Analysis index

1 ml serum
10 ml urine

Serum: < 32 µg/l

Urine: < 4 mg/g Crea

Vitamin B12 deficiency, hereditary methylmalonic aciduria

Methylmalonic acid, same as homocysteine, is an indirect parameter of the vitamin B12 supply. It originates from the B12-dependent conversion of methylmalonyl-CoA into succinyl-CoA in the context of the degradation of odd-numbered fatty acids as well as the amino acids methionine, valine, and isoleucine. A cobalamin deficiency leads to an accumulation of methylmalonyl-CoA, which hydrolyses non-enzymatically into methylmalonic acids and CoA. An increase in methylmalonic acid in the blood or in the urine therefore points to a deficiency, even if the vitamin B12 levels in the blood are inconspicuous. Methylmalonic acid values increased by a two-fold can revert to the normal range already 7 days after supplementation with vitamin B6, B12 and folic acid. Please be aware, that in case of a decreased glomerular filtration rate and independent of a vitamin B12 deficiency, the concentration in the blood is increased. In this case, the therapeutic decrease of methylmalonic acid concentration in the serum by administering cobalamin will support a deficiency. Severely increased serum and urine concentrations in children are an indication of a hereditary methylmalonic aciduria with defects in the methylmalonyl-CoA mutase or in the development of adenosylcobalamin.

Please also refer to:      Organic acids