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

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.

Long-term depot specific changes in adipose tissue after treatment of acromegaly

CONTEXT

Patients with active acromegaly present a decreased adipose tissue (AT) mass, and short-term studies show that treatment leads to AT depot-specific gain. However, it remains unclear if the increase is persistent in the long-term perspective and/or is sex-dependent.

DESIGN

To characterize the depot-specific changes of AT after treatment of acromegaly and identify contributing factors.

METHODS

Adipose tissue, including visceral (VAT), subcutaneous (SAT), and total (TAT), and android to gynoid ratio (A/G ratio) were measured by dual energy X-ray absorptiometry at diagnosis (n = 62), and after treatment at short-term (median (IQR) 1.9 (1.5-2.3)) and long-term 5.5 (3.9-9.5) years, and correlated to clinical and biochemical measurements. Growth hormone (GH), insulin-like growth factor 1 (IGF-1), glucose and HbA1c levels, gonadal status, and the presence of diabetes mellitus were recorded. Remission status was assessed at the long-term visit (IGF-1/ULN ≤ 1.3). Differences in the temporal course of AT from baseline to short- and long-term follow-up according to sex, diabetes, gonadal, and remission status were evaluated by mixed model analysis, adjusted for age.

RESULTS

Despite a stable body mass index, VAT and A/G ratio increased at both time points, whereas SAT mainly increased at short-term, plateauing afterwards (P < .05 for all). Visceral adipose tissue and A/G ratio were higher in men (P = .035 and P < .001), and the A/G ratio increased more than in women (P = .003). Glucose and HbA1c decreased short-term (P < .05) and remained stable at long-term. The increase in AT depots correlated with the decrease of disease activity at long-term. Remission status had no effect on changes in AT mass during follow-up.

CONCLUSION

Treatment of acromegaly leads to an increase in AT mass in a depot- and sex-specific manner both at short-term and long-term follow-up. Glucose metabolism improves rapidly after disease control and persists.

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.