A 45 year old man with known hypertension, type 2 diabetes mellitus, and central obesity presents with fatigue and mild discomfort in the abdominal right upper quadrant. Repeated blood tests show a persistent alanine aminotransferase concentration of 100 IU/l (reference range 10-50) and a γ glutamyl transferase concentration of 80 IU/l (range 10-50) with serum bilirubin and other liver test results in the normal range. He drinks two glasses of wine a month and denies any history of excessive alcohol consumption. Tests (including negative serology for hepatitis B and C viruses) exclude other causes of liver dysfunction. You explain that he is likely to have non-alcoholic fatty liver disease. Non-alcoholic fatty liver disease, the hepatic manifestation of the metabolic syndrome, occurs predominantly in patients with central obesity, hypertension, abnormal glucose tolerance, and dyslipidaemia. It is now the most common cause of abnormal liver function test results, with a prevalence approaching 30% in unselected patients throughout the world. Fatigue and abdominal pain are sometimes reported but are uncommon. Most patients are asymptomatic and come to attention only because of incidental findings on liver tests or hepatic ultrasound (which you should ask for if you suspect non-alcoholic fatty liver disease). As well as the metabolic syndrome, other disorders can predispose patients to the disease, such as …