Aspartate aminotransferase (ASAT)

Elevated ASAT can act as an early warning sign of liver, heart, or muscle issues. Comparing ASAT with ALAT levels helps identify the likely source of organ damage - when both are elevated, liver issues are more likely, while isolated ASAT elevation may point to heart or muscle problems. Lifestyle factors such as alcohol intake, physical activity intensity, and overall health can influence ASAT levels. Monitoring ASAT provides insight into early tissue changes and can guide lifestyle adjustments to support liver, heart, and muscle health.

Most adults benefit from checking ASAT once a year as part of standard liver screening. When tracking a liver-focused intervention, retest at 3 to 6 months alongside ALAT and GGT.

At baseline / for screening: Once every 12 months from age 30 as part of a comprehensive panel. More frequently, every 3 to 6 months, if you have known liver disease, regular alcohol intake, fatty liver (MASLD), or take hepatotoxic medication.

When monitoring an intervention or change: Retest 3 to 6 months after a sustained lifestyle change for fatty liver, such as meaningful weight loss (5 to 10 percent of body weight), reducing alcohol, improving sleep, or shifting toward a Mediterranean-style diet. Retest 4 to 6 weeks after starting a hepatotoxic medication (statin, methotrexate, isoniazid, certain antifungals) to confirm tolerance. If a result was meaningfully elevated, your clinician guides the follow-up.

Note: ASAT rises with muscle damage as well as liver injury (intense exercise, injections, or major exertion can elevate it). Wait 5 to 7 days of normal activity before retesting if a result looks high in the absence of other liver signs.