Methylmalonic Acid (MMA) Test

The Methylmalonic Acid (MMA) test is a medical diagnostic tool used to assess the levels of methylmalonic acid in the blood or urine. This test is primarily utilized to diagnose and monitor vitamin B12 deficiency, as well as certain disorders related to the metabolism of branched-chain amino acids and odd-chain fatty acids.

Purpose

The main purpose of the MMA test is to:

• Detect vitamin B12 deficiency or insufficiency, as methylmalonic acid levels are elevated in the absence of sufficient vitamin B12.
• Diagnose and monitor disorders related to the metabolism of branched-chain amino acids and odd-chain fatty acids, such as methylmalonic acidemia.
• Evaluate the effectiveness of vitamin B12 supplementation or other treatments aimed at reducing MMA levels.

Procedure

The MMA test typically involves collecting a blood or urine sample from the patient. The procedure may vary depending on the laboratory and the specific requirements of the test, but generally includes:

• Blood collection: A healthcare professional will draw a blood sample from a vein in the arm using a needle and syringe.
• Urine collection: A urine sample may be collected over a 24-hour period or as a random sample, depending on the laboratory's requirements.

Interpretation of Results

The results of the MMA test are typically interpreted in conjunction with other diagnostic tests and clinical evaluations. Elevated levels of methylmalonic acid may indicate:

• Vitamin B12 deficiency or insufficiency.
• Methylmalonic acidemia, a rare genetic disorder affecting the metabolism of certain amino acids and fatty acids.
• Other disorders related to the metabolism of branched-chain amino acids and odd-chain fatty acids.

Reference Ranges

The reference ranges for MMA levels may vary depending on the laboratory, age, and other factors. Generally, the following reference ranges are used:

• Blood: Less than 0.4 μmol/L (micrograms per liter) is considered normal.
• Urine: Less than 3.6 μmol/mmol creatinine is considered normal.

Clinical Significance

The MMA test has significant clinical implications, as elevated levels of methylmalonic acid can indicate underlying disorders that require prompt medical attention and treatment. Vitamin B12 deficiency, for example, can cause a range of symptoms, including fatigue, weakness, and neurological problems, if left untreated.