Methylmalonic Acid, Urine Unit Converter

Urine methylmalonic acid (MMA) is a metabolic byproduct that accumulates when vitamin B12 (cobalamin) levels are insufficient. MMA is produced during the breakdown of certain amino acids and fatty acids, and vitamin B12 is required to convert it into another compound called succinyl-CoA.

When B12 is deficient, this conversion cannot occur properly, causing MMA to build up in the blood and spill into the urine. Measuring urine MMA provides a sensitive and specific way to detect early or mild vitamin B12 deficiency, often before blood B12 levels decline or symptoms appear.

Urine MMA testing is also used to monitor methylmalonic acidemia, a rare inherited metabolic disorder that causes MMA to accumulate regardless of B12 status.

MMA is produced throughout the body during normal protein and fat metabolism. It originates from the breakdown of amino acids (valine, isoleucine, methionine, and threonine), odd-chain fatty acids, and cholesterol side chains. A portion also comes from bacterial fermentation in the gut.