Understanding ALT on a Blood Test
Alanine aminotransferase, commonly known as ALT, is an enzyme primarily found within liver cells. While low levels of ALT are normally present in the bloodstream, its measurement in a blood test serves as a valuable indicator of liver health. When liver cells experience irritation or damage, they release excess ALT into the blood, leading to elevated levels that signal a potential liver issue.
Understanding Your ALT Levels
A general reference for a normal ALT range typically falls between 7 to 56 units per liter (U/L), though specific laboratory ranges can vary slightly. Always consult the reference values provided by the laboratory that performed your test. Some experts suggest optimal ALT levels might be lower, around 30 U/L for men and 25 U/L for women, particularly for those prioritizing preventive health.
The degree of elevation can offer clues; for instance, levels exceeding 1000 U/L might point to acute conditions like severe drug-induced liver injury or acute viral hepatitis. Conversely, very low ALT levels are uncommon and typically do not raise significant clinical concerns, though they could rarely indicate a vitamin B6 deficiency or chronic kidney disease.
Factors Affecting ALT Levels
Several conditions and lifestyle choices can lead to elevated ALT concentrations.
Liver-Related Causes
Liver diseases are common culprits, including non-alcoholic fatty liver disease (NAFLD), often linked to obesity and diabetes. Viral hepatitis (types A, B, or C) can cause substantial ALT increases, with acute infections potentially raising levels 20 to 50 times above normal. Autoimmune hepatitis, where the body’s immune system attacks liver cells, and cirrhosis, which involves severe liver scarring, also contribute to higher ALT.
Medications and supplements can induce liver injury, leading to elevated ALT. This includes certain over-the-counter pain relievers like acetaminophen, cholesterol-lowering drugs, and various prescription medications. Alcohol consumption is another significant factor, as alcohol breakdown negatively impacts liver health and can elevate ALT.
Other Causes
Beyond liver-specific issues, other bodily conditions can influence ALT. Strenuous physical activity, such as intense weightlifting or endurance exercise, can temporarily increase ALT levels due to muscle damage. Conditions like mononucleosis, caused by the Epstein-Barr virus, can also lead to elevated liver enzymes, typically two to five times the normal range. Celiac disease, an immune disorder triggered by gluten, is another known cause of mild to moderate ALT elevation, which often normalizes with a gluten-free diet.
Navigating Abnormal ALT Results
If a blood test reveals abnormal ALT levels, consulting a healthcare professional is the appropriate next step.
Next Steps After Abnormal Results
They will consider your medical history, symptoms, and other test results to determine the underlying cause. Further diagnostic evaluations might include additional liver function tests, such as aspartate aminotransferase (AST) and bilirubin, or imaging studies like an ultrasound of the liver. In some cases, a liver biopsy may be performed to assess the extent of liver damage.
Lifestyle and Management
Depending on the identified cause, lifestyle modifications may be recommended to help manage ALT levels. These often involve dietary changes, such as reducing saturated fats and refined carbohydrates, increasing fruit and vegetable intake, and possibly incorporating coffee. Limiting or avoiding alcohol consumption and engaging in regular physical activity are frequently advised. Maintaining a healthy weight can also support liver health and contribute to lowering ALT. Self-diagnosis or self-treatment based solely on ALT results is not advisable.