According to a recent report (Hepatology 2015; 61: 153-60), elevation of alanine aminotransferase (ALT) which is frequently used as an indicator to select patients for further investigations (eg. liver biopsy) is NOT a good indicator of liver parenchymal injury in patients with nonalcoholic fatty liver disease (NAFLD).
The researchers enrolled 440 patients and divided them into three groups: no NAFLD (n=60), NALFLD with normal ALT (n=165), and NAFLD with elevated ALT (n=215). The patients were overweight/obese patients prospectively recruited from newspaper ads, general medicine clinics and hepatology clinics at several VA hospitals. Those with history of alcohol abuse were excluded.
Numerous investigations were performed including liver fat by proton magnetic resonance spectroscopy (H-MRS), liver biopsy (n=293), and insulin resistance measurements.
- NAFLD & NASH patients with elevated ALT had higher liver triglyceride content (P<0.0001), worse adipose tissue insulin resistance (ATIR) (P<0.0001), and lower plasma adiponectin (P<0.05).
- Steatosis was worse on liver biopsy in those with NASH and elevated ALT (P<0.0001).
- There were no differences in liver inflammation (P=0.62), ballooning (P=0.13), or fibrosis (P=0.12). Thus, patients with normal versus elevated ALT had similar severity of NASH liver histology.
Take-home message: In adults, ALT values are “poor surrogate markers of disease activity” in NAFLD. ALT values, in these patients, are indicative of metabolic disease. Given the staggering numbers of individuals, adults and children, with fatty liver disease, the lack of simple screen tool is quite problematic. Equally problematic is a lack of a simple treatment approach.
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