Distinguishing nonalcoholic steatohepatitis from fatty liver: serum-free fatty acids, insulin resistance, and serum lipoproteins

Objectives: The prognosis of nonalcoholic fatty liver disease is determined by liver biopsy; steatohepatitis can be progressive whereas fatty liver is benign. Insulin resistance and increased hepatic-free fatty acids are central to the pathophysiology of this disorder. Our objective was to assess whether serum-free fatty acids, lipoproteins, and insulin resistance are increased in steatohepatitis compared with fatty liver and healthy controls, and thus may be potential noninvasive markers for liver disease severity. Methods: Fifteen subjects with biopsy proven nonalcoholic steatohepatitis, 15 with histological fatty liver, and 15 healthy controls were enrolled. Fasting serum glucose and insulin levels, serum-free fatty acids, HDL, LDL, and cholesterol were collected from each subject. Insulin resistance was calculated using the homeostasis assessment model. Results: Insulin resistance, LDL, and cholesterol-to-HDL ratio values were significantly higher in steatohepatitis, whereas HDL was significantly lower compared with both fatty liver and controls. Free fatty acids were similar in all groups. Conclusions: Along with insulin resistance, serum LDL, and cholesterol-to-HDL ratio values increase with worsening severity of liver histology, and serum HDL values decline. Free fatty acids, however, do not vary between groups.