From the Guidelines
Yes, aspartate transaminase (AST) can often be normal in cirrhosis, especially in advanced cases with fewer functioning hepatocytes. According to a 2019 consensus guideline on the detection, assessment, and management of suspected acute drug-induced liver injury during clinical trials in patients with nonalcoholic steatohepatitis 1, patients with advanced liver disease can have normal AST values or only mild elevations. This is because the AST:ALT ratio may increase to >1 in such patients, and the ratio may increase as the disease progresses. Key points to consider in the assessment of liver function in cirrhotic patients include:
- The AST:ALT ratio may be elevated in cirrhosis, even if AST levels are normal
- Patients with preexisting liver dysfunction may present with rapid deterioration of liver function, with only mild changes in AST levels
- Close monitoring is essential in such patients to enable early detection of the first signs of drug-induced liver injury (DILI) and ensure early discontinuation of the drug. In clinical practice, it is essential to interpret AST levels in the context of the patient's overall clinical presentation and other laboratory markers of liver function, rather than relying solely on AST levels to assess liver disease severity.
From the Research
AST Levels in Cirrhosis
- AST levels can be normal or near normal in patients with cirrhosis, as shown in a study of 78 patients with alcoholic cirrhosis, where 12 patients had a normal AST level 2.
- The average AST level in this study was 59 ± 34 U/L, which is slightly elevated, but still within the normal range for some patients.
- Another study found that the AST/ALT ratio was significantly higher in cirrhotic patients than in non-cirrhotic patients, suggesting that AST levels may be elevated in cirrhosis, but not always 3.
Prognostic Value of AST
- The AST/ALT ratio has been shown to have prognostic value in patients with viral liver cirrhosis, with a ratio of 1.17 or higher having 87% sensitivity and 52% specificity for predicting death after 1 year 4.
- However, another study found that an AST/ALT ratio of 1 or higher was not as useful for predicting cirrhosis in chronic hepatitis C as previously thought, with a positive predictive value of only 64% 5.
Clinical Implications
- Clinicians should be cautious when interpreting AST levels in patients with cirrhosis, as normal or near normal levels do not necessarily rule out cirrhosis 2.
- The AST/ALT ratio may be a useful indicator of cirrhosis in some patients, but its prognostic value is still uncertain and requires further study 4, 3, 5.