A prospective study of the causes of notably raised aspartate aminotransferase of liver origin

Abstract

Background and aims: To ascertain the causes of raised aspartate aminotransferase (AST) presumed to be of hepatic origin in two hospitals and the local community served by a centralised biochemistry laboratory.

Methods: From June 1996 to February 1997 all patients with AST greater than 400 U/l were identified by the biochemistry laboratory; the patients' clinical records were studied to determine the diagnosis, the clinical outcome, and whether the raised AST and its significance had been noted.

Results: A total of 137 patients with a hepatic cause for the raised AST were found. The cause of the raised AST was hepatic ischaemia/hypoxia in 68, pancreatobiliary disease in 33, primary hepatocellular disease in 23, hepatic malignancy in five, and hepatic haematoma in one. In seven patients the diagnosis was unclear. The overall mortality was high (22%) with the highest mortality in the hepatic ischaemia group (37%). The recording and interpretation of the causes of raised AST was poor with only 48% having the correct diagnosis. In 38% the raised AST was apparently not noticed by the attending clinicians.

Conclusions: The commonest cause of a hepatitis like biochemical picture was hepatic hypoxia (50%) followed by pancreatobiliary disease (24%). Drug induced hepatic necrosis (8.8%) was uncommon and viral hepatitis was rare (3.6%). AST concentrations returned towards normal most rapidly in patients with hepatic hypoxia and calculous biliary obstruction. Hepatitis, viral or otherwise, is an uncommon cause of a typical hepatitic biochemical result in this community.

Figure 1

Causes of aspartate aminotransferase (AST) greater than 400 U/l.

Figure 2

Aetiology of hepatic ischaemia.

Figure 3

Subdivision of pancreatobiliary causes of aspartate aminotransferase (AST) greater than 400 U/l.

Figure 4

Hepatocellular causes of aspartate aminotransferase (AST) greater than 400 U/l.

Figure 5

Peak aspartate aminotransferase (AST) values for each final diagnosis (with medians); two points excluded: 27 575 (hepatocellular) and 10 393 (unknown).