Context. Serum resistin concentration is increased in patients with nonalcoholic fatty liver disease (NAFLD) in proportion with the histological severity of the disease, but the relevance of the contribution of fatty liver per se is undetermined.

Objective. To assess the relationship between serum resistin and the degree of ectopic fat accumulation in vivo in humans.

Design and Setting. The intra-hepatic fat (IHF) content, measured quantitatively by means of ¹H-Magnetic Resonance Spectroscopy (MRS), serum resistin and biochemical and hormonal metabolic correlates of fatty liver and insulin resistance were assessed in 28 affected patients and 47 individuals with comparable anthropometric features served as controls. Insulin sensitivity was estimated using the computer HOMA-2. A subset of volunteers (n = 18) also underwent ¹H-MRS of the calf muscles to assess the intramyocellular lipid content (IMCL).

Results. In patients with fatty liver the IHF content (13 ± 8 vs. 2 ± 1% ww; P < 0.0001) and also the soleus IMCL content (P < 0.05) were increased in comparison with the controls. Patients with fatty liver had lower insulin sensitivity (HOMA2-%S: 59 ± 24 vs. 72 ± 29%; P < 0.04), serum resistin (3.4 ± 0.8 vs. 3.9 ± 1.0 ng/ml; P < 0.02) and adiponectin (P < 0.01) concentrations. Serum resistin was inversely correlated with the IHF content (r=-0.35; P < 0.003) and the soleus IMCL content (r=-0.51; P < 0.05), but not with HOMA2-%S.

Conclusion. This study demonstrates that excessive ectopic fat accumulation in the liver and skeletal muscle of insulin resistant subjects is associated with lower serum resistin concentration and not with hyper-resistinemia.