› Screen patients with non-alcoholic fatty liver disease (NAFLD) for type 2 diabetes mellitus. A
› Treat components of the metabolic syndrome to improve the clinical outcome in patients with NAFLD. A
› Consider liver-directed pharmacotherapy, such as antioxidants (eg, vitamin E), insulin sensitizers, bile acid sequestrants, and pentoxifylline, to treat severe NAFLD. B
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
CASE › A 39-year-old Hispanic man with a body mass index (BMI) of 35 kg/m2, type 2 diabetes mellitus (T2DM), and hypertension is referred for evaluation of abnormal liver function tests (LFTs) and fatty liver on ultrasound. He is taking metformin and lisinopril, and a patient alcohol screening survey is negative. LFT results reveal the following: alanine aminotransferase (ALT) 27 IU/dL; aspartate aminotransferase (AST) 43 IU/dL; albumin 4.2 g/dL; gamma glutamyl transferase 22 u/L; alkaline phosphatase 51 IU/L; and total bilirubin 0.3 mg/dL. Lactate dehydrogenase and prothrombin time are normal.
Results of his liver screen are as follows: hepatitis B surface antigen, hepatitis C antibody, antimitochondrial antibody, and anti-smooth muscle antibody are negative, and iron, transferrin saturation, and ceruloplasmin are in normal range. Antinuclear antibody (1:20 dilution) is weakly positive, and alpha-1 antitrypsin (264 mg/dL) and serum ferritin (300 ng/mL) are mildly increased.
The patient undergoes a liver biopsy that shows grade 2 steatosis, grade 1 lobular inflammation, few ballooned hepatocytes, and stage 1 fibrosis. Based on these clinical findings, he is given a diagnosis of non-alcoholic fatty liver disease (NAFLD).
NAFLD is the most frequent cause of chronic liver disease both in the United States and globally.1 In fact, a number of long-term epidemiologic studies report that nearly one-third of the US population has the disease.2 The spectrum of NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis (NASH) to cirrhosis. Of patients with NAFLD, 10% to 30% have the more severe form—NASH—and about 10% of those with NASH progress to cirrhosis and other liver-related complications.3
People with NAFLD consume no alcohol, or only a modest amount (ie, weekly intake <140 g in women and <210 g in men). Typically, they are asymptomatic with normal or mildly abnormal LFTs discovered as part of a preventive health screening. In patients with simple hepatic steatosis alone, serum ALT levels are higher than serum AST levels. (In contrast, patients with alcoholic liver injury and NASH with progressive fibrosis have higher serum AST than ALT levels.) A serum hepatitis panel and liver screen are negative for other explanations of chronic liver disease.
NAFLD is strongly associated with obesity, insulin resistance/T2DM, and hyperlipidemia, all of which are components of metabolic syndrome. Obesity, particularly central obesity, is highly predictive of hepatic steatosis and disease progression.4 T2DM occurs 5 to 9 times more frequently in people with NAFLD than in the general population,5 and, conversely, nearly 66% of patients with T2DM have NAFLD.6,7 Furthermore, nearly 70% of patients with T2DM develop fatty liver and its consequences, including NASH, fibrosis, cirrhosis, and hepatocellular carcinoma.5,7
4 therapeutic strategies. Based on our current understanding of the pathogenesis of NAFLD, there are 4 main therapeutic avenues: lifestyle modification, liver-directed pharmacotherapy, management of metabolic syndrome, and surveillance of the complications of cirrhosis. The review that follows explores the evidence to date for each.
Take steps to reduce weight and increase physical activity
The primary objective with NAFLD is to right the imbalance between calorie intake and utilization so as to reverse the obesity and insulin resistance underlying the disease.
Target carbohydrates. Current data clearly suggest that energy intake is significantly higher in patients with NAFLD than in those without the disease.8 Thus, reducing dietary carbohydrate and overall energy intake is beneficial to preventing and halting the progression of liver damage. Increased intake of high fructose corn syrup may be at least partially to blame; research has linked the substance to the occurrence of obesity, metabolic syndrome, and NAFLD.9
The optimal diet to treat NAFLD is not known because of the difficulties inherent to performing well-designed dietary intervention trials and ensuring long-term compliance. At least one study reported that a Mediterranean diet helped reduce hepatic steatosis and improve insulin sensitivity in nondiabetic individuals.10 Generally, patients should avoid saturated fats, simple carbohydrates, and sweetened drinks, and they should be instructed to restrict calories to cause weight loss of about .5 kg to 1 kg per week until the target weight is achieved.11