Elevated liver enzymes and fatty liver
After all other potential causes have been ruled out, I attribute elevated liver enzymes (aspartate aminotransferase and alanine aminotransferase) to a fatty liver. This, of course, is usually noted on ultrasound or CT scan. How often should the enzymes be checked as part of routine monitoring? When should additional tests be ordered if the enzyme levels continue to rise?
—Ashley Snellen, MSN, FNP, Mt. Washington, Ky.
The American Gastroenterological Association has published a medical position statement regarding nonalcoholic fatty liver disease (NAFLD) (Gastroenterology. 2002;123:1702-1704). When elevated liver enzymes are identified, alcohol use should be assessed and, if a factor, discontinued. Common causes of elevated enzymes (e.g., infectious hepatitis, hemochromatosis, Wilson disease, celiac disease, autoimmune hepatitis, primary biliary cirrhosis, alpha1-antitrypsin deficiency, and medication/herbal toxicity) should be ruled out by appropriate testing and history.
Ultrasound should be performed to identify fatty liver, but the only way to make an accurate diagnosis is with a biopsy. The necessity for and timing of liver biopsy has been highly controversial. Traditionally, those who have mild liver enzyme elevations in the absence of alcohol and in whom other causes have been ruled out are instructed to lose weight through diet and exercise and to control other risk factors for NAFLD (i.e., hyperlipidemia, hypothyroidism, and diabetes). Six-month follow-up with an office visit and liver enzyme determination has been the norm. If the enzymes have not improved, liver biopsy has historically been recommended to obtain a definitive diagnosis and determine if fibrosis is present. This practice has been called into question, since the majority of biopsies have yielded fatty liver and management has not been changed as a result of the biopsy. If the enzymes are stable, the recommendation is to check them every six months. However, if they rise dramatically or continue to rise gradually, a liver biopsy should be considered, since NAFLD can lead to nonalcoholic steatohepatitis and cirrhosis.
—Bruce D. Askey, MSN, CRNP (123-12)