisomant and achieved a normal serum IGF-I [585.2 +/- 54.3 (mean +/- SEM) to 169.2 +/- 13.9 ng/ml, P < 0.0001].

MEASUREMENTS

Total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, triglyceride (TG), apolipoprotein B (apo B), apolipoprotein A1 (apo A1), lipoprotein a [Lp(a)] and insulin were measured in a single batch analysis on samples obtained at baseline and the first occasion of serum IGF-I normalization. Low-density lipoprotein (LDL) was calculated using the Friedewald formula. Paired analysis was performed using Student's paired t-test and the Wilcoxon signed rank test.

RESULTS

Normalization of serum IGF-I resulted in an increase in TC (5.0 +/- 0.3 to 5.7 +/- 0.4 mmol/l, P = 0.0068), an increase in LDL (3.0 +/- 0.25 to 3.7 +/- 0.31 mmol/l, P = 0.0093) and an increase in apo B (110.6 +/- 7.76 to 127.1 +/- 8.86 mg/l, P = 0.014). TC and LDL increased in all but four patients. Despite a significant fall in fasting insulin levels (9.9 to 8.3 mU/l, range 8.85-19.8 to 6.33-11.6, P < 0.001) and insulin resistance (2.7 to 1.9, range 1.2-10.4 to 1-6.2, P < 0.001), mean serum TG and HDL levels were unaffected by IGF-I normalization. The protein component of HDL, apo A1, increased (153 +/- 4 to 166.4 +/- 5.43 mg/l, P = 0.026) and Lp(a) declined (median 342 to 235 mg/l, range 60-1013 to 74-671), P = 0.0035). Baseline serum TC and LDL were below the age- and sex-matched mean population value but after normalization of serum IGF-I the distribution of serum TC and LDL values was similar to that of the general population.

CONCLUSIONS

Active acromegaly is associated with lowered mean serum TC and LDL. Successful management using pegvisomant increases lowered baseline serum TC and LDL levels, restoring the distribution of values to that of the general population, and improves insulin resistance. These findings are consistent with the reported lipoprotein changes following GH administration to normal and GH-deficient individuals.

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.

Growth hormone secretagogues: recent advances and applications

The discovery of a new class of compounds that stimulate the release of growth hormone (GH) in a manner distinctly different from growth hormone-releasing hormone (GHRH) is advancing the understanding of the mechanisms that control GH secretion. These compounds, the GH secretagogues, act at both pituitary and hypothalamic levels, and might even elicit effects in the CNS and peripheral systems. A receptor with high affinity for the GH secretagogues has been identified and several observations suggest the presence of additional receptors. The existence of these specific endogenous receptors could indicate that the mechanism of GH release is not yet fully understood. Several potential indications have been explored clinically and, as some of these compounds are orally active, they could offer attractive alternatives to recombinant human growth hormone (hGH) in treating GH disorders such as growth hormone deficiency (GHD), age-related conditions, obesity and catabolic conditions.

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.

Serum insulin-like growth factor-I (IGF-I) levels during long-term IGF-I treatment of children and adults with primary GH resistance (Laron syndrome)

Serum IGF-I levels were measured in 14 patients (9 children and 5 adults) with Laron syndrome (LS) during long-term treatment by IGF-I. Recombinant IGF-I (FK-780, Fujisawa Pharmaceutical Co. Ltd., Japan) was administered once daily subcutaneously before breakfast for 3-5 years to the children and for 9 months to the adults. The initial daily dose was 150 micrograms/kg for children and 120 micrograms/kg for adults. Before initiation of treatment the mean overnight fasting levels of serum IGF-I in the children was 3.2 +/- 0.8 nmol/l (mean +/- SEM), rising to 10 +/- 1.7 nmol/l during long-term treatment even on a dose of 120 micrograms/kg/day. The serum IGF-I levels 4 hours after injection rose from 31.2 +/- 3.5 to 48 +/- 2 nmol/l. In the adult patients, the initial basal IGF-I was 4.1 +/- 0.7 nmol/l, rising to 16.1 +/- 3.84 nmol/l after 8-9 months treatment. Serum IGF-I levels at 4 hours after injection rose in the adult patients from 24.1 +/- 5.8 up to 66.8 +/- 15.4 nmol/l. A progressively increasing half-life during long term exogenous administration of IGF-I to patients with Laron syndrome was demonstrated by following serum IGF-I dynamics after injection. Based on the fact that no antibodies to IGF-I were detected and on findings in previous studies, it is speculated that the increasing serum IGF-I levels during long-term IGF-I treatment are caused by an increase in serum IGFBP-3 induced by chronic IGF-I administration. It is concluded that treatment with IGF-I necessitates regular monitoring of serum IGF-I levels; in patients in whom the age adjusted maximal levels are exceeded, a reduction of the daily IGF-I dose is indicated to avoid undesirable effects.

Serum lipoprotein (a) concentrations among Arab children: a hospital-based study in Kuwait

Elevated lipoprotein (a) [Lp(a)] is an independent risk factor for premature atherosclerosis and coronary heart disease, both of which are prevalent among Kuwaitis. Our objective was to measure serum lipids, including Lp(a), in Arab children and compare them with values reported for other ethnic groups. To that end, serum concentrations of Lp(a), total cholesterol [T-CHOL], high density lipoprotein [HDL], low density lipoprotein [LDL], and triglyceride [TG] were assessed in 103 Arab children. The mean and median Lp(a) were 140.4 mg/l and 95 mg/l, respectively. The Lp(a) frequency distribution was skewed to the right with the highest frequencies appearing at low levels. Serum Lp(a) correlated positively with T-CHOL and LDL but did not correlate with age, HDL and TG. Only nine children (8.7%) had serum Lp(a) levels associated with increased cardiovascular risk, namely > or = 300 mg/l.

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.