Blood test results can be confusing, especially when levels fall outside the normal range. Aspartate aminotransferase (AST) is a commonly tested enzyme. While high levels often draw attention, a low AST reading can also raise questions. This article explains what a low AST level might signify.
Understanding AST Levels
Aspartate aminotransferase (AST), also known as serum glutamic-oxaloacetic transaminase (SGOT), is an enzyme found in various body tissues, including the liver, heart, skeletal muscles, and kidneys. It is most commonly associated with liver health. Its primary role involves metabolizing amino acids, the building blocks of proteins.
A low AST level means the enzyme’s concentration in your blood is below the established normal reference range for adults. Normal ranges for AST are typically 8 to 40 units per liter (U/L), though these values can vary between laboratories and depend on factors like age, sex, and weight. While high AST levels often suggest organ damage or inflammation, particularly in the liver, low AST levels usually do not indicate severe underlying pathology.
Potential Reasons for Low AST
A lower-than-normal AST reading is often not a cause for alarm and may simply reflect normal biological variations. However, several specific factors and conditions can contribute to reduced AST levels.
One recognized reason for low AST is a deficiency in vitamin B6 (pyridoxine). Vitamin B6 is a cofactor necessary for AST to function correctly. Without adequate B6, the enzyme’s activity can be impaired, leading to lower measurable levels. This deficiency can stem from poor dietary intake, certain medications, or malabsorption disorders.
Chronic kidney disease (CKD) is another condition that can result in lower AST levels. Individuals with CKD, especially those undergoing hemodialysis, often exhibit reduced AST and ALT levels. This reduction may be due to factors like pyridoxine deficiency, hemodilution, or uremic factors that inhibit enzyme activity. Severe malnutrition can also contribute to low AST, potentially due to reduced muscle mass and impaired enzyme production. While some forms of malnutrition can increase liver enzyme levels, severe or chronic malnutrition may lead to lower AST due to factors like impaired lipid degradation or reduced muscle mass.
Pregnancy can influence AST levels, with some individuals experiencing slightly lower readings. Mild fluctuations are common during normal pregnancy. Certain medications, such as some statins or antibiotics like metronidazole, and even vigorous exercise, are also potential contributors to lower AST readings.
When to Consult a Healthcare Professional
An isolated low AST level, especially without other symptoms or abnormal test results, is not considered clinically significant. It rarely points to a serious health issue and does not require specific treatment. The most important step is to discuss your results with your healthcare provider.
Your doctor can interpret your AST levels within the context of your complete medical history, other laboratory findings, and any symptoms you might be experiencing. They will consider factors such as your age, sex, diet, and any medications you are currently taking, as these can all influence AST levels. Depending on the overall clinical picture, your doctor might recommend retesting your AST levels, investigating for potential vitamin B6 deficiency, or reviewing your current medication regimen. Self-diagnosis or attempting self-treatment based solely on a low AST reading is not advisable, as a healthcare professional provides accurate assessment and appropriate guidance.