Serum lipoproteins in acromegaly before and 6-15 months after transsphenoidal adenomectomy

Effects of endocrine disorders on lipids and lipoproteins

Endocrine diseases may be associated with dyslipidaemia and may increase atherosclerotic cardiovascular disease (ASCVD) risk. This chapter describes changes in lipids and lipoproteins in diseases of the pituitary, thyroid, adrenal glands, ovaries, and testes, the mechanisms for these changes, ASCVD risk in these endocrine disorders, and whether treatment of the endocrine disorder improves the lipid profile and reduces ASCVD risk. Acromegaly, GH deficiency, Cushing syndrome, chronic glucocorticoid replacement, hypothyroidism, PCOS and male hypogonadism can increase LDL-C and/or TG. Marked reductions in LDL-C are associated with hyperthyroidism, and extremely low HDL-C levels with testosterone and/or other anabolic steroid abuse. Acromegaly, GH deficiency, Cushing syndrome, and chronic glucocorticoid replacement are associated with increased ASCVD risk. Treatment of acromegaly, GH deficiency, hypothyroidism, Cushing syndrome, and testosterone deficiency reduce LDL-C, although statin therapy may still be needed. Effects on ASCVD are not known.

Lipid Management in Patients with Endocrine Disorders: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

This guideline will provide the practicing endocrinologist with an approach to the assessment and treatment of dyslipidemia in patients with endocrine diseases, with the objective of preventing cardiovascular (CV) events and triglyceride-induced pancreatitis. The guideline reviews data on dyslipidemia and atherosclerotic cardiovascular disease (ASCVD) risk in patients with endocrine disorders and discusses the evidence for the correction of dyslipidemia by treatment of the endocrine disease. The guideline also addresses whether treatment of the endocrine disease reduces ASCVD risk.

CONCLUSION

This guideline focuses on lipid and lipoprotein abnormalities associated with endocrine diseases, including diabetes mellitus, and whether treatment of the endocrine disorder improves not only the lipid abnormalities, but also CV outcomes. Based on the available evidence, recommendations are made for the assessment and management of dyslipidemia in patients with endocrine diseases.

Changes in metabolic parameters and cardiovascular risk factors after therapeutic control of acromegaly vary with the treatment modality. Data from the Bicêtre cohort, and review of the literature

CONTEXT

Untreated acromegaly is associated with increased morbidity and mortality due to malignant, cardiovascular, and cerebrovascular disorders. Effective treatment of acromegaly reduces excess mortality, but its impact on cardiovascular risk factors and metabolic parameters are poorly documented.

AIM

We analyzed changes in cardiovascular risk factors and metabolic parameters in patients receiving various treatment modalities.

PATIENTS AND METHODS

We retrospectively studied 96 patients with acromegaly, both at diagnosis and after IGF-I normalization following surgery alone (n = 51) or medical therapy with first generation somatostatin analogues (SSA, n = 23), or pegvisomant (n = 22). Duration of follow-up was 77 (42-161) months, 75 (42-112) months, and 62 (31-93) months, in patients treated with surgery alone, SSA, and pegvisomant, respectively. In all the cases except four, patients treated medically had underwent previous unsuccessful surgery.

RESULTS

IGF-I normalization was associated with increased body weight, decreased systolic blood pressure (SBP) in hypertensive patients, decreased fasting plasma glucose (FPG) and HOMA-IR and HOMA-B levels, increased HDL cholesterol (HDLc); whereas, LDL cholesterol (LDLc) was not significantly different. Plasma PCSK9 levels were unchanged in patients with available values. Cardiovascular and metabolic changes varied with the treatment modality: surgery, but not pegvisomant, had a beneficial effect on SBP; FPG decreased after surgery but increased after SSA; the decline in HOMA-IR was only significant after surgery; pegvisomant significantly increased LDLc and total cholesterol; whereas SA increased HDLc and had no effect on LDLc levels.

CONCLUSION

Treatments used to normalize IGF-I levels in patients with acromegaly could have differential effects on cardiovascular risk factors and metabolic parameters.

Challenges in the diagnosis and management of acromegaly: a focus on comorbidities

INTRODUCTION

Acromegaly is a rare, insidious disease resulting from the overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), and is associated with a range of comorbidities. The extent of associated complications and mortality risk is related to length of exposure to the excess GH and IGF-1, thus early diagnosis and treatment is imperative. Unfortunately, acromegaly is often diagnosed late, when patients already have a wide range of comorbidities. The presence of comorbid conditions contributes significantly to patient morbidity/mortality and impaired quality of life.

METHODS

We conducted a retrospective literature review for information relating to the diagnosis of acromegaly, and its associated comorbidities using PubMed. The main aim of this review is to highlight the issues of comorbidities in acromegaly, and to reinforce the importance of early diagnosis and treatment.

FINDINGS AND CONCLUSIONS

Successful management of acromegaly goes beyond treating the disease itself, since many patients are diagnosed late in disease evolution, they present with a range of comorbid conditions, such as cardiovascular disease, diabetes, hypertension, and sleep apnea. It is important that patients are screened carefully at diagnosis (and thereafter), for common associated complications, and that biochemical control does not become the only treatment goal. Mortality and morbidities in acromegaly can be reduced successfully if patients are treated using a multimodal approach with comprehensive comorbidity management.

Outcome of complications in acromegaly patients after long-term disease remission

Acromegaly patients suffer from pathologically high growth hormone (GH) and IGF-1 levels that in 99% of cases is due to a GH-producing pituitary adenoma. During active disease, GH excess is associated with a number of pathological conditions, such as hypertension, hypertrophic cardiomyopathy, sleep apnea, arthropathy, vertebral fractures and insulin resistance. After adequate treatment in the form of transsphenoidal surgery, radiotherapy, medical treatment or by a combination of these treatment modalities, several comorbid conditions improve considerably. However, despite long-term biochemical disease control, the prevalence of late manifestations of GH excess is high and significantly impair quality of life. In addition, there is evidence that adequate treatment is not able to normalize mortality risk in these patients. In this review, we critically evaluate the long-term consequences of acromegaly after treatment, focusing on comorbid conditions, quality of life and mortality. We also discuss ongoing challenges in the management of acromegaly patients.

Prospective study of surgical treatment of acromegaly: effects on ghrelin, weight, adiposity, and markers of CV risk

CONTEXT

Although epidemiological studies have found that GH and IGF-1 normalization reduce the excess mortality of active acromegaly to expected rates, cross-sectional data report some cardiovascular (CV) risk markers to be less favorable in remission than active acromegaly.

OBJECTIVE

The objective of the study was to test the hypothesis that remission of acromegaly after surgical therapy increases weight and adiposity and some CV risk markers and these changes are paralleled by a rise in ghrelin.

DESIGN

Forty-two adults with untreated, active acromegaly were studied prospectively. Changes in outcome measures from before to after surgery were assessed in 26 subjects achieving remission (normal IGF-1) and 16 with persistent active acromegaly (elevated IGF-1) after surgery.

SETTING

The study was conducted at tertiary referral centers for pituitary tumors.

MAIN OUTCOME MEASURES

Endocrine, metabolic, and CV risk parameters, anthropometrics, and body composition by dual-energy X-ray absorptiometry were measured.

RESULTS

Remission increased total ghrelin, body weight, waist circumference, C-reactive protein, homocysteine, high-density lipoprotein, and leptin and reduced systolic blood pressure, homeostasis model assessment score, triglycerides, and lipoprotein (a) by 6 months and for 32 ± 4 months after surgery. The ghrelin rise correlated with the fall in the levels of GH, IGF-1, and insulin and insulin resistance. Weight, waist circumference, and ghrelin did not increase significantly in the persistent active acromegaly group. Total body fat, trunk fat, and perentage total body fat increased by 1 year after surgery in 15 remission subjects: the increase in body fat correlated with the rise in total ghrelin.

CONCLUSIONS

Although most markers of CV risk improve with acromegaly remission after surgery, some markers and adiposity increase and are paralleled by a rise in total ghrelin, suggesting that these changes may be related. Understanding the mechanisms and long-term implications of the changes that accompany treatment of acromegaly is important to optimizing management because some aspects of the postoperative profile associate with the increased metabolic and CV risk in other populations.

Effects of growth hormone deficiency on body composition and biomarkers of cardiovascular risk after definitive therapy for acromegaly

BACKGROUND

Both growth hormone (GH) excess and GH deficiency are associated with abnormalities in body composition and biomarkers of cardiovascular risk in patients with pituitary disorders. However, the effects of developing GH deficiency after definitive treatment of acromegaly are largely unknown.

OBJECTIVE

To determine whether development of GH deficiency after definitive therapy for acromegaly is associated with increased visceral adiposity and biomarkers of cardiovascular risk compared with GH sufficiency after definitive therapy for acromegaly.

DESIGN

Cross-sectional.

PATIENTS

We studied three groups of subjects, all with a history of acromegaly (n = 76): subjects with subsequent GH deficiency (GHD; n = 31), subjects with subsequent GH sufficiency (GHS; n = 25) and subjects with active acromegaly (AA; n = 20). No study subjects were receiving somatostatin analogues, dopamine agonists or hGH.

MEASUREMENTS

Body composition (by DXA), abdominal adipose tissue depots (by cross-sectional CT), total body water (by bioimpedance analysis) and carotid intima-media thickness (IMT) were measured. Fasting morning serum was collected for high-sensitivity C-reactive protein (hsCRP), lipids and lipoprotein levels. An oral glucose tolerance test was performed, and homoeostasis model of assessment-insulin resistance (HOMA-IR) was calculated.

RESULTS

Abdominal visceral adipose tissue, total adipose tissue and total body fat were higher in subjects with GHD than GHS or AA (P < 0·05). Subcutaneous abdominal fat was higher, and fibrinogen and IMT were lower in GHD (but not GHS) than AA (P < 0·05). Patients with GHD had the highest hsCRP, followed by GHS, and hsCRP was lowest in AA (P < 0·05). Fasting glucose, 120-min glucose, fasting insulin, HOMA-IR and per cent total body water were lower in GHD and GHS than AA (P < 0·05). Triglycerides were higher in GHS than AA (P < 0·05). Lean body mass, mean arterial pressure, total cholesterol, HDL and LDL were comparable among groups.

CONCLUSIONS

Development of GHD after definitive treatment of acromegaly may adversely affect body composition and inflammatory biomarkers of cardiovascular risk but does not appear to adversely affect glucose homoeostasis, lipids and lipoproteins, or other cardiovascular risk markers.

Serum proteome changes in acromegalic patients following transsphenoidal surgery: novel biomarkers of disease activity

CONTEXT

Transsphenoidal adenomectomy is the primary treatment for acromegaly. However, assessment of the therapeutical outcome remains problematic since the existing biomarkers of disease activity frequently show discordant results.

OBJECTIVE

To discover novel serum biomarkers of disease activity in acromegalic patients before and after surgery.

DESIGN

Serum samples of eight newly diagnosed acromegaly patients before and after transsphenoidal surgery were analyzed for proteomic changes by two-dimensional gel electrophoresis. Protein spots displaying statistically significant changes, pre- versus post-surgery, were identified by mass spectrometry (MS), tandem MS (MS/MS), and western blot analysis.

RESULTS

Six protein spots displaying decreased intensities after surgery were identified as transthyretin (two isoforms), haptoglobin α2, β-hemoglobin, and apolipoprotein A-1 (two isoforms). One protein spot, identified as complement C4B precursor, was increased after the surgery.

CONCLUSIONS

Seven serum protein spots were differentially expressed following surgery in acromegalic patients. The identified proteins represent potential novel biomarkers to assess the effectiveness of surgical treatment in acromegalic individuals. Future studies will validate the use of the identified proteins as biomarkers of disease activity after medical treatment of acromegaly.

The treatment with growth hormone receptor antagonist in acromegaly: effect on vascular structure and function in patients resistant to somatostatin analogues

BACKGROUND

Acromegaly is known to be associated to vascular damage characterized by an increase of vascular wall thickness and an impairment of vascular function.

AIM

The aim of this study was to evaluate the effect of medical treatment with the GH receptor antagonist pegvisomant on vascular structure and function in acromegalic patients resistant to somatostatin analogues.

PATIENTS

Ten patients (4 males and 6 females, 28-58 yr) and 20 sex-, age-, and body mass index-matched healthy controls entered the study. All patients were treated for 18 months with pegvisomant at doses ranging from 10 to 40 mg/day.

OUTCOME MEASURES

Primary outcome measures were measurement of carotid arteries intima-media thickness (IMT), and brachial arteries flow mediated dilation (FMD); secondary outcome measures were blood pressure, blood glucose and lipids levels.

RESULTS

Carotid arteries maximal IMT was significantly higher in patients than in controls at baseline (1.18±0.59 vs 0.69±0.13, p=0.001) and slightly, but not significantly, decreased after treatment (0.97±0.17). Brachial arteries FMD was significantly lower in patients than controls at baseline (7.5±2.5 vs 13.1±1.4, p<0.001) and significantly increased after treatment (8.8±3.7, p=0.016). Systolic (SBP) and diastolic (DBP) blood pressure values, serum glucose and insulin levels and homeostasis model assessment (HOMA) index were higher, whereas HDL-cholesterol levels were lower in patients than controls at baseline. After treatment, SBP and DBP, as well as serum glucose and insulin levels and HOMA index significantly decreased whereas no significant change was found in serum lipid profile.

CONCLUSIONS

The results of the current study suggested that long-term treatment with pegvisomant induced a slight reduction of carotid arteries wall thickness and a significant improvement of brachial arteries vascular function in patients with acromegaly resistant to somatostatin analogues.

Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects

OBJECTIVE

To identify biomarkers of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) action in human serum.

BACKGROUND

The search for new markers of GH activity has received extensive attention given that the current biomarkers (IGF-1, IGFBP-3 and collagen peptides) show substantial variability in the population, and are not reliably predictive of either the physiologic effects of GH therapy or the detection of GH abuse by athletes. GH releasing hormone (GHRH) is a polypeptide synthesized in the hypothalamus that binds to receptors on pituitary somatotropes to promote the synthesis and release of GH. Serum GH and IGF-1 levels have been shown to increase with administration of GHRH or CJC-1295, a long-acting GHRH analog.

DESIGN

Sera from 11 healthy young adult men before and one week after CJC-1295 injection were analyzed by two-dimensional gel electrophoresis for proteomic changes. Serum proteins displaying significant changes before and after treatment were subsequently identified using mass spectrometry. In addition, correlations between these proteins and GH or IGF-1 levels were evaluated.

RESULTS

Two protein spots that displayed decreased intensities after treatment were identified as an apolipoprotein A1 isoform and a transthyretin isoform. Three protein spots upregulated by CJC-1295 treatment included beta-hemoglobin, a C-terminal fragment of albumin, and a mix of an immunoglobulin fragment and another C-terminal albumin fragment. A linear relationship was found between the spot containing immunoglobulin and albumin fragments and IGF-1 levels.

CONCLUSIONS

Although the molecular mechanisms linking the identified proteins to GH and IGF-1 biological activity remain to be clarified, the results suggest that they represent potential biomarkers of GH and/or IGF-1 action.

Amelioration of cardiovascular risk factors with partial biochemical control of acromegaly

OBJECTIVE

Complete remission of acromegaly is associated with favourable changes in cardiovascular risk parameters. We evaluated the effects of suboptimal therapy on haemodynamic, metabolic, inflammatory and coagulation cardiovascular risk indices.

DESIGN AND METHODS

Eighteen acromegalic patients on somatostatin analogues, with incomplete biochemical control, were evaluated at diagnosis and 6 months after treatment and compared to 15 healthy age- and body mass index (BMI)-matched controls. Measurements of blood pressure, GH, IGF-I, glucose, insulin, glycated haemoglobin (HbA1c), lipids, apolipoprotein A1 (apoA1), apoB, high-sensitivity C-reactive protein (hs-CRP), fibrinogen, plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (tPA) and circulating thrombomodulin were performed in all study participants, followed by an oral glucose tolerance test (OGTT). Insulin sensitivity (IS) was expressed by the Matsuda index (OGTT(ISI)).

RESULTS

Partial control of acromegaly resulted in a significant reduction in systolic and diastolic blood pressure, glucose, insulin, HbA1c, total (T-C) and low density lipoprotein cholesterol (LDL-C) and triglyceride levels, and a significant increase in apoA1, high density lipoprotein cholesterol (HDL-C) and OGTT(ISI) compared to pretreatment levels. Plasma fibrinogen and PAI-1 levels fell significantly [respectively (mean +/- SEM), 11.04 +/- 0.41 vs. 10.12 +/- 0.34 micromol/l, P = 0.003 and 9.6 +/- 1.97 vs. 6.55 +/- 1.89 microg/l, P < 0.001]. However, a marked reduction in tPA [median (IQR) 5.1 (2.5-15) vs. 3.4 (2.4-8.6) microg/l, P = 0.031] and an increase in hs-CRP [median (IQR) 0.05 (0.03-0.11) vs. 0.1 (0.06-0.23) mg/l, P < 0.001] were also noted. On treatment, acromegalic patients were comparable to controls, except for OGTT(ISI), lipoprotein(a) [Lp(a)], fibrinogen and tPA and HDL-C levels. Thrombomodulin and apoB levels were not affected by treatment.

CONCLUSIONS

Partial control in disease activity following somatostatin analogues results in significant improvement in a considerable number of cardiovascular risk markers in acromegaly.

Baseline characteristics and the effects of two years of growth hormone (GH) replacement therapy in adults with GH deficiency previously treated for acromegaly

CONTEXT

The effects of GH replacement in GH-deficient (GHD) adults previously treated for acromegaly are not well known. OBJECTIVE, DESIGN, AND PATIENTS: In this single-center, open-labeled, prospective study, 10 consecutive GHD adults with cured acromegaly (A group) and 10 matched GHD adults with previous nonfunctioning hypopituitary disease (NF group) were included. Comparisons were made at baseline and in the responses in body composition, muscle strength, bone mass, and metabolic indices during 2 yr of GH replacement.

RESULTS

At baseline, upper leg local muscle endurance and serum low-density lipoprotein-cholesterol concentration were more impaired in the A group. The A group contained three patients with hypertension, one with diabetes mellitus type 2, and one with hyperlipidemia. The NF group had only one patient with hypertension. There were no significant between-group differences in the responses to the GH therapy. Body composition and serum lipid pattern improved in both groups without any deterioration of glucose homeostasis. At study end, no difference remained between the two groups in any variable. During the 2-yr treatment, one patient had a myocardial infarction and two had cerebral infarctions in the A group, whereas no vascular event occurred in the NF group.

CONCLUSIONS

GHD patients with previous acromegaly have an impaired cardiovascular risk profile and decreased local muscle endurance as compared with other GHD patients. Two-year GH replacement eliminated these differences, but vascular events occurred more frequently in the A group. Therefore, GHD patients with cured acromegaly will benefit from GH replacement, but careful monitoring of cardiovascular status is needed.

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.

Growth hormone receptor deficiency results in blunted ghrelin feeding response, obesity, and hypolipidemia in mice

We have previously shown that growth hormone (GH) overexpression in the brain increased food intake, accompanied with increased hypothalamic agouti-related protein (AgRP) expression. Ghrelin, which stimulates both appetite and GH secretion, was injected intracerebroventricularly to GHR-/- and littermate control (+/+) mice to determine whether ghrelin's acute effects on appetite are dependent on GHR signaling. GHR-/- mice were also analyzed with respect to serum levels of lipoproteins, apolipoprotein (apo)B, leptin, glucose, and insulin as well as body composition. Central injection of ghrelin into the third dorsal ventricle increased food consumption in +/+ mice, whereas no change was observed in GHR-/- mice. After ghrelin injection, AgRP mRNA expression in the hypothalamus was higher in +/+ littermates than in GHR-/- mice, indicating a possible importance of AgRP in the GHR-mediated effect of ghrelin. Compared with controls, GHR-/- mice had increased food intake, leptin levels, and total and intra-abdominal fat mass per body weight and deceased lean mass. Moreover, serum levels of triglycerides, LDL and HDL cholesterol, and apoB, as well as glucose and insulin levels were lower in the GHR-/- mice. In summary, ghrelin's acute central action to increase food intake requires functionally intact GHR signaling. Long-term GHR deficiency in mice is associated with high plasma leptin levels, obesity, and increased food intake but a marked decrease in all lipoprotein fractions.

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.

Clinical indicators of biochemical remission in acromegaly: does incomplete disease control always mean therapeutic failure?

OBJECTIVE

Correction of GH and IGF-I levels are associated with improvements in insulin secretion, cardiac performance and body composition in patients with acromegaly, but whether these parallel post-treatment levels of GH-IGF-I axis activity is undefined. We investigate whether various biochemical outcomes after transsphenoidal pituitary surgery (TSS) in these patients are associated with clinically relevant differences in cardiac performance, insulin resistance and body composition.

DESIGN

Cross-sectional study of consecutive patients with acromegaly admitted to the hospital between 2001 and 2002.

PATIENTS AND METHODS

Forty-one patients after TSS for somatotroph pituitary adenoma and 23 patients with naive acromegaly serving as positive controls were enrolled in the study. Mean daily GH levels (mGH), IGF-I, leptin and lipid levels, glucose, insulin and GH concentrations during oral glucose tolerance test (oGTT) were measured in all study participants. Insulin resistance was measured by homeostatic model index (R(HOMA)). Body composition was assessed by dual-energy X-ray absorptiometry. Left ventricular mass index (LVM(i)) and cardiac index (C(i)) were determined by echocardiography.

RESULTS

We found no difference in cardiac indices, insulin resistance, body composition and leptin levels between patients with complete biochemical remission and those with inadequately controlled disease (P > 0.05 for all) after TSS. Cured patients had lower values (mean +/- SD) of cardiac index (2.2 +/- 0.7 vs. 3.0 +/- 1.0 l/min/m(2); P = 0.04) compared with naive patients. A similar decrease in LVM(i) was observed in controlled (108.4 +/- 30.0 g/m(2); P = 0.015) and inadequately controlled disease (108.8 +/- 30.7 g/m(2); P = 0.03) in comparison with naive disease (160.3 +/- 80.6 g/m(2)). Insulin resistance and leptin changed in opposite ways. In controlled and inadequately controlled disease, R(HOMA) index was lower (2.2 +/- 1.4; P = 0.001 and 3.1 +/- 2.0; P = 0.05 vs. 5.1 +/- 3.1) while leptin concentration was higher (14.9 +/- 8.7 microg/l, P = 0.004 and 12.8 +/- 7.8 microg/l, P = 0.05 vs. 7.4 +/- 3.8 microg/l) than in naive disease. In all patients, leptin correlated negatively with cardiac index (r = -0.46; P = 0.001) and IGF-I levels (r = -0.45; P < 0.001). Independent predictors of biochemical remission, based on normal IGF-I levels only, were cardiac [P = 0.04, odds ratio (OR) 0.4; 95% confidence interval (CI) 0.2-0.9] and R(HOMA) index (P = 0.009, OR 0.6; 95% CI 0.4-0.8). Similar results were obtained if the definition of cure included both normal IGF-I levels and the ability to achieve GH nadir < 1 microg/l during oGTT. Insulin resistance (P = 0.02, OR 0.6; 95% CI 0.4-0.9) and leptin level (P = 0.002, OR 1.3; 95% CI 1.1-1.6) were independent predictors of normalized mGH values.

CONCLUSION

This study shows that cardiac indices, insulin resistance and body composition were not different between patients with complete biochemical remission and those with discordant GH and IGF-I levels. It appears that even incomplete disease control after TSS can result in improvement of these clinical markers.

Systemic complications of acromegaly: epidemiology, pathogenesis, and management

This review focuses on the systemic complications of acromegaly. Mortality in this disease is increased mostly because of cardiovascular and respiratory diseases, although currently neoplastic complications have been questioned as a relevant cause of increased risk of death. Biventricular hypertrophy, occurring independently of hypertension and metabolic complications, is the most frequent cardiac complication. Diastolic and systolic dysfunction develops along with disease duration; and other cardiac disorders, such as arrhythmias, valve disease, hypertension, atherosclerosis, and endothelial dysfunction, are also common in acromegaly. Control of acromegaly by surgery or pharmacotherapy, especially somatostatin analogs, improves cardiovascular morbidity. Respiratory disorders, sleep apnea, and ventilatory dysfunction are also important contributors in increasing mortality and are advantageously benefitted by controlling GH and IGF-I hypersecretion. An increased risk of colonic polyps, which more frequently recur in patients not controlled after treatment, has been reported by several independent investigations, although malignancies in other organs have also been described, but less convincingly than at the gastrointestinal level. Finally, the most important cause of morbidity and functional disability of the disease is arthropathy, which can be reversed at an initial stage, but not if the disease is left untreated for several years.

Diagnosis and treatment of acromegaly complications

The Pituitary Society in conjunction with the European Neuroendocrine Association held a consensus workshop to develop guidelines for diagnosis and treatment of the co-morbid complications of acromegaly. Fifty nine pituitary specialists (endocrinologists, neurosurgeons and cardiologists) assessed the current published literature on acromegaly complications in light of recent advances in maintaining tight therapeutic control of GH hypersecretion. The impact of elevated GH levels on cardiovascular disease, hypertension, diabetes, sleep apnea, colon polyps, bone disease, reproductive disorders, and neuropsychologic complications were considered. Guidelines are proposed for effective management of these complications in the context of overall acromegaly control. When appropriate, requirements for prospective evidence-based studies and surveillance database development are enunciated. Effective management of co-morbid acromegaly complications will lead to improved morbidity and mortality in acromegaly.

Effects of treatment with Sandostatin LAR on small dense LDL and remnant-like lipoproteins in patients with acromegaly

OBJECTIVE

Acromegalic patients have been shown to have an increase in the concentrations of small dense low-density lipoprotein (LDL) and remnant-like lipoprotein particles (RLP). These lipoproteins are atherogenic and may contribute to the cardiovascular risk of these patients. The aim of this study was to determine whether treatment of acromegaly using Sandostatin LAR could lower these atherogenic lipoproteins.

METHODS

Fourteen patients with active acromegaly were recruited and Sandostatin LAR, a long-acting somatostatin analogue, was given every 4 weeks by intramuscular injection for 6 months. Fasting lipids, lipoproteins, lipolytic enzymes were determined at baseline, 12 and 24 weeks after treatment. Small dense LDL was measured using density gradient ultracentrifugation and RLP-cholesterol (RLP-C) by an immunoseparation assay.

RESULTS

There was already a marked reduction in GH and IGF-1 by week 8 and, in all subjects, IGF-1 levels within their respective age-specific normal range were achieved. At week 12, plasma triglyceride significantly decreased (P < 0.01) and both HDL2 (P < 0.01) and HDL3 (P < 0.01) subfractions increased. A reduction was seen in small dense LDL concentration (P < 0.05) and RLP-C (P < 0.05). Lipoprotein lipase (LPL) activity increased (P < 0.01) and the magnitude of the increase in LPL activity correlated with the increase in HDL at 3 months (r = 0.55, P < 0.05) but not with the changes in plasma triglyceride, small dense LDL or RLP-C. The improvement in plasma lipids and lipoproteins persisted until the end of the study.

CONCLUSION

Sandostatin LAR is effective in the treatment of acromegaly and is associated with favourable changes in plasma lipids and a reduction in small dense LDL and RLP-C.

Bovine growth hormone-transgenic mice have major alterations in hepatic expression of metabolic genes

Transgenic mice overexpressing growth hormone (GH) have been extensively used to study the chronic effects of elevated serum levels of GH. GH is known to have many acute effects in the liver, but little is known about the chronic effects of GH overexpression on hepatic gene expression. Therefore, we used DNA microarray to compare gene expression in livers from bovine GH (bGH)-transgenic mice and littermates. Hepatic expression of peroxisome proliferator-activated receptor-alpha (PPARalpha) and genes involved in fatty acid activation, peroxisomal and mitochondrial beta-oxidation, and production of ketone bodies was decreased. In line with this expression profile, bGH-transgenic mice had a reduced ability to form ketone bodies in both the fed and fasted states. Although the bGH mice were hyperinsulinemic, the expression of sterol regulatory element-binding protein (SREBP)-1 and most lipogenic enzymes regulated by SREBP-1 was reduced, indicating that these mice are different from other insulin-resistant models with respect to expression of SREBP-1 and its downstream genes. This study also provides several candidate genes for the well-known association between elevated GH levels and cardiovascular disease, e.g., decreased expression of scavenger receptor class B type I, hepatic lipase, and serum paraoxonase and increased expression of serum amyloid A-3 protein. We conclude that bGH-transgenic mice display marked changes in hepatic genes coding for metabolic enzymes and suggest that GH directly or indirectly regulates many of these hepatic genes via decreased expression of PPARalpha and SREBP-1.

Estrogen agonists/antagonists may down-regulate growth hormone signaling in hepatocytes--an explanation for their impact on IGF-I, IGFBP-1, and lipoprotein(a)

Estrogen agonists/antagonists, when administered orally, exert a range of effects on hepatic function, some of which are potentially protective. These effects include reduced synthesis of IGF-I and apolipoprotein(a), and increased synthesis of IGFBP-1--shifts which arguably could decrease risk for vascular disease and certain cancers. These effects are diametrically opposite to those of growth hormone (GH), which boosts hepatic production of IGF-I and apolipoprotein(a), while suppressing that of IGFBP-1. Thus, a parsimonious explanation of these phenomena is that oral estrogen blunts the efficiency of GH signaling in the liver. Oral androgenic progestins may have the reverse effect. It may be of particular value to determine whether certain estrogen agonists/antagonists can exert relatively 'hepatospecific' activity when administered orally--thus enabling down-regulation of systemic IGF-I activity and of lipoprotein(a), without however inducing a significant increase in systemic estrogen activity. Preliminary evidence suggests that flax lignans and perhaps other phytoestrogens may have potential in this regard.

Long-term treatment outcome in acromegaly

A number of groups have developed guidelines to indicate whether an individual with acromegaly has been cured by treatment. However, studies to date do not provide a robust definition of biochemical remission of the disorder based on correlation with long-term outcome. Available data suggest that those with a random serum growth hormone (GH) level of <2.5 microg/l, or a glucose-suppressed GH level of <1 microg/l following treatment have mortality figures indistinguishable from the general population. However, the confidence limits for these mortality estimates are quite wide. It remains possible that growth hormone levels lower than 1 microg/l for random samples, or even lower when using ultrasensitive GH assays, may indicate superior outcome, but this remains to be confirmed. There are limited data relating serum insulin-like growth factor-I (IGF-I) levels to outcome, although normalisation of serum IGF-I clearly improves outcome compared with continued elevation of measurements after treatment. Current evidence suggests that a post-treatment random serum GH <2.5 microg/l and a normal serum IGF-I value defines biochemical cure. Available data suggest that achieving similar growth hormone levels after treatment also reduces the prevalence of chronic complications of the disorder, which is subsequently reflected in improved mortality.

Acromegaly: evidence for a direct relation between disease activity and cardiac dysfunction in patients without ventricular hypertrophy

BACKGROUND AND AIMS

Cardiac abnormalities, such as cardiomegaly and congestive heart failure, occur frequently in advanced acromegaly. Abnormalities of systolic and diastolic function, mostly associated with left ventricular (LV) hypertrophy, have been reported. The impact of disease activity on LV performance in patients with normal or slightly elevated LV muscle mass has not been demonstrated.

PATIENTS AND METHODS

Conventional two-dimensional/Doppler echocardiography and tissue Doppler imaging (TDI) of the mitral annulus were performed in 13 patients with active acromegaly (AA) and normal or slightly elevated LV muscle mass (< 140 g/m2) and in 19 cured/well-controlled patients (CA). A group of 21 volunteers without symptoms or signs of cardiac disease served as controls (CON). The combined myocardial performance index (Tei-Index) was determined in all patients and controls.

RESULTS

Muscle mass index of the left ventricle, ejection fraction, fractional shorting, E/ET-ratio, systolic (ST) and late diastolic (AT) annular velocities did not differ significantly between the three groups. In the AA group, the early diastolic annular velocity ET[7.13 +/- 2.11 (AA); 9.83 +/- 3.29 (CA); 10.10 +/- 1.70 m/s (CON); P < 0.05 AA vs. CA, P < 0.005 AA vs. CON] and the ET/AT-ratio [0.71 +/- 0.26 (AA); 0.95 +/- 0.33 (CA); 1.00 +/- 0.15 m/s (CON); P < 0.05 AA vs. CA, P < 0.005 AA vs. CON] were significantly reduced. Patients with AA had a longer deceleration time [209 +/- 19 (AA); 179 +/- 22 (CA); 185 +/- 26 ms (CON); P < 0.05]. The Tei-Index was significantly higher in AA in comparison with CON [0.50 +/- 0.15 (AA); 0.48 +/- 0.12 (CA); 0.41 +/- 0.10 (CON); P < 0.05 AA vs. CON]. Subjects with CA did not differ significantly from controls with respect to 2-D/Doppler echo- and TDI-derived parameters.

CONCLUSION

The data demonstrate that diastolic dysfunction can be verified by tissue Doppler imaging in patients with active acromegaly with normal or slightly elevated muscle mass of the left ventricle and seems to be related to disease activity. The Tei-Index as a sensitive combined myocardial performance index can be used to complete the assessment of systolic and diastolic LV performance in acromegalic patients.

Cardiovascular risk factors in acromegaly before and after normalization of serum IGF-I levels with the GH antagonist pegvisomant

Acromegaly is associated with premature cardiovascular mortality. GH replacement therapy decreases inflammatory markers of cardiovascular risk, but little is known about these markers in patients with acromegaly. The GH receptor antagonist, pegvisomant, reduces IGF-I levels in 98% of patients treated. We investigated the effects of GH receptor blockade on inflammatory and other cardiovascular risk markers in active acromegaly. Forty-eight patients with acromegaly and 47 age- and body mass index-matched controls were included. The study consisted of 3 parts: a cross-sectional study, a prospective randomized 12-wk placebo-controlled study, and a longitudinal open-label study of up to 18 months of pegvisomant treatment. After baseline evaluation, patients with acromegaly were randomized to placebo (n = 14), 10 mg (n = 12), 15 mg (n = 10), or 20 mg (n = 12) daily pegvisomant for 12 wk. Subsequently, all patients received at least 10 mg pegvisomant daily for up to 18 months, with dose adjustments to achieve a normal IGF-I level. Anthropometry, GH, IGF-I, and pegvisomant levels were measured monthly. C-reactive protein (CRP), IL-6, homocysteine, lipoprotein(a), glucose, insulin, triglycerides, total cholesterol, and high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol were determined at baseline, 4 and 12 wk in the placebo-controlled study and at 3-month intervals (during which IGF-I levels were normal) in the longitudinal study. In the cross-sectional study, patients had lower CRP than did controls [median, 0.3 (range, 0.2-0.8) vs. 2.0 (0.6-3.7) mg/liter; P < 0.0001] and had higher insulin [78.6 (55.8-130.2) vs. 54.5 (36.6-77.5) pM, P = 0.0051]. IL-6, homocysteine, triglycerides, lipoprotein(a), LDL cholesterol and HDL cholesterol were not different between groups. In the placebo-controlled study, CRP increased in patients treated with 20 mg pegvisomant, compared with placebo (mean +/- SEM, 13.7 +/- 3.6 vs. 0.5 +/- 3.3 mg/liter; P = 0.010). There were no significant differences in IL-6, homocysteine, glucose, insulin, triglyceride, total cholesterol, LDL cholesterol and HDL cholesterol levels. In the longitudinal open-label study (median duration, 15.6 months), CRP increased by 2.0 +/- 0.5 mg/liter (P = 0.0002). Total cholesterol and triglycerides increased (0.22 +/- 0.11 mM, P = 0.050; and 0.25 +/- 0.09 mM, P = 0.007, respectively), whereas lipoprotein(a) decreased (-70 +/- 33 mg/liter, P = 0.039). Glucose, insulin, homocysteine, HDL cholesterol, and IL-6 did not change. We conclude that patients with active acromegaly have lower CRP and higher insulin levels than healthy controls. Administration of pegvisomant increases CRP levels. We propose that GH secretory status is an important determinant of serum CRP levels, although additional studies are needed to determine the mechanism and significance of this finding.

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.

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.

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.

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.

Discontinuation of growth hormone (GH) treatment: metabolic effects in GH-deficient and GH-sufficient adolescent patients compared with control subjects. Swedish Study Group for Growth Hormone Treatment in Children

The need for continuing GH replacement in patients with childhood-onset GH deficiency continuing into adulthood has been recognized. The metabolic consequences of discontinuing GH in adolescent patients with childhood-onset GH deficiency and short stature were examined over a period of 2 yr. Forty adolescents (aged 16-21 yr) receiving GH treatment for more than 3 yr and 16 closely matched healthy controls were studied. After a baseline visit, GH treatment was discontinued. The patients were then examined with the same protocol once a year for 2 yr. Twenty-one patients had severe GH deficiency (GHD) into adulthood, whereas 19 patients were regarded as having sufficient endogenous GH secretion (GHS). After 2 yr without GH treatment, the serum insulin-like growth factor I level was lower in GHD than in both GHS and control subjects. Both before and 2 yr after GH treatment was discontinued, serum concentrations of total cholesterol (C), low density lipoprotein C, and apolipoprotein B were higher in the GHD than in both GHS and control subjects. Serum concentrations of high density lipoprotein C decreased in the GHD group and increased in the other 2 study groups. The amount of total body and abdominal fat mass throughout the study and the increment in these masses were more marked in the GHD than in the GHS and control subjects when GH treatment was discontinued. The discontinuation of GH therapy in adolescents with severe GHD continuing into adulthood results over a period of 2 yr in the accumulation of important cardiovascular risk factors that are associated with GHD in adults.

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.

Epidemiology of acromegaly

Acromegaly is a consequence of chronic growth hormone (GH) excess, due in the majority of cases to a GH-secreting pituitary adenoma, and occurring with a population prevalence of 60 per million and an incidence of 3-4 per million per year. Males and females appear to be equally affected with an average age of presentation of 44 years. Younger patients may have more aggressive tumours and higher GH concentrations. There is co-existent hyperprolactinaemia in about one third of cases, and a variable proportion of [figure: see text] tumours appear to have activating mutations of the gsp gene or other genetic abnormalities. Acute complications such as carpal tunnel syndrome, sweating and obstructive sleep apnoea are usually readily reversible with treatment of the condition, but chronic complications such as hypertension, diabetes and heart disease are less readily corrected and post-treatment GH levels of < 2.5 ug/L (5 mU/L) are needed to achieve the prevalence found in the general community. Such 'curative' levels of GH are achieved in only about 50% of patients with current therapies, and as a result there is an ongoing excess of patients with chronic complications of acromegaly leading to increased morbidity and mortality from the disorder, with observed-to-expected mortality ratios ranging from 1.6-3.3 and only approaching unity in those with growth hormone levels < 2.5 ug/L following treatment. Prognostic factors include in some studies the presence of diabetes and [table: see text] hypertension prior to diagnosis as well as measures of exposure to excessive growth hormone derived from the product of preoperative serum GH and the time from first symptoms to treatment. Overall, however, the most important prognostic variable appears to be the serum GH concentration achieved by treatment, with an increasing consensus that this needs to be < 2.5 ug/L (5 mU/L) to achieve cure of the condition.

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.

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.

Effects of 1 year of growth hormone therapy on serum lipoprotein levels in growth hormone-deficient adults. Influence of gender and Apo(a) and ApoE phenotypes

We investigated the influence of gender and apoE and apo(a) phenotypes as well as the effect of the metabolic effects of growth hormone (GH) on the effect of GH therapy on serum lipoprotein concentrations in GH-deficient (GHD) adults. Forty-four consecutive patients, 30 men and 14 women aged 46.5 (range, 19 to 76) years with GHD due mainly to pituitary tumors, were treated with recombinant human GH for 12 months. Serum concentrations of lipoproteins, insulin, thyroxine, and insulin-like growth factor-I were determined, body composition was assessed by bioelectrical impedance, and apo(a) and apoE phenotypes were analyzed. Lipoprotein(a) [Lp(a)] concentrations in the GHD subjects were compared with a gender- and apo(a) phenotype-matched control group. After 12 months of GH treatment, the total cholesterol, LDL cholesterol, and apoB concentrations decreased, the HDL cholesterol and apoE concentrations increased, and the apoA-I and triglyceride concentrations were unchanged. Before treatment, the Lp(a) concentration was similar to that in the control group. However, after 12 months of treatment, the Lp(a) concentration had increased by 44% and 101% above baseline and the control group, respectively. Men and women responded differently to GH, with a more marked increase in Lp(a) concentration and fat-free mass and a more pronounced decrease in body-fat mass in men. Apo(a) phenotypes had no major influence on the effect of GH therapy. The only significant difference between apoE phenotypes was a higher baseline Lp(a) concentration among apoE4 heterozygotes.(ABSTRACT TRUNCATED AT 250 WORDS)