Background and aims Prolonged elevation of the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) is as biochemical indicators for hepatic diseases. However, these enzymes are also present in a variety of extrahepatic tissues, including skeletal muscle. The aim of this study was to call the attention to the often disregarded message that high level of transaminases may be a marker of both liver and muscle diseases.

Methods We report a case series that included three male patients who were admitted to our paediatrics unit during the last 24 months with persistent elevated serum levels of aminotransferases. The diagnostic work-up included physical examination, screening for liver disease and muscular dystrophy: serum level of transaminases, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH).

Results The patients, all boys, were aged between 3 and 5 years, mean age of 3.7 years. The initial ALT and AST values were between 486–890 U/L and 344 and 680 U/L respectively. The serum level of ALT, generally considered to be specific for hepatocellular injury, was increased 10 to 25 times above normal in all the reported cases. LDH serum level was increased for all patients The neurological findings were all not remarkable: difficulty in running and jumping, frequent falls. Serum CPK level was found significantly increased. Genetic studies showed deletions in the Duchenne muscle dystrophy gene, exons 45–48 and 48-49-50 respectively. Paradoxically, the increase in ALT activity was greater than that of serum AST level.

Conclusions High level of transaminases is most striking during the early stage of muscular dystrophy, before onset of or when only subtle signs of muscle disease are present. Serum CPK level and careful physical examination are the most useful and cost-effective means of correctly identifying these patients.