Intracellular lipid content of liver and skeletal muscle in patients with adult growth hormone deficiency without diabetes mellitus

Background: Insulin resistance (IR) and visceral obesity are often observed in adult growth hormone deficiency patients (AGHDs). However, there is little information regarding the intrahepatic lipid (IHL) or the intramyocellular lipid (IMCL) content and their association with IR in AGHDs. The aim of this study was to directly assess IHL and IMCL in AGHDs by proton magnetic resonance spectroscopy and to evaluate the association of lipid levels with IR. Methods: Appropriate hormone replacement therapy (RT) other than GH and estrogen was prescribed before evaluation. Ten AGHDs (aged 23-75 years) without diabetes or elevation of aminotransferases were examined the percent body fat, visceral fat area (VFA), IHL, IMCL, adipokines and glucose metabolism. In two AGHDs, changes of these parameters were evaluated after GHRT. Results: Visceral obesity and metabolic syndrome was found in 100% and in 80% of the patients, respectively. IHL was significantly higher than that in non-obese healthy controls (12.5 ± 4.6 vs. 0.69 ± 0.46%, M ± SE, p = 0.0330), while IMCL did not differ between AGHDs and controls (528.8 ± 137.2 vs. 378 ± 51.1 mM, p = 0.2728). Homeostasis model assessment of IR was significantly correlated with IHL (r = 0.896, p = 0.0001) and IMCL (r = 0.749, p = 0.0102), but not with the VFA or percent truncal fat mass. A decrease of IHL and improvement of glucose tolerance were observed in the two patients after 6 M GHRT. Conclusion: These results demonstrated that IHL, but not IMCL, may increase in AGHDs, and that IHL may associate with IR. GHRT may decrease IHL along with amelioration of IR.