From the Guidelines
Isolated elevated Aspartate Aminotransferase (AST) typically does not require hospital admission in most cases. The decision to admit should be based on the patient's overall clinical presentation, the degree of elevation, and the presence of symptoms rather than the AST level alone, as suggested by the American Gastroenterological Association medical position statement 1. Mild to moderate AST elevations (less than 5-10 times the upper limit of normal) without symptoms can generally be managed in an outpatient setting with appropriate follow-up within 1-2 weeks. However, hospital admission should be considered if the AST elevation is severe (greater than 10-20 times normal), rapidly rising, accompanied by significant symptoms (severe abdominal pain, jaundice, encephalopathy), or if the patient has signs of acute liver failure, hemodynamic instability, or coagulopathy.
The initial outpatient workup should include:
- A complete metabolic panel
- Complete blood count
- Coagulation studies
- Additional liver tests including ALT, alkaline phosphatase, bilirubin, and albumin, as outlined in the guidelines for evaluating patients with evidence of hyperbilirubinemia and cholestasis 1. AST elevations often reflect liver injury but can also originate from muscle, heart, or other tissues, so the clinical context is crucial for interpretation. Patients should be advised to avoid hepatotoxic substances including alcohol and certain medications while the cause is being investigated. The guidelines serve to provide a rational approach for the interpretation and evaluation of abnormal serum liver chemistries, emphasizing the importance of considering the clinical scenario specific to an individual patient 1.
From the Research
Isolated Elevated AST (Transaminitis) and Hospital Admission
- Isolated elevated Aspartate Aminotransferase (AST) does not necessarily require hospital admission, as it can be caused by a benign condition known as macro-AST 2, 3, 4, 5.
- Macro-AST is a rare condition where the AST enzyme forms a high-molecular mass complex that is difficult for the kidney to clear, leading to isolated elevation of serum AST activity 4.
- The presence of macro-AST can be confirmed by polyethylene glycol (PEG) precipitation tests 2, 3, 4, 5.
- In asymptomatic patients with isolated elevated AST, macro-AST should be considered as a cause of the elevation to avoid unnecessary investigation and patient anxiety 2, 4, 5.
- Studies have shown that patients with isolated elevated AST due to macro-AST do not develop significant liver disease and have a benign course 6.
- The diagnosis of macro-AST can be established by PEG precipitation, which is a feasible and cost-effective way to avoid costly and potentially harmful medical tests or procedures 5.