Alanine aminotransferase (ALT) is an enzyme that plays a role in the body’s metabolic processes, particularly in converting food into energy. This enzyme is mainly found in the liver, but smaller amounts are also present in the kidneys, heart, and muscle cells. While elevated ALT levels often indicate liver damage, lower-than-normal levels can also be a subject of medical inquiry.
Understanding ALT and Low Levels
ALT, also known as serum glutamic-pyruvic transaminase (SGPT), is primarily concentrated in the liver. It plays a role in energy production. ALT also requires vitamin B6 to function properly.
Normal ALT levels can vary, but a commonly referenced range is between 7 and 56 units per liter (U/L) of blood. A level below this range is considered low. Generally, low ALT levels are not a cause for concern and are often considered benign.
Symptoms Potentially Linked to Low ALT
Low ALT levels typically do not cause specific symptoms, as the symptoms usually stem from the underlying condition responsible for the reduced ALT. If symptoms do appear, they can include persistent fatigue and weakness, numbness in the hands, arms, or legs, nausea, and difficulty concentrating. These general symptoms can be indicative of various health issues, not solely low ALT.
For example, some studies have linked extremely low ALT levels in the elderly with a higher risk of mortality from all causes, including heart disease and cancer. However, this association does not imply that low ALT is directly causing these conditions, but rather that it might be a marker of an underlying issue.
Common Causes of Low ALT Levels
One common reason is a vitamin B6 deficiency. This deficiency is more prevalent in older adults and individuals with existing liver or kidney damage. Chronic kidney disease can also contribute to low ALT. Other non-pathological factors that may be associated with reduced ALT levels include aging, extreme physical activity, smoking, and the use of certain medications like birth control pills or hormone therapy. In rare cases, severe liver disease or malnutrition may also be linked to decreased ALT levels.
When to Seek Medical Advice
While a low ALT result is often not a concern, it is advisable to consult a healthcare professional if persistent low levels are accompanied by other symptoms. These symptoms might include ongoing fatigue, unexplained weight loss, or muscle weakness. A doctor can evaluate your overall health, consider other blood test results, and determine if further investigation is necessary.
An isolated low ALT reading without other concerning symptoms or abnormal test results is usually considered normal and benign. However, if you have any questions about your specific ALT results or are experiencing new or concerning symptoms, seeking medical advice is a prudent step.