Body Composition and Ectopic Lipid Changes With Biochemical Control of Acromegaly

An Overview of Cardiovascular Risk in Pituitary Disorders

Cardiovascular comorbidities owing to hormonal excess or deficiency are the main cause of mortality in patients with pituitary disorders. In patients with Cushing's Disease, there is an increased prevalence of cardiovascular diseases and/or risk factors including visceral obesity, insulin resistance, atherosclerosis, arterial hypertension, dyslipidaemia, hypercoagulability as well as structural and functional changes in the heart, like cardiac hypertrophy and left ventricle (LV) dysfunction. Notably, these demonstrate limited reversibility even after remission. Furthermore, patients with acromegaly may manifest insulin resistance but also structural and functional heart changes, also known as "acromegalic cardiomyopathy". Patients with prolactinomas demonstrate an aggravation of metabolic parameters, obesity, dysregulation of glucose and lipid metabolism as well as endothelial dysfunction. Hypopituitarism and conventional hormonal replacement therapy may also contribute to an unhealthy metabolic status, which promotes atherosclerosis and may lead to premature mortality. This review discusses the literature on cardiovascular risk in patients with pituitary disorders to increase physician awareness regarding this aspect of management in patients with pituitary disorders.

Temporal and masseter muscle evaluation by MRI provides information on muscle mass and quality in acromegaly patients

PURPOSE

The impact of GH/IGF-1 levels on skeletal muscle in acromegaly is still controversial. Temporal (TMT) and masseter muscle (MMT) thickness has been recently demonstrated as a reliable measure of muscle mass. We aimed to investigate the relationship between TMT, MMT and clinical/biochemical characteristics in patients with acromegaly.

METHODS

Single center retrospective longitudinal study including 69 patients with at least one available brain/sella turcica MRI and matched clinical data. TMT, MMT, and muscle fatty infiltration (modified Goutallier score) were evaluated in all patients at baseline (first available MRI) and over time (182 MRIs analyzed).

RESULTS

At baseline, both TMT and MMT were higher in males than females (p = 0.001 and p = 0.016, respectively). TMT and MMT were positively associated (β 0.508, p < 0.001), and they were positively correlated with IGF-1 xULN (TMT, p = 0.047; MMT, p = 0.001). MMT had a positive correlation with patients' weight (p = 0.015) and height (p = 0.006). No correlation was found between TMT, MMT and the presence of hypogonadism. Considering all available MRIs, sex and IGF-1 xULN were significant determinants of TMT and MMT at multivariable analysis (female sex: β -0.345/-0.426, p < 0.001; IGF-1 xULN: β 0.257/0.328, p < 0.001). At longitudinal evaluation, uncontrolled patients at baseline showed a significant reduction of MMT over time (p = 0.044). Remarkable fatty infiltration was observed in 34-37% of MRIs; age was the main determinant (temporal muscle: OR 1.665; p = 0.013; masseter muscle: OR 1.793; p = 0.009).

CONCLUSION

Male patients with higher IGF-1 values have thicker temporal and masseter muscles, suggesting that sex and IGF-1 have a significant impact on muscle mass in acromegaly.

Quantitative ultrasound techniques and biochemical markers to assess liver steatosis and fibrosis in newly diagnosed acromegaly

PURPOSE

The liver is known to be protected from steatosis under the influence of high GH/IGF-1. Cytokeratin 18 (CK18) and insulin-like growth factor binding protein 7 (IGFBP7) increase in liver steatosis and fibrosis. The aim of this study was to use quantitative ultrasound techniques and biochemical markers to assess liver steatosis and liver fibrosis in newly diagnosed acromegaly.

METHODS

This single-center, cross-sectional study included 23 patients with newly diagnosed acromegaly and 46 age, sex, body mass index (BMI) and waist circumference (WC)-matched controls. Liver steatosis was assessed using tissue attenuation imaging (TAI), and stiffness, indicative of fibrosis, was assessed by shear wave elastography (SWE). Serum IGFBP7 and CK18 were studied by ELISA.

RESULTS

The acromegaly group had significantly lower liver steatosis (p = 0.006) and higher liver stiffness (p = 0.004), serum IGFBP7 (p = 0.048) and CK18 (p = 0.005) levels than the control group. The presence of fibrosis (p = 0.012) was significantly higher in the acromegaly group than in the control group. Moreover, CK18 was positively correlated with liver stiffness, WC, HOMA-IR, HbA1c, and triglyceride. In the acromegaly group, liver steatosis was negatively correlated with GH level. Stepwise multiple linear regression analysis revealed that BMI (p = 0.008) and CK18 (p = 0.015) were independent risk factors for increased liver stiffness.

CONCLUSION

This study showed that there was an increased presence of liver fibrosis independent of liver steatosis in newly diagnosed acromegaly. Serum CK18 appears to be a potential marker of increased liver fibrosis in acromegaly.

Skeletal Muscle Evaluation in Patients With Acromegaly

Context

Patients with acromegaly are characterized by chronic exposure to high growth hormone (GH) and insulin-like growth factor-1 levels, known for their anabolic effect on skeletal muscle. Therefore, an increased skeletal muscle mass could be hypothesized in these individuals. Herein, we have performed a systematic revision of published evidence regarding skeletal muscle mass, quality, and performance in patients with acromegaly.

Evidence Acquisition

A systematic review of the literature in the PubMed database up to September 1, 2023, was conducted with the following query: acromegaly AND ("muscle mass" OR "skeletal muscle"). We excluded studies that did not compare different disease states or used nonradiological methods for the skeletal muscle analyses, except for bioelectrical impedance analysis.

Evidence Synthesis

Fifteen studies met the inclusion criteria. A total of 360 patients were evaluated for skeletal muscle mass, 122 for muscle fatty atrophy, and 192 for muscle performance. No clear evidence of increased skeletal muscle mass in patients with active disease compared to control or healthy individuals emerged. As for skeletal muscle quality, we observed a trend toward higher fatty infiltration among patients with acromegaly compared to healthy participants. Likewise, patients with active disease showed consistently worse physical performance compared to control or healthy individuals.

Conclusion

Skeletal muscle in acromegaly has lower quality and performance compared to that of healthy individuals. The small number of published studies and multiple confounding factors (eg, use of different radiological techniques) contributed to mixed results, especially regarding skeletal muscle mass. Well-designed prospective studies are needed to investigate skeletal muscle mass in patients with acromegaly.

Nonalcoholic Fatty Liver Disease, Liver Fibrosis, and Utility of Noninvasive Scores in Patients With Acromegaly

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is a metabolical disorder and can lead to liver fibrosis. Because it is commonly seen, several noninvasive scores (NS) have been validated to identify high-risk patients. Patients with NAFLD have been shown to have higher serum angiopoietin-like protein-8 (ANGPTL-8) levels.

OBJECTIVE

The risk of NAFLD is known insufficiently in acromegaly. Moreover, the utility of the NS and the link between NAFLD and ANGPTL-8 in acromegaly is unknown.

METHODS

Thirty-two patients with acromegaly (n = 15, active [AA] and n = 17, controlled acromegaly [CA]) and 19 healthy controls were included. Magnetic resonance imaging (MRI)-proton density fat fraction (PDFF) was used to evaluate hepatic steatosis, and magnetic resonance elastography to evaluate liver stiffness measurement. ANGPTL-8 levels were measured with ELISA.

RESULTS

Median liver MRI-PDFF and NAFLD prevalence in AA were lower than in CA (P = .026 and P < .001, respectively). Median magnetic resonance elastography-liver stiffness measurement were similar across groups. Of the NS, visceral adiposity index, fatty liver index, hepatic steatosis index, and triglyceride-glucose index (TyG) all showed positive correlation with the liver MRI-PDFF in the control group. However, only TyG significantly correlated with liver fat in the AA and CA groups. There was no correlation between traditional NAFLD risk factors (body mass index, waist circumference, C-reactive protein, homeostasis model assessment for insulin resistance, visceral adipose tissue) and liver MRI-PDFF in the AA and CA. Patients with acromegaly with NAFLD had lower GH, IGF-1, and ANGPTL-8 levels than in those without NAFLD (P = .025, P = .011, and P = .036, respectively).

CONCLUSION

Active acromegaly may protect from NAFLD because of high GH. In patients with acromegaly, NAFLD risk cannot be explained with classical risk factors; hence, additional risk factors must be identified. TyG is the best score to evaluate NAFLD risk. Lower ANGPTL-8 in patients with acromegaly and NAFLD implies this hormone may be raised because of insulin resistance rather than being a cause for NAFLD.

Acromegalic Cardiomyopathy: An Entity on its own? The Effects of GH and IGF-I Excess and Treatment on Cardiovascular Risk Factors

Acromegaly is a chronic disease resulting from constantly elevated concentrations of growth hormone (GH) and insulin-like growth factor I (IGF-I). If not adequately treated, GH and IGF-I excess is associated with various cardiovascular risk factors. These symptoms mainly include hypertension and impaired glucose metabolism, which can be observed in approximately one-third of patients. Other comorbidities are dyslipidemia and the presence of obstructive sleep apnea syndrome. However, even in the absence of conventional cardiovascular risk factors, myocardial hypertrophy can occur, which reflects the impact of GH and IGF-I excess itself on the myocardium and is defined as acromegalic cardiomyopathy. Whereas previous echocardiography-based studies reported a high prevalence of cardiomyopathy, this prevalence is much lower in cardiac magnetic resonance imaging-based studies. Myocardial hypertrophy in acromegaly is due to a homogeneous increase in the intracellular myocardial mass and extracellular myocardial matrix and improves following successful treatment through intracellular changes. Intramyocardial water retention or ectopic lipid accumulation might not be of relevant concern. Successful treatment significantly improves myocardial morphology, as well as cardiovascular risk factors. In addition to GH/IGF-I-lowering therapy, the diagnosis and treatment of cardiovascular complications is crucial for the successful management of acromegaly.

Endocrine aspects of metabolic dysfunction-associated steatotic liver disease (MASLD): Beyond insulin resistance

While the association of metabolic dysfunction-associated steatotic liver disease (MASLD) with obesity and insulin resistance is widely appreciated, there are a host of complex interactions between the liver and other endocrine axes. While it can be difficult to definitively distinguish direct causal relationships and those attributable to increased adipocyte mass, there is substantial evidence of the direct and indirect effects of endocrine dysregulation on the severity of MASLD, with strong evidence that low levels of growth hormone, sex hormones, and thyroid hormone promote the development and progression of disease. The impact of steroid hormones, e.g. cortisol and dehydroepiandrosterone, and adipokines is much more divergent. Thoughtful assessment, based on individual risk factors and findings, and management of non-insulin endocrine axes is essential in the evaluation and management of MASLD. Multiple therapeutic options have emerged that leverage various endocrine axes to reduce the fibroinflammatory cascade in MASH.

Age, body composition parameters and glycaemic control contribute to trabecular bone score deterioration in acromegaly more than disease activity

Introduction

Impairment of bone structure in patients with acromegaly (AP) varies independently of bone mineral density (BMD). Body composition parameters, which are altered in patients with acromegaly, are important determinants of bone strength.

Purpose

The aim of this study was to examine BMD and lumbar trabecular bone score (TBS) by dual-energy X-ray absorptiometry (DXA) and to assess its relationship with disease activity, age, glucose metabolism, and body composition parameters.

Methods

This cross-sectional prospective study involved 115 patients with acromegaly (70 F, 45 M) and 78 healthy controls (CON) (53 F, 25 M) matched for age, gender, and BMI. Bone mineral density, TBS and body composition parameters were measured using DXA.

Results

AP presented with lower TBS compared to CON (1.2 ± 0.1 v 1.31 ± 0.1, P< 0.001). No significant correlation was observed between IGF-1/GH levels and TBS. Age, glycated haemoglobin, BMI, waist circumference, fat mass, and lean mass negatively correlated with TBS in both sexes. Multiple linear regression analysis of all these parameters revealed age and waist circumference as independent significant predictors of TBS in AP. We did not find difference in BMD (lumbar and femoral sites) between AP and CON nor between active and controlled AP. We observed negative correlation between age and BMD of the femoral neck and total hip (P < 0.001). Testosterone levels in males, BMI, waist circumference, fat mass, and lean mass positively correlated with BMD in AP, with stronger correlation between lean mass and BMD compared to fat mass.

Conclusion

Patients with acromegaly have lower TBS than controls, confirming impaired bone microarchitecture in acromegaly regardless of BMD. Age, body composition parameters and glucose metabolism contribute to TBS deterioration in AP more than disease activity itself.

Growth hormone and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a prevalent cause of liver disease and metabolic comorbidities. Obesity is strongly associated with NAFLD and is also a state of relative deficiency of growth hormone (GH). Evidence supports a role of reduced GH and insulin-like growth factor-1 (IGF-1) in NAFLD pathogenesis. Physiological actions of GH in the liver include suppression of de novo lipogenesis (DNL) and promotion of lipid beta-oxidation, and GH also appears to have anti-inflammatory actions. Physiologic actions of IGF-1 include suppression of inflammatory and fibrogenic pathways important in the evolution from steatosis to steatohepatitis and fibrosis. Rodent models of impaired hepatic GH signaling show the development of steatosis, sometimes accompanied by inflammation, hepatocellular damage, and fibrosis, and these changes are ameliorated by treatment with GH and/or IGF-1. In humans, individuals with GH deficiency and GH resistance demonstrate an increased prevalence of NAFLD compared to controls, with improvement in hepatic lipid, steatohepatitis, and fibrosis following GH replacement. As a corollary, individuals with GH excess demonstrate lower hepatic lipid compared to controls along with increased hepatic lipid following treatment to normalize GH levels. Clinical trials demonstrate that augmentation of GH reduces hepatic lipid content in individuals with NAFLD and may also ameliorate steatohepatitis and fibrosis. Taken together, evidence supports an important role for perturbations in the GH/IGF-1 axis as one of the pathogenic mechanisms of NAFLD and suggests that further study is needed to assess whether augmentation of GH and/or IGF-1 may be a safe and effective therapeutic strategy for NAFLD.

Metabolomics in acromegaly: a systematic review

The therapeutic response heterogeneity in acromegaly persists, despite the medical-surgical advances of recent years. Thus, personalized medicine implementation, which focuses on each patient, is justified. Metabolomics would decipher the molecular mechanisms underlying the therapeutic response heterogeneity. Identification of altered metabolic pathways would open new horizons in the therapeutic management of acromegaly. This research aimed to evaluate the metabolomic profile in acromegaly and metabolomics' contributions to understanding disease pathogenesis. A systematic review was carried out by querying four electronic databases and evaluating patients with acromegaly through metabolomic techniques. In all, 21 studies containing 362 patients were eligible. Choline, the ubiquitous metabolite identified in growth hormone (GH)-secreting pituitary adenomas (Pas) by in vivo magnetic resonance spectroscopy (MRS), negatively correlated with somatostatin receptors type 2 expression and positively correlated with magnetic resonance imaging T2 signal and Ki-67 index. Moreover, elevated choline and choline/creatine ratio differentiated between sparsely and densely granulated GH-secreting PAs. MRS detected low hepatic lipid content in active acromegaly, which increased after disease control. The panel of metabolites of acromegaly deciphered by mass spectrometry (MS)-based techniques mainly included amino acids (especially branched-chain amino acids and taurine), glyceric acid, and lipids. The most altered pathways in acromegaly were the metabolism of glucose (particularly the downregulation of the pentose phosphate pathway), linoleic acid, sphingolipids, glycerophospholipids, arginine/proline, and taurine/hypotaurine. Matrix-assisted laser desorption/ionization coupled with MS imaging confirmed the functional nature of GH-secreting PAs and accurately discriminated PAs from healthy pituitary tissue.

IGF-1 is positively associated with BMI in patients with acromegaly

PURPOSE

Acromegaly is a disorder characterized by IGF-1 excess due to autonomous GH secretion. In individuals without acromegaly, IGF-1 is not only influenced by GH secretion but is also sensitive to other factors including nutritional status, as evidenced by the inverted U-shaped association between BMI and IGF-1; in low-weight individuals (BMI < 18.5 kg/m²) and those who are obese, IGF-1 levels may be frankly low. It is not known if this same relationship between BMI and IGF-1 is also observed in acromegaly.

METHODS

Retrospective study including patients who underwent resection of a pituitary adenoma (n = 197) for either acromegaly (n = 32) or a nonfunctioning adenoma (NFPA, n = 165) at a large academic medical center between 1/1/2015 and 5/31/2021.

RESULTS

Median BMI in acromegaly was 30.8 kg/m² (range 20.9-42.6 kg/m²). Percent upper limit of normal (%ULN) IGF-1 was 228.2% [159.0, 271.4] in acromegaly versus 32.2% [18.5, 50] in NFPA (p < 0.0001). There was a significant positive association between BMI and %ULN IGF-1 (R = 0.35, p < 0.05) in acromegaly. In contrast, there was no association between BMI and %ULN IGF-1 in the NFPA group as a whole (p = 0.22), but a significant inverse association between BMI and %ULN IGF-1 in NFPA patients with a BMI ≥ 35 kg/m² (rho =  - 0.39, p = 0.02).

CONCLUSION

In contrast to individuals without acromegaly, BMI is significantly and positively associated with IGF-1 in acromegaly across the weight spectrum. Future studies are needed to determine if obese patients with acromegaly experience more significant symptoms related to their disease, or if patients with a low BMI may require different diagnostic criteria.

Long-term Outcome of Body Composition, Ectopic Lipid, and Insulin Resistance Changes With Surgical Treatment of Acromegaly

Context

Acromegaly presents a unique pattern of lower adiposity and insulin resistance in active disease but reduction in insulin resistance despite a rise in adiposity after surgery. Depot-specific adipose tissue masses and ectopic lipid are important predictors of insulin resistance in other populations, but whether they are in acromegaly is unknown. Long-term persistence of body composition changes after surgery is unknown.

Objective

To determine how depot-specific body composition and ectopic lipid relate to insulin resistance in active acromegaly and whether their changes with surgery are sustained long-term.

Methods

Cross-sectional study in patients with active acromegaly and longitudinal study in newly diagnosed patients studied before and in long-term follow-up, 3 (1-8) years (median, range), after surgery. Seventy-one patients with active acromegaly studied cross-sectionally and 28 with newly diagnosed acromegaly studied longitudinally. Main outcome measures were visceral (VAT), subcutaneous (SAT), and intermuscular adipose tissue masses by whole-body magnetic resonance imaging; intrahepatic lipid (IHL) by proton magnetic resonance spectroscopy; insulin resistance measures derived from fasting; and oral glucose tolerance test insulin and glucose levels.

Results

SAT and insulin-like growth factor 1 level, but not VAT or IHL, were independent predictors of insulin resistance in active acromegaly. VAT, SAT, and IHL gains were sustained long-term after surgery. VAT mass rise with surgery correlated inversely with rise in QUICKI while SAT rise correlated with fall in the Homeostatic Model Assessment score.

Conclusion

SAT and disease activity are important predictors of insulin resistance in active acromegaly. Adiposity gains are sustained long-term after surgical treatment and impact on the accompanying improvement in insulin resistance.

Filling the gap between the heart and the body in acromegaly: a case-control study

OBJECTIVE

Cardiovascul diseases are the most common comorbidities in acromegaly. Potential parameters in pathology of cardiovascular comorbidities are changes in levels of growth hormone (GH) and insulin-like growth factor 1 (IGF-1) as well as body composition parameters.

PURPOSE

The aim of this study was to examine morphological and functional parameters of the cardiovascular system by echocardiography and to assess its relationship with disease activity and body composition parameters.

METHODS

We prospectively enroled 129 acromegalic patients (82 females, 47 males) and 80 healthy controls (53 females, 27 males) matched for age, gender, and BMI. All patients underwent two-dimensional echocardiography. Body composition parameters were assessed by dual-energy X-ray absorptiometry.

RESULTS

Acromegaly patients presented with higher left ventricle mass (LVM) compared to controls (LVMI: 123 ± 45 g/m² vs 83 ± 16 g/m², P < 0.001). Prevalence of left ventricle hypertrophy in acromegaly patients was 67% (78% concentric, 22% eccentric). IGF -1 levels, BMI, and lean mass positively correlated with LVM in all acromegaly patients (P < 0.001). Fat mass positively correlated with LVM in females (R = 0.306, P = 0.005), but this correlation was not found in males. We did not find any difference in size of the left and right ventricle between acromegaly patients and controls. Acromegaly patients presented with left atrium enlargement, diastolic dysfunction and low incidence of systolic dysfunction. Valvopathy was found in 43% of patients with predominant (31%) prevalence of mitral regurgitation.

CONCLUSION

Our study demonstrates higher prevalence of cardiovascular comorbidities in acromegaly patients and the impact of IGF-1 levels and body composition parameters in pathology in some of these comorbidities.

Ectopic lipid deposition and insulin resistance in patients with GH disorders before and after treatment

OBJECTIVES

Insulin resistance is associated with ectopic lipid deposition. Growth hormone (GH) status also modulates ectopic lipid accumulation, but how this associates with insulin resistance in patients with GH disorders is not well established.

DESIGN AND METHODS

Twenty-one patients diagnosed with acromegaly and 12 patients with adult GH deficiency (GHD) were studied at diagnosis and after treatment. A reference group of 12 subjects was included. Each study day comprised assessment of body composition with dual-energy X-ray absorptiometry, ectopic lipid deposition in the liver by MR spectroscopy, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

Disease control of acromegaly decreased lean body mass (LBM) (P < .000) and increased the percentage of total body fat (TBF) (P < .000). GH replacement increased LBM in the GHD patients (P = .007) and decreased the percentage of TBF (P = .010). The intrahepatic lipid (IHL) content increased after disease control in acromegaly (P = .004), whereas IHL did not change significantly after GH replacement in GHD (P = .34). Insulin resistance (HOMA-IR) improved after disease control of acromegaly (P < .000) and remained unaltered after GH replacement in the GHD patients (P = .829).

CONCLUSIONS

GH status is a significant modulator of body composition and insulin sensitivity.GH excess reduces total fat mass and intrahepatic lipid content together with induction of insulin resistance.The data support the notion that GH-induced insulin resistance is unassociated with hepatic lipid accumulation.

Understanding the role of growth hormone in situations of metabolic stress

Growth hormone (GH) is secreted by the anterior pituitary gland and plays a key role in controlling tissue and body growth. While basal GH secretion is considerably reduced along adulthood and aging, several situations of metabolic stress can lead to robust increases in circulating GH levels. The objective of the present review is to summarize and discuss the importance of GH regulating different physiological functions in situations of metabolic stress, including prolonged food restriction, hypoglycemia, exercise, pregnancy, and obesity. The presented data indicate that GH increases hunger perception/food intake, fat mobilization, blood glucose levels, and insulin resistance and produces changes in energy expenditure and neuroendocrine responses during metabolic challenges. When all these effects are considered in the context of situations of metabolic stress, they contribute to restore homeostasis by (1) helping the organism to use appropriate energy substrates, (2) preventing hypoglycemia or increasing the availability of glucose, (3) stimulating feeding to provide nutrients in response to energy-demanding activities or to accelerate the recovery of energy stores, and (4) affecting the activity of neuronal populations involved in the control of metabolism and stress response. Thus, the central and peripheral effects of GH coordinate multiple adaptations during situations of metabolic stress that ultimately help the organism restore homeostasis, increasing the chances of survival.

Acromegaly: pathogenesis, diagnosis, and management

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

Metabolic actions of the growth hormone-insulin growth factor-1 axis and its interaction with the central nervous system

The growth hormone/insulin growth factor-1 axis is a key endocrine system that exerts profound effects on metabolism by its actions on different peripheral tissues but also in the brain. Growth hormone together with insulin growth factor-1 perform metabolic adjustments, including regulation of food intake, energy expenditure, and glycemia. The dysregulation of this hepatic axis leads to different metabolic disorders including obesity, type 2 diabetes or liver disease. In this review, we discuss how the growth hormone/insulin growth factor-1 axis regulates metabolism and its interactions with the central nervous system. Finally, we state our vision for possible therapeutic uses of compounds based in the components of this hepatic axis.

The acromegaly lipodystrophy

Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are essential to normal growth, metabolism, and body composition, but in acromegaly, excesses of these hormones strikingly alter them. In recent years, the use of modern methodologies to assess body composition in patients with acromegaly has revealed novel aspects of the acromegaly phenotype. In particular, acromegaly presents a unique pattern of body composition changes in the setting of insulin resistance that we propose herein to be considered an acromegaly-specific lipodystrophy. The lipodystrophy, initiated by a distinctive GH-driven adipose tissue dysregulation, features insulin resistance in the setting of reduced visceral adipose tissue (VAT) mass and intra-hepatic lipid (IHL) but with lipid redistribution, resulting in ectopic lipid deposition in muscle. With recovery of the lipodystrophy, adipose tissue mass, especially that of VAT and IHL, rises, but insulin resistance is lessened. Abnormalities of adipose tissue adipokines may play a role in the disordered adipose tissue metabolism and insulin resistance of the lipodystrophy. The orexigenic hormone ghrelin and peptide Agouti-related peptide may also be affected by active acromegaly as well as variably by acromegaly therapies, which may contribute to the lipodystrophy. Understanding the pathophysiology of the lipodystrophy and how acromegaly therapies differentially reverse its features may be important to optimizing the long-term outcome for patients with this disease. This perspective describes evidence in support of this acromegaly lipodystrophy model and its relevance to acromegaly pathophysiology and the treatment of patients with acromegaly.

The GH/IGF-1 Axis Is Associated With Intrahepatic Lipid Content and Hepatocellular Damage in Overweight/Obesity

CONTEXT

Obesity is a state of relative growth hormone (GH) deficiency, and GH has been identified as a candidate disease-modifying target in nonalcoholic fatty liver disease (NAFLD) because of its lipolytic and anti-inflammatory properties. However, the GH/IGF-1 axis has not been well characterized in NAFLD.

OBJECTIVE

We aimed to investigate serum GH and IGF-1 levels in relation to intrahepatic lipid content (IHL) and markers of hepatocellular damage and fibrosis in NAFLD.

METHODS

This cross-sectional study included 102 adults (43% women; age 19-67; BMI ≥ 25 kg/m2) without type 2 diabetes. IHL was measured by magnetic resonance spectroscopy; NAFLD was defined by ≥ 5% IHL. Peak-stimulated GH in response to GH releasing hormone and arginine was assessed as was serum IGF-1 (LC/MS).

RESULTS

There was no difference in mean age, BMI, or sex distribution in NAFLD vs controls. Mean (± SD) IHL was higher in NAFLD vs controls (21.8 ± 13.3% vs 2.9 ± 1.1%, P < 0.0001). Mean peak-stimulated GH was lower in NAFLD vs controls (9.0 ± 6.3 vs 15.4 ± 11.2 ng/mL, P = 0.003), including after controlling for age, sex, visceral adipose tissue, and fasting glucose. In a stepwise model, peak-stimulated GH predicted 14.6% of the variability in IHL (P = 0.004). Higher peak-stimulated GH was also associated with lower ALT. Higher serum IGF-1 levels were associated with lower risk of liver fibrosis by Fibrosis-4 scores.

CONCLUSION

Individuals with NAFLD have lower peak-stimulated GH levels but similar IGF-1 levels as compared to controls. Higher peak-stimulated GH levels are associated with lower IHL and less hepatocellular damage. Higher IGF-1 levels are associated with more favorable fibrosis risk scores. These data implicate GH and IGF-1 as potential disease modifiers in the development and progression of NAFLD.

Growth Hormone and Insulin-Like Growth Factor 1 Regulation of Nonalcoholic Fatty Liver Disease

Patients with obesity have a high prevalence of nonalcoholic fatty liver disease (NAFLD), representing a spectrum of simple steatosis to nonalcoholic steatohepatitis (NASH), without and with fibrosis. Understanding the etiology of NAFLD is clinically relevant since NAFLD is an independent risk factor for diabetes and cardiovascular disease. In addition, NASH predisposes patients to the development of cirrhosis and hepatocellular carcinoma, and NASH cirrhosis represents the fastest growing indication for liver transplantation in the United States. It is appreciated that multiple factors are involved in the development and progression of NAFLD. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) regulate metabolic, immune, and hepatic stellate cell function, and alterations in the production and function of GH is associated with obesity and NAFLD/NASH. Therefore, this review will focus on the potential role of GH and IGF1 in the regulation of hepatic steatosis, inflammation, and fibrosis.

Changes in Cross-Sectional Area of the Median Nerve and Body Composition Parameters after Treatment of Acromegaly: 1 year Follow-Up

OBJECTIVE

Median neuropathy is a common manifestation of acromegaly, although its pathology is uncertain. Changes in levels of growth hormone (GH) and insulin-like growth factor I (IGF-I) and body composition are potential parameters in pathology of median neuropathy in acromegaly. We aimed to assess changes in the cross-sectional area (CSA) of the median nerve and body composition in newly diagnosed acromegalic patients 1 year after treatment and to determine their mutual relationships.

DESIGN

This prospective study included 30 patients with newly diagnosed acromegaly and 30 healthy controls matched for age, gender, and body mass index. Physical and laboratory examinations, dual-energy X-ray absorptiometry (DXA), and ultrasound evaluations were performed at baseline and 1 year after initial treatment.

RESULTS

The CSA of the median nerve was increased in acromegalic patients compared with controls (13.1 mm² [12.2-14.9] vs 7.5 mm² [6.4-8.4], P < 0.001). One year after treatment of acromegaly, GH and IGF-I levels decreased significantly. The median nerve CSA was significantly reduced after treatment (11.6 mm² [10.2-13.1], P < 0.001). Reduction of IGF-I levels correlated with a decrease in lean mass and increase in fat mass. The median nerve CSA positively correlated with IGF-I levels (R = 0.492, P=0.006) and lean mass (R = 0.419, P=0.021) in acromegalic patients before treatment.

CONCLUSION

This study demonstrates a reduction in the median nerve CSA 1 year after treatment of acromegaly. These changes are closely associated with a reduction in IGF- I levels and in lean body mass. The enlargement of the median nerve in acromegaly can be reversed with adequate treatment.

Diabetes Mellitus Predicts Weight Gain After Surgery in Patients With Acromegaly

OBJECTIVE

Metabolic complications are common in patients with acromegaly. However, this occasionally does not improve post-surgery and may be related to postoperative weight gain. We aimed to investigate the postoperative weight change and factors associated with postoperative weight gain in patients with acromegaly.

DESIGN AND METHODS

Overall, 113 consecutive patients with body weight records pre- and 3-6 months post-surgery between October 2009 and March 2021 were enrolled. Patients were divided into three groups: weight loss (weight decrease ≥3%), stable, and weight gain (weight increase ≥3%). Hormone status, metabolic comorbidities, and anthropometric parameters were compared between the groups.

RESULTS

Among 113 patients, 29 (25.7%) and 26 (23.0%) patients lost and gained weight, respectively, post-surgery. There were no significant differences in baseline characteristics, including age at diagnosis, sex, body mass index, and growth hormone levels among the three groups. The prevalence of diabetes mellitus at diagnosis was significantly higher in the weight gain group than in the other groups. Patients with diabetes (n=22) had a 5.2-fold higher risk of postoperative weight gain than those with normal glucose tolerance (n=37) (P=0.006). In the diabetes mellitus group, the percentage lean mass decreased (-4.5 [-6.6-2.0]%, P=0.002), and the percentage fat mass significantly increased post-surgery (18.0 [4.6-36.6]%, P=0.003), whereas the normal glucose tolerance group did not show body composition changes post-surgery.

CONCLUSION

In patients with acromegaly, 23% experienced ≥3% weight gain post-surgery. Diabetes mellitus at diagnosis is a significant predictor of weight and fat gain post-surgery.

[Hepatopulmonary syndrome: a rare manifestation of cirrhosis in patient with diencephalic obesity and nonalcoholic fatty liver disease after surgery for craniopharyngioma]

We describe a 15-year girl, who developed panhypopituitarism and diencephalic obesity after surgical excision of craniopharyngioma, followed by nonalcoholic fatty liver disease and cirrhosis 5 years after surgery. Cirrhosis in this case manifested by hypoxia due to hepatopulmonary syndrome, and despite cure of craniopharyngioma by surgery and radiosurgery treatment and adequate hormonal substitution therapy patient died 9 years after surgery. Growth hormone substitutional therapy in patients with hypopituitarism, and steatohepatitis may decrease liver triglyceride accumulation and prevent end-stage liver disease.

Body Composition Changes with Long-term Pegvisomant Therapy of Acromegaly

Context

In active acromegaly, the lipolytic and insulin antagonistic effects of growth hormone (GH) excess alter adipose tissue (AT) deposition, reduce body fat, and increase insulin resistance. This pattern reverses with surgical therapy. Pegvisomant treats acromegaly by blocking GH receptor (GHR) signal transduction and lowering insulin-like growth factor 1 (IGF-1) levels. The long-term effects of GHR antagonist treatment of acromegaly on body composition have not been studied.

Methods

We prospectively studied 21 patients with active acromegaly who were starting pegvisomant. Body composition was examined by whole body magnetic resonance imaging, proton magnetic resonance spectroscopy of liver and muscle and dual-energy x-ray absorptiometry, and endocrine and metabolic markers were measured before and serially during 1.0 to 13.4 years of pegvisomant therapy. The data of patients with acromegaly were compared with predicted and to matched controls.

Results

Mass of visceral AT (VAT) increased to a peak of 187% (1.56-229%) (P < .001) and subcutaneous AT (SAT) to 109% (–17% to 57%) (P = .04) of baseline. These remained persistently and stably increased, but did not differ from predicted during long-term pegvisomant therapy. Intrahepatic lipid rose from 1.75% to 3.04 % (P = .04). Although lean tissue mass decreased significantly, skeletal muscle (SM) did not change. IGF-1 levels normalized, and homeostasis model assessment insulin resistance and HbA1C were lowered.

Conclusion

Long-term pegvisomant therapy is accompanied by increases in VAT and SAT mass that do not differ from predicted, stable SM mass and improvements in glucose metabolism. Long-term pegvisomant therapy does not produce a GH deficiency-like pattern of body composition change.

Associations between circulating bone-derived hormones lipocalin 2, osteocalcin, and glucose metabolism in acromegaly

PURPOSE

The aim was to examine changes in the bone-derived hormone lipocalin 2 (LCN2) levels in patients with active acromegaly and to investigate the potential roles of LCN2 and osteocalcin in glucose metabolism.

METHODS

We recruited 50 consecutive acromegalic patients. Of those, 39 patients with complete postoperative follow-up data were included. Thirty sex-, age-, and BMI-matched healthy individuals were recruited as normal controls. The pre- and postoperative serum LCN2 and osteocalcin levels were compared. The homeostasis model assessment insulin resistance (HOMA-IR) index and secretion [β-cell function (HOMA-β)] were calculated.

RESULTS

Compared with controls, acromegalic subjects had lower LCN2 levels (34.15 ± 9.95 vs 57.50 ± 29.75 ng/mL, P < 0.01) and higher osteocalcin levels (55.45 ± 34.02 vs 19.46 ± 6.69 ng/mL, P < 0.01). Acromegalic patients also had elevated HOMA-IR levels, and the HOMA-β and the area under the curve for insulin (AUC INS) levels were slightly but nonsignificantly increased. The serum levels of LCN2 significantly increased after surgery (37.03 ± 9.73 vs 45.15 ± 15.33 ng/mL, P < 0.05), and those of osteocalcin significantly decreased [43.51 (26.73-65.66) vs 24.79 (18.39-32.59) ng/mL, P < 0.01]. Total lean mass was the only positive predictor of LCN2, and elevated serum IGF-I was a positive predictor of osteocalcin. Low LCN2 and elevated serum osteocalcin levels were predictors of the AUC INS, and osteocalcin was a positive predictor of HOMA-β.

CONCLUSION

The bone-derived hormones, osteocalcin and LCN2 changed significantly in active acromegaly, were altered after treatment and served as predictors of β-cell function in acromegaly. This study shows that the bone could be involved in regulating glucose metabolism in acromegaly.

Semen quality in hypogonadal acromegalic patients

OBJECTIVE

Growth hormone (GH) activity might be implicated in male reproductive function. One previous study has suggested significantly reduced semen quality in untreated acromegalic patients due to both reduced sperm counts and sperm motility.

DESIGN AND METHODS

A retrospective study comprising ten uncontrolled hypogonadal acromegalic patients (median age 29 years) who delivered semen for cryopreservation before initiation of testosterone therapy. Semen variables and hormone concentrations were compared to those of ten non-acromegalic hypogonadal men with pituitary disease (age 31 years) and those of young healthy men.

RESULTS

Acromegalic patients vs. non-acromegalic patients had a higher percentage of progressive motile spermatozoa (62 vs. 47%, p = 0.04). Eight of ten acromegalic patients and 82% of controls had total sperm counts above 39 million and progressive motile spermatozoa above 32% (p = 0.55), corresponding to the WHO 2010 reference levels for expected normal fertility for these variables. Non-acromegalic patients vs. healthy controls had reduced percentage of progressive motile spermatozoa (47 vs. 57%, p = 0.02) and only five of ten patients had semen quality above the WHO reference level, which was significantly lower than observed in healthy controls (p = 0.022). Total sperm counts were similar between both patient groups and controls. There were no differences in reproductive hormone levels between acromegalic patients vs. non-acromegalic patients (p-values between 0.10 and 0.61). Compared to healthy controls both patient groups had severely reduced serum testosterone, calculated free testosterone.

CONCLUSIONS

Despite severe hypoandrogenism acromegalic patients had semen quality similar to healthy controls based on determination of the number of progressively motile spermatozoa. By contrast non-acromegalic pituitary patients had reduced sperm motility. Our data do not support reduced semen quality in acromegaly.

A Consensus on the Diagnosis and Treatment of Acromegaly Comorbidities: An Update

OBJECTIVE

The aim of the Acromegaly Consensus Group was to revise and update the consensus on diagnosis and treatment of acromegaly comorbidities last published in 2013.

PARTICIPANTS

The Consensus Group, convened by 11 Steering Committee members, consisted of 45 experts in the medical and surgical management of acromegaly. The authors received no corporate funding or remuneration.

EVIDENCE

This evidence-based consensus was developed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence following critical discussion of the current literature on the diagnosis and treatment of acromegaly comorbidities.

CONSENSUS PROCESS

Acromegaly Consensus Group participants conducted comprehensive literature searches for English-language papers on selected topics, reviewed brief presentations on each topic, and discussed current practice and recommendations in breakout groups. Consensus recommendations were developed based on all presentations and discussions. Members of the Scientific Committee graded the quality of the supporting evidence and the consensus recommendations using the GRADE system.

CONCLUSIONS

Evidence-based approach consensus recommendations address important clinical issues regarding multidisciplinary management of acromegaly-related cardiovascular, endocrine, metabolic, and oncologic comorbidities, sleep apnea, and bone and joint disorders and their sequelae, as well as their effects on quality of life and mortality.

Increased ATP synthesis might counteract hepatic lipid accumulation in acromegaly

Patients with active acromegaly (ACRO) exhibit low hepatocellular lipids (HCL), despite pronounced insulin resistance (IR). This contrasts the strong association of IR with nonalcoholic fatty liver disease in the general population. Since low HCL levels in ACRO might be caused by changes in oxidative substrate metabolism, we investigated mitochondrial activity and plasma metabolomics/lipidomics in active ACRO. Fifteen subjects with ACRO and seventeen healthy controls, matched for age, BMI, sex, and body composition, underwent 31P/1H-7-T MR spectroscopy of the liver and skeletal muscle as well as plasma metabolomic profiling and an oral glucose tolerance test. Subjects with ACRO showed significantly lower HCL levels, but the ATP synthesis rate was significantly increased compared with that in controls. Furthermore, a decreased ratio of unsaturated-to-saturated intrahepatocellular fatty acids was found in subjects with ACRO. Within assessed plasma lipids, lipidomics, and metabolomics, decreased carnitine species also indicated increased mitochondrial activity. We therefore concluded that excess of growth hormone (GH) in humans counteracts HCL accumulation by increased hepatic ATP synthesis. This was accompanied by a decreased ratio of unsaturated-to-saturated lipids in hepatocytes and by a metabolomic profile, reflecting the increase in mitochondrial activity. Thus, these findings help to better understanding of GH-regulated antisteatotic pathways and provide a better insight into potentially novel therapeutic targets for treating NAFLD.

The effects of growth hormone on adipose tissue: old observations, new mechanisms

The ability of growth hormone (GH) to induce adipose tissue lipolysis has been known for over five decades; however, the molecular mechanisms that mediate this effect and the ability of GH to inhibit insulin-stimulated glucose uptake have scarcely been documented. In this same time frame, our understanding of adipose tissue has evolved to reveal a complex structure with distinct types of adipocyte, depot-specific differences, a biologically significant extracellular matrix and important endocrine properties mediated by adipokines. All these aforementioned features, in turn, can influence lipolysis. In this Review, we provide a historical and current overview of the lipolytic effect of GH in humans, mice and cultured cells. More globally, we explain lipolysis in terms of GH-induced intracellular signalling and its effect on obesity, insulin resistance and lipotoxicity. In this regard, findings that define molecular mechanisms by which GH induces lipolysis are described. Finally, data are presented for the differential effect of GH on specific adipose tissue depots and on distinct classes of metabolically active adipocytes. Together, these cellular, animal and human studies reveal novel cellular phenotypes and molecular pathways regulating the metabolic effects of GH on adipose tissue.

Fibroblast Activation Protein is a GH Target: A Prospective Study of Patients with Acromegaly Before and After Treatment

BACKGROUND

Fibroblast growth factor 21 (FGF21) is a circulating hormone with pleiotropic metabolic effects, which is inactivated by fibroblast activation protein (FAP). Data regarding interaction between FGF21, FAP, and growth hormone (GH) are limited, but it is noteworthy that collagens are also FAP substrates, since GH potently stimulates collagen turnover.

AIM

To measure circulating FGF21 components, including FAP, in patients with acromegaly before and after disease control.

METHODS

Eighteen patients with active acromegaly were studied at the time of diagnosis and ≥ 6 months after disease control by either surgery or medical treatment. Serum levels of total and active FGF21, β-klotho, FAP, and collagen turnover markers were measured by immunoassays. Expression of putative FGF21-dependent genes were measured in adipose tissue by reverse transcriptase-polymerase chain reaction, body composition assessed by dual-energy x-ray absorptiometry scan, and insulin sensitivity estimated with homeostatic model assessment of insulin resistance (HOMA-IR).

RESULTS

Total FGF21, active FGF21 and β-klotho remained unchanged. Insulin sensitivity and body fat mass increased after disease control but neither correlated with active FGF21. Expression of FGF21-dependent genes did not change after treatment. FAP levels (µg/L) were markedly reduced after treatment [105.6 ± 29.4 vs 62.2 ± 32.4, P < 0.000]. Collagen turnover markers also declined significantly after treatment and ΔFAP correlated positively with ΔProcollagen Type I (P < 0.000) and Type III (P < 0.000).

CONCLUSION

1) Circulating FGF21 and β-klotho do not change in response to acromegaly treatment, 2) FAP concentrations in serum decrease after disease control and correlate positively with collagen turnover markers, and 3) FAP is a hitherto unrecognized GH target linked to collagen turnover.

CLINICAL TRIALS REGISTRATION

NCT00647179.

Pasireotide-LAR in acromegaly patients treated with a combination therapy: a real-life study

PURPOSE

Little data are available regarding the safety and efficacy of switching to Pasireotide-LAR monotherapy in acromegaly patients with partial resistance to first-generation somatostatin agonists (1gSRL) who require combination treatment with cabergoline or pegvisomant.

METHOD

In this monocentric prospective study within a tertiary university hospital, 15 consecutive acromegalic adults partially resistant to 1gSRL treated with octreotide LAR or lanreotide SR, and cabergoline (n = 4, 3.5 mg/week) or pegvisomant (n = 11, median dose 100 mg/week), were switched to Pasireotide-LAR (8 with 40 mg/month; 7 with 60 mg/month). Immunohistochemical expression level of SSTR5 and the granulation pattern of nine somatotroph adenomas were retrospectively determined to test for a correlation with the therapeutic efficacy of Pasireotide-LAR.

RESULTS

Median IGF-1 concentration at the first evaluation (median 3 months) was similar to baseline (1.0 vs 1.1 ULN). 11/15 patients had IGF-1 levels ≤1.3 ULN before and after the switch but individual changes were variable. Hyperglycemia was frequent and greater in diabetic patients. 7/15 patients stopped Pasireotide-LAR due to lack of control of IGF-1 or intolerance. 8/15 patients received Pasireotide-LAR for a median of 29 months with IGF-1 levels ≤1.3 ULN and acceptable glucose tolerance (median HbA1c 6.1%). Two patients required initiation of oral antidiabetic treatment. The intensity of SSTR5 expression and the granulation pattern of adenomas were of limited value for the prediction of Pasireotide-LAR effectiveness.

CONCLUSION

Pasireotide-LAR may represent a suitable therapeutic alternative in a subset of acromegalic patients requiring combination therapy involving a 1gSRL.

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.

The effectiveness of a therapist-oriented home rehabilitation program for a patient with acromegaly: A case study

BACKGROUND

Acromegaly causes numerous functional limitations that negatively impact patients' performance of activities of daily living (ADLs) and contribute to the deterioration of health-related quality of life (HRQoL). Thus, the purpose of the present case study was to evaluate the effect of therapist-oriented home rehabilitation (TOHR) for a patient with acromegaly.

CASE DESCRIPTION

We report the case of a 53-year-old man who was diagnosed with primary acromegaly 17 years ago. He complained of difficulties performing tasks that involved his hands, pain in the lower limbs, and fatigue when he climbed a few flights of stairs. Although he performed ADLs independently, he reported some difficulties or discomfort when performing them.

INTERVENTION AND OUTCOME

The patient underwent a booklet-guided physical exercise program that lasted two months (three times per week, 60 minutes per session). The activities included overall stretching, muscle strengthening, and endurance exercises, along with aerobic conditioning through functional circuit training. After two months of exercise, he reported improved HRQoL as assessed with the Acromegaly Quality of Life Questionnaire, with increases in quadriceps muscle strength and 6-min walking distance. However, none of these benefits remained when the patient was assessed after a 1-month washout period.

CONCLUSION

This study showed that patients with acromegaly may benefit markedly from TOHR, which could provide a novel therapeutic approach as an adjunct to hormone control therapy.

Insulin Resistance in Patients With Acromegaly

Acromegaly is characterized by chronic overproduction of growth hormone (GH) that leads to insulin resistance, glucose intolerance and, ultimately, diabetes. The GH-induced sustained stimulation of lipolysis plays a major role not only in the development of insulin resistance and prediabetes/diabetes, but also in the reduction of lipid accumulation, making acromegaly a unique case of severe insulin resistance in the presence of reduced body fat. In the present review, we elucidate the effects of GH hypersecretion on metabolic organs, describing the pathophysiology of impaired glucose tolerance in acromegaly, as well as the impact of acromegaly-specific therapies on glucose metabolism. In addition, we highlight the role of insulin resistance in the development of acromegaly-associated complications such as hypertension, cardiac disease, sleep apnea, polycystic ovaries, bone disease, and cancer. Taken together, insulin resistance is an important metabolic hallmark of acromegaly, which is strongly related to disease activity, the development of comorbidities, and might even impact the response to drugs used in the treatment of acromegaly.

Dynamic changes in the distribution of facial and abdominal adipose tissue correlated with surgical treatment in acromegaly

PURPOSE

Acromegaly is a systemic metabolic disease. Growth hormone (GH) have a significant impact on adipose tissue (AT). A huge reduction of serum GH after surgical treatment may cause substantial AT redistribution. The objective of this study was to illustrate the dynamic changes in distribution of facial and abdominal AT correlated with surgical treatment in patients with acromegaly.

METHODS

Abdominal AT in 17 acromegaly patients (group 1) was studied longitudinally preoperatively and 1 month to 1 year postoperatively. The facial and abdominal subcutaneous AT (fSAT and aSAT) of another 17 acromegaly patients (group 2) were compared with 7 nonfunctional pituitary adenoma (NFPA) controls. The areas of fSAT, aSAT, and visceral adipose tissue (VAT) were obtained by MRI and quantified by image analysis software, and intrahepatic lipid (IHL) was assessed by 1H magnetic resonance spectroscopy (MRS).

RESULTS

Abdominal adipose tissue (aSAT, VAT, and IHL) increased overall after surgical treatment. However, IHL first decreased and then continuously increased during the follow-up. Compared with the increased amount of aSAT, the fSAT amount decreased after surgical treatment. The inconsistency of this phenomenon did not appear in the NFPA control subjects.

CONCLUSION

The perioperative dynamic distribution of the facial and abdominal fat in acromegaly revealed regional differences in the intricate effect of GH on adipose tissue. Reduction of serum GH after surgical treatment of acromegaly was associated with dynamic increases of IHL, abdominal visceral, and subcutaneous fat, but a reduction of facial subcutaneous fat.