When patients first hear about ALAT and ASAT tests, the question often arises: what are they, and why are they important? Often, these indicators help detect serious liver diseases before symptoms appear. Elevated liver enzymes are a signal that further examination is needed. Sometimes the reason is simple and easily resolved (e.g., changing medication or improving lifestyle), but other times it can be the first warning sign of a more serious illness. Therefore, it is important to work with your doctor and undergo recommended examinations.
What are ALAT and ASAT?
ALAT (alanine aminotransferase) and ASAT (aspartate aminotransferase) are enzymes found in liver cells. When the liver is damaged—due to viral hepatitis, fatty liver disease (steatosis), or the influence of medications—these enzymes enter the bloodstream, and their levels rise. ALAT is a more specific marker of liver damage, while ASAT can also rise in cases of heart or muscle damage.
Why are liver tests important?
These tests are part of a basic liver examination. They help a general practitioner or gastroenterologist assess liver function and notice changes in time. For example, in my practice, a 45-year-old patient without symptoms was found to have an elevated ALAT level. After further examinations, including an abdominal ultrasound, fatty liver disease was diagnosed, which, when treated in time, prevented more serious complications.
Common reasons why enzymes may be elevated:
- Fatty liver (often associated with excess weight, diabetes, or high cholesterol).
- Alcohol consumption.
- Viral hepatitis (B or C).
- Side effects of medications or dietary supplements.
- Excessive iron accumulation in the body.
- Liver inflammation caused by the immune system.
- Muscle damage or changes caused by very intense physical exertion.
How to interpret ALAT and ASAT results?
Normal values can vary slightly depending on the laboratory, but generally, ALAT and ASAT levels should not exceed 40 U/L. If the indicators are elevated, the doctor evaluates their ratio, other test results, and the clinical picture. Elevated ALAT is more likely to indicate liver damage, while elevated ASAT may suggest potential muscle or heart issues. If both indicators are high, a detailed liver examination is performed, including an abdominal ultrasound.
Dr. Ruslans Mihailovskis
When should you have an abdominal ultrasound?
An abdominal ultrasound is a non-invasive method that allows for a visual assessment of liver structure. It is usually prescribed if ALAT or ASAT are elevated, or if there is a suspicion of fatty liver, cirrhosis, or a tumor. This examination is recommended for patients with vague symptoms—fatigue, a feeling of heaviness in the right upper quadrant, or jaundice.
Dr. Vladimirs Šalajevs
Frequently asked questions
Elevated liver enzymes are a signal that further investigation is required. While sometimes the cause is minor, it can also be the first indicator of a serious condition.
To get accurate results, the blood test must be done on an empty stomach. It is recommended to avoid alcohol, heavy food, and intense physical activity the day before. This is important because these factors can affect enzyme levels in the blood and lead to misleading results.
