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

High lipoprotein(a): Actionable strategies for risk assessment and mitigation

High levels of lipoprotein(a) [Lp(a)] are causal for atherosclerotic cardiovascular disease (ASCVD). Lp(a) is the most prevalent inherited dyslipidemia and strongest genetic ASCVD risk factor. This risk persists in the presence of at target, guideline-recommended, LDL-C levels and adherence to lifestyle modifications. Epidemiological and genetic evidence supporting its causal role in ASCVD and calcific aortic stenosis continues to accumulate, although various facets regarding Lp(a) biology (genetics, pathophysiology, and expression across race/ethnic groups) are not yet fully understood. The evolving nature of clinical guidelines and consensus statements recommending universal measurements of Lp(a) and the scientific data supporting its role in multiple disease states reinforce the clinical merit to start population screening for Lp(a) now. There is a current gap in the implementation of recommendations for primary and secondary cardiovascular disease (CVD) prevention in those with high Lp(a), in part due to a lack of protocols for management strategies. Importantly, targeted apolipoprotein(a) [apo(a)]-lowering therapies that reduce Lp(a) levels in patients with high Lp(a) are in phase 3 clinical development. This review focuses on the identification and clinical management of patients with high Lp(a). Specifically, we highlight the clinical value of measuring Lp(a) and its use in determining Lp(a)-associated CVD risk by providing actionable guidance, based on scientific knowledge, that can be utilized now to mitigate risk caused by high Lp(a).

Effects of Lipid-Modifying and Other Drugs on Lipoprotein(a) Levels-Potent Clinical Implications

The past few years have shown an ongoing interest in lipoprotein(a) (Lp(a)), a lipid molecule that has been proven to have atherogenic, thrombogenic, and inflammatory properties. Several lines of evidence, indeed, have demonstrated an increased risk of cardiovascular disease as well as calcific aortic valve stenosis in patients with elevated Lp(a) levels. Statins, the mainstay of lipid-lowering therapy, slightly increase Lp(a) levels, while most other lipid-modifying agents do not significantly alter Lp(a) concentrations, except for proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors. The latter have been shown to reduce Lp(a) levels; however, the clinical significance of this effect has not been clearly elucidated. Of note, the pharmaceutical lowering of Lp(a) may be achieved with novel treatments specifically designed for this purpose (i.e., antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs)). Large clinical trials with cardiovascular outcomes with these agents are ongoing, and their results are eagerly awaited. Furthermore, several non-lipid-modifying drugs of various classes may influence Lp(a) concentrations. We have searched MEDLINE, EMBASE, and CENTRAL databases up to 28 January 2023 and summarized the effects of established and emerging lipid-modifying drugs and other medications on Lp(a) levels. We also discuss the potent clinical implications of these alterations.

Supporting evidence for lipoprotein(a) measurements in clinical practice

High levels of lipoprotein(a) [Lp(a)] are causal for development of atherosclerotic cardiovascular disease and highly regulated by genetics. Levels are higher in Blacks compared to Whites, and in women compared to men. Lp(a)'s main protein components are apolipoprotein (apo) (a) and apoB100, the latter being the main component of Low-Density Lipoprotein (LDL) particles. Studies have identified Lp(a) to be associated with inflammatory, coagulation and wound healing pathways. Lack of validated and accepted assays to measure Lp(a), risk cutoff values, guidelines for diagnosis, and targeted therapies have added challenges to the field. Scientific efforts are ongoing to address these, including studies evaluating the cardiovascular benefits of decreasing Lp(a) levels with targeted apo(a) lowering treatments. This review will provide a synopsis of evidence-based effects of high Lp(a) on disease presentation, highlight available guidelines and discuss promising therapies in development. We will conclude with current clinical information and future research needs in the field.

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.

Lipoprotein(a) in atherosclerotic cardiovascular disease and aortic stenosis: a European Atherosclerosis Society consensus statement

This 2022 European Atherosclerosis Society lipoprotein(a) [Lp(a)] consensus statement updates evidence for the role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis, provides clinical guidance for testing and treating elevated Lp(a) levels, and considers its inclusion in global risk estimation. Epidemiologic and genetic studies involving hundreds of thousands of individuals strongly support a causal and continuous association between Lp(a) concentration and cardiovascular outcomes in different ethnicities; elevated Lp(a) is a risk factor even at very low levels of low-density lipoprotein cholesterol. High Lp(a) is associated with both microcalcification and macrocalcification of the aortic valve. Current findings do not support Lp(a) as a risk factor for venous thrombotic events and impaired fibrinolysis. Very low Lp(a) levels may associate with increased risk of diabetes mellitus meriting further study. Lp(a) has pro-inflammatory and pro-atherosclerotic properties, which may partly relate to the oxidized phospholipids carried by Lp(a). This panel recommends testing Lp(a) concentration at least once in adults; cascade testing has potential value in familial hypercholesterolaemia, or with family or personal history of (very) high Lp(a) or premature ASCVD. Without specific Lp(a)-lowering therapies, early intensive risk factor management is recommended, targeted according to global cardiovascular risk and Lp(a) level. Lipoprotein apheresis is an option for very high Lp(a) with progressive cardiovascular disease despite optimal management of risk factors. In conclusion, this statement reinforces evidence for Lp(a) as a causal risk factor for cardiovascular outcomes. Trials of specific Lp(a)-lowering treatments are critical to confirm clinical benefit for cardiovascular disease and aortic valve stenosis.

Non-genetic influences on lipoprotein(a) concentrations

An elevated level of lipoprotein(a) [Lp(a)] is a genetically regulated, independent, causal risk factor for cardiovascular disease. However, the extensive variability in Lp(a) levels between individuals and population groups cannot be fully explained by genetic factors, emphasizing a potential role for non-genetic factors. In this review, we provide an overview of current evidence on non-genetic factors influencing Lp(a) levels with a particular focus on diet, physical activity, hormones and certain pathological conditions. Findings from randomized controlled clinical trials show that diets lower in saturated fats modestly influence Lp(a) levels and often in the opposing direction to LDL cholesterol. Results from studies on physical activity/exercise have been inconsistent, ranging from no to minimal or moderate change in Lp(a) levels, potentially modulated by age and the type, intensity, and duration of exercise modality. Hormone replacement therapy (HRT) in postmenopausal women lowers Lp(a) levels with oral being more effective than transdermal estradiol; the type of HRT, dose of estrogen and addition of progestogen do not modify the Lp(a)-lowering effect of HRT. Kidney diseases result in marked elevations in Lp(a) levels, albeit dependent on disease stages, dialysis modalities and apolipoprotein(a) phenotypes. In contrast, Lp(a) levels are reduced in liver diseases in parallel with the disease progression, although population studies have yielded conflicting results on the associations between Lp(a) levels and nonalcoholic fatty liver disease. Overall, current evidence supports a role for diet, hormones and related conditions, and liver and kidney diseases in modifying Lp(a) levels.

Study on the relationship between hormone and Lp(a) in Chinese overweight/obese patients

BACKGROUND

Obesity is a risk factor for metabolic diseases and often influences hormone change. Lipoprotein (a) (Lp(a)) is associated with various metabolic diseases, but there are few studies on the relationship between Lp(a) and hormones in obese patients. This study investigated the the relationship between Lp(a) and hormones in Chinese overweight/obese people.

METHODS

A total of 410 overweight/obese patients (Body mass index (BMI) ≥ 25 kg/m²) were included and underwent sociodemographic data investigations and relevant clinical examinations. Lp(a) was analyzed by colorimetric enzymatic assays and hormone was measured with chemiluminescence immunoassay method. According to Lp(a) levels, they were categorized into 3 groups: the lower Lp(a) group (Lp(a) levels < 30 mg/dl), the moderate Lp(a) group (Lp(a) levels between 30 mg/dl and 120 mg/dl) and the higher Lp(a) group (Lp(a) levels > 120 mg/dl). The differences of hormone levels among the three groups were compared and the relationship between Lp(a) and hormones was analyzed by Spearman's rank correlation.

RESULTS

The higher Lp(a) group had significantly lower testosterone (TES) levels compared with the lower and moderate Lp(a) groups in the case of gender, age and BMI matching. Lp(a) concentration was negatively correlated with TES levels in all participants and the negative association between Lp(a) and TES levels was also observed when the analysis was stratified by gender. Additionally, the TES was statistically related with Lp(a) levels in the multiple linear regression model (95% confidence interval: - 0.451 to - 0.079).

CONCLUSIONS

TES levels was negatively associated with Lp(a) levels in Chinese overweight/obese patients.

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.

Meta-analysis of metabolic changes in children with idiopathic growth hormone deficiency after recombinant human growth hormone replacement therapy

PURPOSES

We aimed to assess the effects of recombinant human growth hormone (rhGH) replacement therapy on metabolic changes by synthesizing data from clinical trials involving children with idiopathic growth hormone deficiency (IGHD).

METHODS

Two investigators independently completed literature search, quality assessment, and data extraction. Effect-size estimates are expressed as weighted mean difference (WMD) with 95% confidence interval (CI).

RESULTS

A total of 16 clinical trials involving 1319 children were eligible for analysis. Overall analyses showed that total cholesterol was significantly decreased after rhGH replacement therapy (WMD: -0.20 mmol/l; 95% CI: -0.30 to -0.10; p < 0.001), and high-density lipoprotein was significantly increased (WMD: 0.29 mmol/l; 95% CI: 0.24 to 0.33; p < 0.001). Marginal increase was noted for low-density lipoprotein (WMD: -0.22 mmol/l; 95% CI: -0.47 to 0.22; p = 0.092). Subsidiary and meta-regression analyses revealed that length of intervention and sample size were possible causes of heterogeneity. There was a low probability of publication bias.

CONCLUSIONS

Our findings indicate an obviously favorable role of rhGH replacement therapy in lipid metabolism in children with IGHD, and this role might be dependent on length of intervention.

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.

Association Between Serum Lipid Profile and Obstructive Respiratory Events During REM and Non-REM Sleep

Purpose

Obstructive sleep apnoea (OSA) represents a risk for dyslipidaemia. Obstructive respiratory events during rapid eye movement (REM) sleep are more strongly related to the development of hypertension and diabetes than in non-REM. However, the relationship between sleep phases and serum lipid profile is unclear. We aimed to analyse the relationship between obstructive respiratory events in REM and non-REM sleep as well as serum lipid profile.

Methods

Polysomnography was performed in 94 adult subjects who did not take any lipid-modifying medications. Fasting venous blood sample was taken the following morning for total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol, lipoprotein(a), apoprotein A1 (ApoA1) and for apoprotein B (ApoB) measurements. Lipid profiles were correlated with apnoea–hypopnoea index (AHI) during REM (AHI_REM) and non-REM (AHI_NREM) stages in all subjects. In addition, lipid profiles were compared between REM-dependent OSA patients (AHI_REM ≥ 5/h, but AHI_NREM < 5/h) and control subjects (both AHI_REM and AHI_NREM < 5/h).

Results

AHI_REM correlated only with triglyceride concentrations (p = 0.04, Spearman’s rho, ρ = 0.21). In contrast, there was a significant association between AHI_NREM and triglyceride (p = 0.02, ρ = 0.23), ApoB (p = 0.03, ρ = 0.21), HDL-C (p < 0.01, ρ = − 0.32) as well as ApoA1 levels (p = 0.04, ρ = − 0.21). However, these correlations were not present after adjustment for BMI (all p > 0.05). There was no difference in the lipid profile of REM-dependent OSA subjects and healthy controls (p > 0.05).

Conclusions

Altered serum lipid profile is equally associated with a disturbed REM and non-REM sleep in OSA. Obesity must be considered as a strong covariate when interpreting lipid data in sleep apnoea.

Effects of recombinant human growth hormone administration on cardiovascular risk factors in obese children with relative growth hormone deficiency

Background

Based on the sample of obese children with relative growth hormone deficiency (GHD), the objective of our study was to determine the effects of rhGH treatment on cardiovascular risk factors, including body mass index (BMI), lipid levels and glucose metabolism index.

Methods

A total of 43 obese children with relative GHD were included in our final analysis. The obese subjects were divided into two groups: recombinant human growth hormone (rhGH) treatment group and untreated control group.

Results

After 6 months, subjects in the rhGH treatment group had significant reductions in BMI standard deviation scores (SDS) compared with controls (2.32 ± 0.85 vs. 2.80 ± 0.61; P = 0.041), and Insulin-like growth factor 1(IGF-1) level increased during rhGH treatment, in comparison with the control group (702.91 ± 246.03 vs. 348.30 ± 131.93 ng/mL, P < 0.001). GH treatment reduced low density lipoprotein cholesterol (LDL-C) (2.20 ± 0.45 vs. 2.63 ± 0.76 mmol/L, P = 0.027), aspartate aminotransferase (AST) (21.26 ± 5.72 vs. 32.30 ± 17.68 mmol/L, P = 0.006) as well as alanine aminotransferase (ALT) (16.70 ± 6.72 vs. 45.20 ± 46.62 mmol/L, P = 0.002), and increased high density lipoprotein cholesterol (HDL-C) (1.45 ± 0.40 vs. 1.19 ± 0.23 mmol/L, P = 0.016) levels compared with the control group.

Conclusion

RhGH treatment for 6 months on obese children with relative GHD reduces BMI SDS, stabilize IGF-1 levels, and exerts beneficial effects on blood lipid profiles and live enzyme compared with untreated control group. Moreover, GH administration has no significant effects on increased insulin resistance and no adversely effect on glucose homeostasis.

Recombinant bovine somatotropin on heifer’s biometric measures, bodyweight, blood metabolites, and dry matter intake predictions

This study aimed to determine the influence of sustained-release recombinant bovine somatotropin (rbST) injections on biometrics measures, bodyweight (BW), average BW gain, observed and predicted DM intake, accuracy of recent methods to estimate DM intake, blood metabolites, haematological profile and rectal temperature in dairy heifers. Thirty Holstein heifers (132 ± 27 kg BW and 6.2 ± 0.35 months of age) were used in a complete randomised design experiment. Heifers were assigned to treatments: (1) Control (CON), 250 mL of saline solution, or (2) rbST, 250 mg of sustained-release rbST every 15 days. Treatments were injected in the subcutaneous of ischiorectal fossa or subscapular region in a regular alternating manner (right and left side) every 15 days throughout a period of 90 days. Prediction of DM intake was calculated using either non-linear or linear models for heifers in tropical conditions. rbST injections increased the average values of thoracic perimeter, length, and rump width in heifers. rbST-treated heifers had higher average BW and BW gain than CON. Regardless of the model applied, both observed and predicted DM intake were higher for heifers rbST-treated in relation to CON. Non-linear model was accurate without significant bias. rbST injections elevated blood glucose and high-density lipoprotein cholesterol concentration in heifers. No differences were detected on haematological profile and rectal temperature of heifers. rbST injections every 15 days to growing heifers promoted animal performance by increasing biometrics measures and BW gain. In addition, non-linear model was accurate to predict DM intake of heifers.

Plasma biomarker proteins for detection of human growth hormone administration in athletes

Human growth hormone (GH) is a naturally occurring hormone secreted by the pituitary gland with anabolic and growth-promoting activities. Since an increased availability of recombinant GH (rGH) for the treatment of GH-deficient patients, GH has been abused in sports and it is prohibited. "GH-isoform" and "biomarkers" tests are currently available for detection of GH abuse in sports, however both methods suffer from shortcomings. Here, we report on a proteomic approach to search for novel protein biomarkers associated with rGH administration in non-elite athletes. In this study, participants received either placebo or rGH for 8 weeks, and were followed over a 6-week washout period. We used 2-D DIGE and iTRAQ LC-MS/MS analyses to expose rGH-dependent marker proteins. Eight rGH-dependent plasma proteins namely apolipoproptein-L1, alpha-HS-glycoprotein, vitamin D-binding protein, afamin, insulin-like growth factor-binding protein-3, insulin-like growth factor-binding protein-ALS, lumican and extracellular matrix proteins 1 were identified. Apolipoprotein L1 and alpha-HS-glycoprotein were validated by Western blots to confirm their identities and expression patterns in rGH- and placebo-treated subject cohorts. Independent confirmation of these putative GH-responsive biomarkers would be of value for clinical practices and may have sports anti-doping utility.

Mortality in adults with hypopituitarism: a systematic review and meta-analysis

PURPOSE

Hypopituitarism is a rare disorder with significant morbidity. To study the evidence on the association of premature mortality and hypopituitarism.

METHODS

A comprehensive search of multiple databases: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus was conducted through August, 2015. Eligible studies that evaluated patients with hypopituitarism and reported mortality estimates were selected following a predefined protocol. Reviewers, independently and in duplicate, extracted data and assessed the risk of bias.

RESULTS

We included 12 studies (published 1996-2015) that reported on 23,515 patients. Compared to the general population, hypopituitarism was associated with an overall excess mortality (weighted SMR of 1.55; 95 % CI 1.14-2.11), I ²  = 97.8 %, P = 0.000. Risk factors for increased mortality included younger age at diagnosis, female gender, diagnosis of craniopharyngioma, radiation therapy, transcranial surgery, diabetes insipidus and hypogonadism.

CONCLUSION

Hypopituitarism may be associated with premature mortality in adults. Risk is particularly higher in women and those diagnosed at a younger age.

Effects of low dose versus high dose human growth hormone on body composition and lipids in adults with GH deficiency: a meta-analysis of placebo-controlled randomized trials

PURPOSE

Doses of growth hormone in adults with growth hormone deficiency are now lower than previously. However, it is not clear they are as effective as higher doses. The objective of this meta-analysis was to assess efficacy of low to moderate dose (LD) GH replacement on standard endpoints of GH compared to higher doses.

METHODS

A meta-analysis was carried out using PubMed, Cochrane and Embase databases from 1960 to 9/23/12. Three reviewers identified randomized double-blind, placebo-controlled trials of 6 months duration. Of 173 publications, 28 representing 22 trials (591 GH-treated patients and 562 placebo) were included. Data were independently extracted by three reviewers. Endpoints were analyzed if ≥4 studies per dose group reported baseline and 6 month data.

RESULTS

Mean lean body mass (LBM) increased by 2.61 kg in GH-treated subjects versus 0.04 in the placebo group (P < 0.0001). Fat mass (FM) was reduced by -2.19 kg versus 0.31 (GH vs. placebo) (P = 0.0002). Changes in LBM and FM were dose-related (P = 0.02 and 0.007, respectively), high dose (HD) being more effective than low dose (LBM P = 0.03 and FM P = 0.04). In contrast, treatment with GH reduced total cholesterol -0.38 mmol/L versus. 0.01 (placebo) (P < 0.0001), and low density lipoprotein cholesterol (LDL-C) -0.42 mmol/L versus -0.1 (P = 0.0009), but there were no differences between LD and HD GH.

CONCLUSIONS

LDs of hGH improve total- and LDL-C, and body composition. Higher doses are more effective on body composition, but not lipids.

Serum lipoprotein (a) concentrations are inversely associated with T2D, prediabetes, and insulin resistance in a middle-aged and elderly Chinese population

Lipoprotein (a) [Lp(a)], an LDL-like particle, has been proposed as a causal risk factor for CVD among general populations. Meanwhile, both serum Lp(a) and diabetes increase the risk of CVD. However, the relationship between serum Lp(a) and T2D is poorly characterized, especially in the Asian population. Therefore, we conducted a cross-sectional study in 10,122 participants aged 40 years or older in Jiading District, Shanghai, China. Our study found that the prevalence of T2D was decreased from 20.9% to 15.0% from the lowest quartile to the highest quartile of serum Lp(a) concentrations (P for trend <0.0001). Logistic regression analyses showed that the odds ratios and 95% confidence intervals of prevalent T2D for quartiles 2-4 versus quartile 1 were 0.86 (0.73-1.01), 0.88 (0.75-1.04), and 0.76 (0.64-0.90) (P for trend = 0.0002), after adjustment for traditional confounding factors. Moreover, the risks for prevalent prediabetes, insulin resistance, and hyperinsulinemia were also decreased from the lowest to the top quartile. This inverse association between serum Lp(a) and T2D was not appreciably changed after we adjusted hypoglycemic medications or excluded the subjects with hypoglycemic and/or lipid-lowering agents and/or a history of self-reported CVD.

Evaluation of long-term pituitary functions in patients with severe ventricular arrhythmia: a pilot study

INTRODUCTION

Traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), stroke and cerebrovascular disease (CVD) are identified as risk factors for hypopituitarism. Pituitary dysfunction after TBI, SAH, and CVD may present in the acute phase or later in the course of the event. Chronic hypopituitarism, particularly growth hormone (GH) deficiency is related to the increased cardiovascular morbidity and mortality. In patients with serious ventricular arrhythmias, who need cardiopulmonary resuscitation, brain tissue is exposed to short-term severe ischemia and hypoxia. However, there are no data in the literature regarding pituitary dysfunction after ventricular arrhythmias.

PATIENTS AND METHODS

Forty-four patients with ventricular arrhythmias [ventricular tachycardia (VT), ventricular fibrillation (VF)] (mean age, 55.6 ± 1.8 years; 37 men, 7 women) were included in the study. The patients were evaluated after mean period of 21.2 ± 0.8 months from VT-VF. Basal hormone levels, including serum free triiodothyronine (fT3), free thyroxine (fT4), TSH, ACTH, prolactin, FSH, LH, total testosterone, estradiol, IGF-1, and cortisol levels were measured in all patients. To assess (GH)-insulin like growth factor-1 (IGF-1) axis, glucagon stimulation test was performed and 1 µg ACTH stimulation test was used for assessing hypothalamic-pituitary-adrenal (HPA) axis.

RESULTS

The frequencies of GH, gonadotropin and TSH deficiency were 27.2, 9.0, 2.2%, respectively. Mean IGF-1 levels were lower in GH deficiency group, but it was not statistically significant.

CONCLUSION

The present preliminary study showed that ventricular arrhythmias may result in hypopituitarism, particularly in growth hormone deficiency. Unrecognized hypopituitarism may be responsible for some of the cardiovascular problems at least in some patients.

Metabolic syndrome and cardiovascular risk among long-term survivors of acute lymphoblastic leukaemia - From the St. Jude Lifetime Cohort

Adult survivors of childhood acute lymphoblastic leukaemia (ALL) have a four-fold excess risk of mortality from cardiovascular disease. This cardiovascular risk has not been fully characterized. ALL survivors [n = 784, median age 31·7 years (18·9-59·1)] in the St. Jude Lifetime Cohort Study underwent evaluation for cardiovascular risk and metabolic syndrome (MetS) according to National Cholesterol Education Program - Adult Treatment Panel III criteria. Comparisons were made to 777 age-, sex-, and race-matched controls from the National Health and Nutrition Examination Survey (NHANES). MetS was identified in 259 survivors (33·6%) and associated with older age in 5-year increments (relative risk [RR] 1·13, 95% confidence interval [CI] 1·06-1·19) and prior cranial radiotherapy (CRT) (with craniospinal radiation: RR 1·88, 95%CI 1·32-2·67; without: RR 1·67, 95%CI 1·26-2·23). Measures of obesity were highly prevalent among female survivors and CRT recipients. Compared to NHANES controls, ALL survivors had a higher risk of MetS (RR 1·43, 95%CI 1·22-1·69), hypertension (RR 2·43, 95%CI 2·06-2·86), low high-density lipoprotein (RR 1·40, 95%CI 1·23-1·59), obesity (RR 1·47, 95%CI 1·29-1·68) and insulin resistance (1·64, 95%CI 1·44-1·86). This large study of clinically evaluated ALL survivors identified a high prevalence of MetS, obesity and cardiovascular risk, particularly in CRT recipients, underscoring the need for screening and aggressive reduction of modifiable risks.

Updates in growth hormone treatment and mortality

PURPOSE OF REVIEW

To review the literature with regard to mortality in patients with hypopituitarism with a focus on the role of growth hormone (GH) deficiency and therapy.

RECENT FINDINGS

Mortality is increased in hypopituitarism, particularly in female patients. In recent years mortality rates appear to be trending downwards towards that of the general population. Recent studies from retrospective or postmarketing surveillance studies have suggested that patients who receive GH therapy may not have increased mortality. Recent studies regarding mortality in paediatric patients treated with GH are conflicting and this area needs further study.

SUMMARY

There are several important limitations of available data regarding mortality in hypopituitarism and even more so in the impact of GH therapy, which need to be taken into account when interpreting the available data. The data regarding mortality in patients treated with GH as children is an area of much debate and will need further studies to clarify, given the conflicting reports in recent studies.

Lipoprotein(a): resurrected by genetics

Plasma lipoprotein(a) [Lp(a)] is a quantitative genetic trait with a very broad and skewed distribution, which is largely controlled by genetic variants at the LPA locus on chromosome 6q27. Based on genetic evidence provided by studies conducted over the last two decades, Lp(a) is currently considered to be the strongest genetic risk factor for coronary heart disease (CHD). The copy number variation of kringle IV in the LPA gene has been strongly associated with both Lp(a) levels in plasma and risk of CHD, thereby fulfilling the main criterion for causality in a Mendelian randomization approach. Alleles with a low kringle IV copy number that together have a population frequency of 25-35% are associated with a doubling of the relative risk for outcomes, which is exceptional in the field of complex genetic phenotypes. The recently identified binding of oxidized phospholipids to Lp(a) is considered as one of the possible mechanisms that may explain the pathogenicity of Lp(a). Drugs that have been shown to lower Lp(a) have pleiotropic effects on other CHD risk factors, and an improvement of cardiovascular endpoints is up to now lacking. However, it has been established in a proof of principle study that lowering of very high Lp(a) by apheresis in high-risk patients with already maximally reduced low-density lipoprotein cholesterol levels can dramatically reduce major coronary events.

Mortality in patients with pituitary disease

Pituitary disease is associated with increased mortality predominantly due to vascular disease. Control of cortisol secretion and GH hypersecretion (and cardiovascular risk factor reduction) is key in the reduction of mortality in patients with Cushing's disease and acromegaly, retrospectively. For patients with acromegaly, the role of IGF-I is less clear-cut. Confounding pituitary hormone deficiencies such as gonadotropins and particularly ACTH deficiency (with higher doses of hydrocortisone replacement) may have a detrimental effect on outcome in patients with pituitary disease. Pituitary radiotherapy is a further factor that has been associated with increased mortality (particularly cerebrovascular). Although standardized mortality ratios in pituitary disease are falling due to improved treatment, mortality for many conditions are still elevated above that of the general population, and therefore further measures are needed. Craniopharyngioma patients have a particularly increased risk of mortality as a result of the tumor itself and treatment to control tumor growth; this is a key area for future research in order to optimize the outcome for these patients.

Lipoprotein(a) and risk of type 2 diabetes

BACKGROUND

Previous studies have demonstrated that cardiovascular risk is higher with increased lipoprotein(a) [Lp(a)]. Whether Lp(a) concentration is related to type 2 diabetes is unclear.

METHODS

In 26 746 healthy US women (mean age 54.6 years), we prospectively examined baseline Lp(a) concentrations and incident type 2 diabetes (n = 1670) for a follow-up period of 13 years. We confirmed our findings in 9652 Danish men and women with prevalent diabetes (n = 419). Analyses were adjusted for risk factors that included age, race, smoking, hormone use, family history, blood pressure, body mass index, hemoglobin A(1c) (Hb A(1c)), C-reactive protein, and lipids.

RESULTS

Lp(a) was inversely associated with incident diabetes, with fully adjusted hazard ratios (HRs) and 95% CIs for quintiles 2-5 vs quintile 1 of 0.87 (0.75-1.01), 0.80 (0.68-0.93), 0.88 (0.76-1.02), and 0.78 (0.67-0.91); P for trend 0.002. The association was stronger in nonfasting women, for whom respective HRs were 0.79 (0.58-1.09), 0.78 (0.57-1.08), 0.66 (0.46-0.93), and 0.56 (0.40-0.80); P for trend 0.001; P for interaction with fasting status 0.002. When we used Lp(a) > or =10 mg/L and Hb A(1c) <5% as reference values, the adjusted HRs were 1.62 (0.91-2.89) for Lp(a) <10 mg/L and Hb A(1c) <5%, 3.50 (3.06-4.01) for Lp(a) > or =10 mg/L and Hb A(1c) 5%-<6.5%, and 5.36 (4.00-7.19) for Lp(a) <10 mg/L and Hb A(1c) 5%-<6.5%. Results were similar in nonfasting Danish men and women, for whom adjusted odds ratios were 0.75 (0.55-1.03), 0.64 (0.46-0.88), 0.74 (0.54-1.01), and 0.58 (0.42-0.79) for Lp(a) quintiles 2-5 vs quintile 1; P for trend 0.002.

CONCLUSIONS

Our results indicated that Lp(a) was associated inversely with risk of type 2 diabetes independently of risk factors, in contrast to prior findings of positive associations of Lp(a) with cardiovascular risk.

The metabolic syndrome in adult survivors of childhood cancer, a review

The number of adult survivors of childhood cancer in the general population has increased. As reports on the prevalence of the metabolic syndrome in adult survivors of childhood cancer are scarce, we reviewed the available literature on the components of the metabolic syndrome in adult survivors of childhood cancer. Although there is a lack of studies estimating the prevalence of metabolic syndrome directly, especially prevalence of insulin resistance, obesity, and dyslipidemia is increased in certain groups. Therefore, adult survivors of childhood cancer are at increased risk of developing cerebrovascular and cardiovascular diseases. Accordingly, it is important to identify the predisposing factors of the metabolic syndrome in cohorts of survivors, to introduce medical interventions, and to subsequently decrease the risk of cerebrovascular and cardiovascular events.

Changes in endothelial dysfunction and associated cardiovascular disease morbidity markers in GH-IGF axis pathology

Arterial endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and predisposes individuals to the deposition of unstable atherosclerotic plaques. It can also lead to increased arterial stiffness, which is an accepted cause of increased arterial pulse wave velocity (APWV). Endothelial dysfunction is reversed by recombinant human growth hormone (rhGH) therapy in patients with growth hormone (GH) deficiency (GHD), favorably influencing the risk for atherogenesis. Endogenous human growth hormone (hGH), secreted by the anterior pituitary, and levels of insulin-like growth factor-I (IGF-I), produced in response to hGH stimulation of the liver, peak during early adulthood, but decline throughout adulthood. It is suspected that low-grade inflammatory cardiovascular pathophysiologic markers such as homocysteine, nitric oxide, C-reactive protein (CRP), and fibrinogen and plasminogen activator inhibitor along with changes in lipid and glucose metabolism may all contribute to GHD-associated metabolic and cardiovascular complications. These effects are associated with increased APWV, but are attenuated by rhGH therapy in GHD. GH replacement increases IGF-I levels and reduces CRP and large-artery stiffness. Reviews of rhGH in the somatopause have not been overtly favorable. Whereas reviews of rhGH/rhIGF-I combinations in GH resistance are more positive than those for rhGH alone, their combined use in the somatopause is limited. Senescent individuals may benefit from such a combination.

[The influence of estrogen and progestogen replacement on growth hormone activity in women with hypopituitarism]

Treatment of hypogonadotropic hypogonadism in adult women with hypopituitarism can include a wide range of estrogen and progestogen treatment alternatives and oral administration is the route of least cost and greatest patient comfort. The oral estrogen route has a major impact on the growth hormone-insulin-like growth factor I (GH/IGF-1) axis. Oral estrogen therapy, when given concurrently with GH to patients with hypopituitarism, antagonizes the biological effects of GH treatment and aggravates the abnormalities of body composition and the metabolism in general. It is presumed that oral estrogen suppresses the secretion/production of IGF-1 by a hepatic first-pass mechanism, resulting in increased GH secretion by means of suppressing the IGF-1 negative feedback that is present in healthy women. This is clinically manifested in reduced lean body mass, increased fat mass, an atherogenic lipid profile and damage to psychological well-being. Some studies have indicated that progestogens with androgenic actions reverse the effect of reduced serum IGF-1 levels that is induced by the oral estrogens. Neutral progestogens do not exert this effect, however the stronger the androgenic potentialis, the more the effect of reduced IGF-1 will be reversed. This bibliographical review will deal with the clinical aspects of estrogen and progestogen replacement in women with hypopituitarism, their interactions with other hormone deficiencies and the impact of estrogen treatment on the metabolic actions of GH.

Long-term GH treatment of GH-deficient adults: comparison between one and two daily injections

The physiological pulsatile secretion of GH in humans might be important for the metabolic effects of GH. In the treatment of GH-deficient (GHD) patients, the most common regimen is a single sc injection at bedtime. It has not been completely established if this is the optimal mode of GH administration during long-term GH treatment. The aim of the present study was to evaluate the metabolic effects of two different GH replacement regimens comparing one to two daily injections. Eight men and six women, 42-78 yr old, with verified severe GHD, participated. Patients were matched for gender, age and body mass index (BMI) and were randomized to GH therapy (one or two injections daily) for 12 months. GH doses were individually titrated to IGF-I levels of age-matched controls. IGF-I, glucose, insulin, oral glucose tolerance test (OGTT), cholesterol, triglycerides, lipoproteins, including size fractionation with fast performance liquid chromatography, BMI and body composition were analyzed. After 12 months the median GH dose was 0.45 mg (range 0.25-0.50 mg) in both groups. Body fat had decreased by 20% (p<0.05) in the group receiving one daily GH injection. There were no differences between the two treatment groups in indices of carbohydrate or lipid metabolism. The administration of GH divided into two daily doses offered no major advantage as compared to the more convenient single injection in the evening. The GH-induced reduction in body fat occurred independently from changes in serum lipids.

Insulin-Like Growth Factor I Levels in Healthy Adults

Insulin-like growth factor I (IGF-I) levels mainly reflect secretion of growth hormone (GH) in the body. The aims of this study were to compare different IGF-I assay methods in healthy individuals, test the reliability of the methods and discuss the utility of IGF-I measurement in adults. The Nichols Institute Diagnostics radioimmunoassay was used to evaluate IGF-I in two random population samples of men and women (aged 25-64 years, n = 392) taken 10 years apart, in 1985 and 1995. This method for IGF-I testing was also compared with an immunoradiometric assay (IRMA) method in 387 men and women participating in the World Health Organization MONICA (MONItoring of trends and determinants for CArdiovascular diseases) Project, Goteborg, Sweden, in 1995. Serum IGF-I decreased with increasing age in both men and women. IGF-I was higher in young women compared with young men in both cohorts, while the opposite was found in the highest age group. Age-adjusted significant correlations were found between IGF-I and smoking, fibrinogen, coffee consumption, lipoprotein (a), osteocalcin and IGF-binding protein 3. The two cohorts showed similar mean IGF-I concentrations irrespective of method. The correlation between the Nichols and the IRMA methods was high: r = 0.93 (p < 0.0001). Based on this and previous studies, population-based IGF-I measurements are robust irrespective of which commercially available method of assay is used. IGF-I levels can be used in diagnosing acromegaly as well as providing target values. IGF-I assay can be used as a complement to stimulation testing in the diagnosis of GH deficiency, and as a tool for GH dose titration.

Estrogen regulation of growth hormone action

GH plays a pivotal role in regulating body growth and development, which is modulated by sex steroids. A close interplay between estrogen and GH leads to attainment of gender-specific body composition during puberty. The physiological basis of the interaction is not well understood. Most previous studies have focused on the effects of estrogen on GH secretion. There is also strong evidence that estrogen modulates GH action independent of secretion. Oral but not transdermal administration of estrogen impairs the metabolic action of GH in the liver, causing a fall in IGF-I production and fat oxidation. This results in a loss of lean tissue and a gain of body fat in postmenopausal women and an impairment of GH effect in hypopituitary women on GH replacement. The negative metabolic sequelae are potentially important because of the widespread use of oral estrogen and estrogen-related compounds. Estrogen affects GH action at the level of receptor expression and signaling. More recently, estrogen has been shown to inhibit Janus kinase/signal transducer and activator of transcription signaling by GH via the induction of suppressor of cytokine signaling-2, a protein inhibitor for cytokine signaling. This represents a novel paradigm of steroid regulation of cytokine receptors and is likely to have significance for a diverse range of cytokine function.

Recombinant GH replacement in hypopituitary adults improves endothelial cell function and reduces calculated absolute and relative coronary risk

OBJECTIVE

Adult GH deficiency (GHD) is linked to endothelial dysfunction and vascular disease. We examined the effect of 12 months of GH therapy on endothelial function, C-reactive protein (CRP) and coronary risk.

DESIGN

Open-design intervention study.

PATIENTS

Fourteen GH-deficient patients (nonsmokers, without diabetes, hypertension or vascular disease) studied before, 6 months and 12 months after GH therapy.

MEASUREMENTS

Flow-mediated dilatation (FMD), carotid intima-media thickness (IMT) thrombomodulin (TM), E-selectin, CRP, lipid profile, blood pressure and anthropometric data were recorded. We used the Framingham equation to calculate coronary risk.

RESULTS

FMD improved (7.5 +/- 1.62 vs. 11.93 +/- 1.52, P = 0.038). Overall there was no change in IMT, TM, E-selectin or CRP. The correlation between TM and FMD showed a trend for statistical significance (r = -0.54, P = 0.056). Changes in CRP correlated with change in IGF-1 (r = -0.67, P = 0.012); E-selectin correlated with high density lipoprotein (HDL)-cholesterol (r = -0.60, P = 0.028), triglycerides (r = 0.68, P = 0.01) and waist-to-hip ratio (WHR) (r = 0.71, P = 0.006). Systolic (127.36 +/- 4.47 vs. 120.36 +/- 3.50, P = 0.017) and diastolic (84.71 +/- 2.73 vs. 76.93 +/- 2.03, P = 0.005) blood pressure decreased. HDL-cholesterol increased (0.70 +/- 0.05 vs. 0.93 +/- 0.06, P = 0.001). WHR decreased (0.90 +/- 0.02 to 0.88 +/- 0.02, P = 0.043) without changes in weight or body mass index (BMI). Ten-year absolute (P = 0.009) and relative (P = 0.002) cardiac risk decreased.

CONCLUSION

Biophysical test of endothelial function (FMD) improved after 12 months of GH therapy but there was no significant change in biochemical endothelial or inflammatory markers. Calculated coronary risk decreased mainly due to reduction in systolic and diastolic blood pressure and increase in HDL-cholesterol.

Endocrine and metabolic aspects of adult Prader-Willi syndrome with special emphasis on the effect of growth hormone treatment

Prader-Willi syndrome (PWS) is a genetic disorder characterized by mild mental retardation, short stature, abnormal body composition, muscular hypotonia and distinctive behavioural features. Excessive eating causes progressive obesity with increased cardiovascular morbidity and mortality. In the PWS genotype loss of one or more normally active paternal genes in region q11-13 on chromosome 15 is seen. It is supposed that the genetic alteration leads to dysfunction of several hypothalamic centres and growth hormone (GH) deficiency (GHD) is common. PWS is well described in children, in whom GH treatment improves body composition, linear growth, physical strength and agility. Few studies have focused on adults. We examined a cohort of 19 young adults with clinical PWS (13 with positive genotype) and mean BMI of 35 kg/m2. At baseline the activity of the GH-insulin-like growth factor-I (IGF-I) system was impaired with low GH values, low total IGF-I and in relation to the obesity low levels of free IGF-I and non-suppressed IGF-binding-protein-1 (IGFBP-1). 2/3 were hypogonadal. Bone mineral density (BMD) was low. Four patients had impaired glucose tolerance and nine patients high homeostasis model assessment (HOMA) index, indicating insulin resistance. Seven patients had a moderate dyslipidemia. The 13 patients with the PWS genotype were shorter and had significantly lower IGF-I. Seventeen (9 men and 8 women), subsequently completed a 12 months GH treatment trial, and GH had beneficial effects on body composition without significant adverse effects. The effects were more pronounced in the patients with the PWS genotype. Analysis of peptides involved in appetite regulation showed that leptin levels were high reflecting obesity and as a consequence NPY levels were low. In relation to the patients obesity circulating oxytocin levels were abnormally low and ghrelin levels abnormally high. Thus, oxytocin and ghrelin might be involved in the hyperphagia. NPY, leptin and ghrelin did not change during GH treatment. In conclusion this pilot study showed that adults with PWS have a partial GH deficiency, and GH treatment has beneficial effects on body composition in adult PWS without significant side-effects. Larger and longer term studies on the effect of GH replacement in adult PWS are encouraged.

Long-Term Challenges in Growth Hormone Treatment

Growth hormone deficiency (GHD) is defined biochemically as a response to hypoglycaemia with a peak GH concentration of less than 5 microg/l. The 'GHD syndrome' is a range of psychological and physical symptoms that are associated with GHD, which include increased central adiposity, decreased bone mineral density, abnormal lipid profiles, decreased cardiovascular performance, reduced lean body mass (LBM), social isolation, depressed mood and increased anxiety. Importantly, the combination of physical and psychological problems can often result in a reduced quality of life. A number of trials have shown that GH replacement therapy can lead to a substantial improvement in GHD associated symptoms. Following up to 12 months of treatment with GH, LBM increased, left ventricular systolic function improved and the mean volume of adipose tissue fell. After only 4 months of treatment, a rise in exercise capacity was recorded, and after 2 years' treatment, isokinetic and isometric muscle strength had normalized in proximal muscle groups. Feelings of well-being and vitality also improved significantly. However, studies on the effects of treatment on insulin sensitivity in GH-deficient patients have had conflicting results. In this paper, we will discuss the long-term consequences of GHD and the effects of GH replacement therapy.

Hypercholesterolemia and obesity in adult patients with hypopituitarism: a report of a nation-wide survey in Japan

Dyslipidemia and obesity are common in adult patients with hypopituitarism. Possible contributions of age, sex and hormone deficiencies to hypercholesterolemia and obesity in adult hypopituitary patients were analyzed in 1, 272 Japanese cases based on a database of a national survey on adult hypopituitarism. In patients on routine hormone replacement therapy, 30.5% of male and 40.7% of female subjects were considered hypercholesterolemic. In univariate analysis, hypercholesterolemia was more prevalent in female, aged, untreated Gn-deficient and TSH-deficient groups. In multivariate analysis, sex of female, age older than 40 yr and TSH deficiency were the independent contributing factors to hypercholesterolemia. Obesity (body mass index (BMI) > or = 25 kg/m2) was more prevalent in male, TSH-deficient and ADH-deficient groups. Severe obesity (BMI > or = 30) was observed in high prevalence in the youngest group. These findings suggest that hypercholesterolemia and obesity were prevalent in different age and gender groups in Japanese adult patients with hypopituitarism. Insufficient replacement of thyroid hormone and possibly gonadotropin deficiency might contribute to hypercholesterolemia. In contrast, hypothalamic dysfunction as well as hormone deficiencies might play roles in obesity in these patients.

Growth hormone (GH) replacement in GH-deficient adults: a crossover trial comparing the effect on metabolic control, well-being and compliance of three injections per week versus daily injections

Growth hormone (GH) replacement therapy regimens in adults using daily subcutaneous (sc) injections may not be optimal with respect to carbohydrate and lipid metabolism. The aim of this study was to compare the efficacy of three times weekly injections with daily sc GH injections in terms of serum IGF-I, IGFBPs, lipoprotein levels, serum bone markers, glucose metabolism, body composition, compliance and well-being. Twenty hypopituitary men, 46-76 years, on a course of stable conventional GH replacement therapy for more than 12 months, were included in a 16-week crossover trial. During the first 8 weeks GH was administered three times per week followed by 8 weeks with daily sc injections with the same weekly dose of GH. Fasting serum samples were collected at baseline and on two consecutive days at the end of each 8-week period. Serum IGF-I and IGFBP-3 concentrations were lower both the first and second morning after the last injection during the period with three injections per week. The second morning after the last GH injection in this period the IGF-I/BP-3 ratio, plasma insulin and FFA were lower whereas IGFBP-1 was increased as compared with values obtained during the period with daily injections. Serum Lp(a) levels, body composition, fat distribution, well-being and compliance were not differently affected by the two treatment regimens. These results suggest that the same weekly dose of GH given as three injections per week reduces serum IGF-I and IGFBP-3 levels without affecting Lp(a) levels. The day-to-day variation in glucose metabolism and FFA serum levels differs considerably between the two modes of GH administration.

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.

Effects of short- and long-term growth hormone replacement on lipoprotein composition and on very-low-density lipoprotein and low-density lipoprotein apolipoprotein B100 kinetics in growth hormone-deficient hypopituitary subjects

In this study, we concurrently examined the effects of 8 and 40 weeks of growth hormone replacement (GHR) on lipids, lipoprotein composition, low-density lipoprotein (LDL) size, very-low-density lipoprotein (VLDL) apolipoprotein (apo)B kinetics and LDL apoB kinetics. Eight weeks of GHR did not alter lipid profiles. Forty weeks of GHR increased high-density lipoprotein-cholesterol (HDL-C) concentration (P =.01), nonsignificantly reduced LDL-C (P =.06), and reduced the HDL/LDL-C ratio (P =.04). Forty weeks of GHR increased HDL free cholesterol (P =.03), total cholesterol (P =.01), and cholesterol ester (P <.01) concentrations. No other significant changes in VLDL, LDL, or HDL composition or LDL size were noted at any time. Eight weeks of GHR reduced VLDL apoB absolute secretion rate (ASR, P =.03), with nonsignificant reductions in fractional secretion rate (FSR, P =.09) and pool size (P =.09). After 40 weeks of GHR, the VLDL apoB ASR, FSR, and pool size were not significantly different from baseline. Forty weeks of GHR increased both LDL apoB FSR (P =.02) and LDL apoB ASR (P =.04), with a small decrease in pool size. Thus, GHR may have important antiatherogenic effects; HDL-C increased, LDL-C was nonsignificantly reduced, the total/HDL-C ratio was reduced, VLDL apoB production was reduced, and LDL apoB turnover was increased.

Long-Term Efficacy and Safety of Somatropin for Adult Growth Hormone Deficiency

The beneficial effects of somatropin (growth hormone [GH] replacement therapy) in adults are now established. Long-term somatropin administration in GH-deficient adults improves body composition, muscle strength, quality of life, bone mass and density, and lipoprotein pattern. The extent to which somatropin therapy can also reduce cardiovascular morbidity and mortality in GH-deficient adults remains to be determined. By starting with a low dose of somatropin, which is gradually increased based on clinical response (body composition, well-being, and serum insulin-like growth factor-1 concentration), effective treatment can be achieved with a minimum of fluid-related adverse effects. Thorough long-term monitoring of glucose metabolism, cardiovascular measurements, and underlying pituitary disease, is, however, mandatory.

Growth hormone deficiency and vascular risk

The importance of growth hormone deficiency (GHD) in adult life has become more apparent over the last decade. As well as a distinct clinical syndrome there is a significant excess risk of cardiovascular disease. Although it is difficult to ascertain what part is played by the original pituitary disorder and the concomitant replacement hormonal therapies, there is clear evidence that GHD is associated with known cardiovascular risk factors such as body shape, lipid profile, insulin resistance, blood pressure, vessel wall morphology and haemostatic factors. Novel means of assessing vascular risk such as pulse wave velocity and flow-mediated dilatation can also estimate the risk without invasive procedures. The role of possible mediators of endothelial function such as nitric oxide and free radicals is being investigated further. Replacement of GH in GH-deficient patients leads to many effects on the above indices, some but not all of which are associated with reduced vascular risk. Long-term follow-up studies of morbidity and mortality are required for an accurate assessment of the beneficial effects of therapy.

Low-dose GH replacement improves the adverse lipid profile associated with the adult GH deficiency syndrome

OBJECTIVE

Adult growth hormone deficiency (AGHD) is associated with an adverse lipid profile. The majority of previous studies of GH replacement have used supraphysiological doses and reported favourable changes in the lipid profile. Whether this beneficial effect is the result of pharmacological GH therapy, or occurs in response to low-dose GH replacement aimed at normalization of the serum IGF-I, has not been fully elucidated.

STUDY DESIGN

We studied 67 patients with GH deficiency using a low-dose individualized GH replacement regimen. GH was commenced at a dose of 0.27 mg/day and the GH dose titrated until the serum IGF-I was normalized. Serum lipids were assessed at baseline, 12 and 24 months.

RESULTS

A reduction in total cholesterol (TC) was observed at 12 (6.01 vs. 5.77 mmol, P = 0.04) and 24 months (6.01 vs. 5.56, P = 0.09). The reduction in LDLC failed to reach significance at 12 months (3.97 vs. 3.8, P = 0.09), but was significant at 24 months (3.97 vs. 3.50, P = 0.02). Levels of HDLC did not change significantly at 12 or 24 months. Significant improvements in the TC/HDLC ratio were observed at both 12 (5.68 vs. 5.29, P = 0.01) and 24 months (5.68 vs. 4.86, P = 0.007). A significant fall in triglycerides (TG) was present at 12 months (2.07 vs. 1.83, P = 0.01), and was maintained at 24 months, but was no longer significant (2.07 vs. 1.89, P = 0.28). At 12 months there was no correlation between improvements in lipid parameters and either the change in IGF-I SD score or the GH dose. Using multivariate analysis the change in TC, LDLC and the TC/HDLC ratio with 12 months GH replacement were determined by the baseline TC, LDLC and TC/HDLC levels (R2 = 0.18, P = 0.004; R2 = 0.20, P = 0.006; and R2 = 0.33, P < 0.0001), respectively.

CONCLUSIONS

Low-dose individualized GH replacement aimed at normalization of the serum IGF-I is associated with significant improvements in TC, LDLC, TGs and the TC/HDLC ratio. The greatest improvements are observed in patients with the most adverse lipid profiles at baseline. Improvements are independent of changes in the IGF-I SDS and GH dose.

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.