Tests for diagnosing and monitoring non-alcoholic fatty liver disease in adults

At a routine health check arranged by his company, a 52 year-old sedentary male computer programmer was found to have a serum alanine aminotransferase (ALT) concentration of 68 IU/L (normal 0-40 IU/L), and a triglyceride concentration of 1.9 mmol/L.His fasting plasma glucose levels were 5.8 mmol/L and other basic liver, renal and lipid blood tests were normal.He had an unremarkable medical history and took no regular medications, did not smoke and consumed <7 units of alcohol/week.Clinical examination was unremarkable.His body mass index was 29 kg/m 2 ; waist circumference 102 cm and blood pressure 134/88 mmHg. What is the next investigation?His general practitioner requested a liver ultrasonography (confirming the presence of hepatic steatosis) and a repeat serum ALT measurement was 62 IU/L.Other blood tests (including serology for hepatitis B and C viruses, liver auto-antibodies and ferritin) excluded other causes of liver dysfunction.The patient is likely to have non-alcoholic fatty liver disease (NAFLD).Box 1 describes how patients with NAFLD usually present.When LFTs (e.g.serum aminotransferases such as serum ALT levels) are increased (above the laboratory recommendation for the upper limit of normal), patients should be further investigated to diagnose (or exclude) NAFLD.Figure 1 illustrates a potential investigative pathway for diagnosing NAFLD and for identifying other common causes of chronic liver disease.When patients have any of the common cardiometabolic risk factors shown in Box 2 plus abnormal LFTs, it is likely the diagnosis is NAFLD (in the absence of other risk factors for liver disease shown in Box 3).