[Diagnosis of vitamin B12 deficiency--time for reflection].
Since plasma methylmalonic acid (MMA) was introduced in Denmark in 1992 both MMA and P-cobalamins have been increasingly employed to diagnose vitamin B-12 deficiency, and the consumption of vitamin B-12 has been almost doubled during the same period. The controversy about diagnosing vitamin B-12 deficiency is reflected in a huge geographical variation both in requisition of MMA and P-cobalamins and in the vitamin B-12 consumption. On the basis of studies performed so far we conclude that MMA is a reliable method with a good nosographic sensitivity. However, the nosographic specificity is sparsely examined, and the evidence to use MMA as a primary test for diagnosing vitamin B-12 deficiency is still insufficient. We recommend P-cobalamins as the first line test, and if P-cobalamins are in the grey area 125-250 pmol/l we recommend supplementation with MMA. For patients who also have an MMA in the grey area (0.29-0.75 mumol/l) we recommend that the patient is re-examined after about a year.
Hvas
Anne-Mette
AM
Klinisk Biokemisk Afdeling, Arhus Kommunehospital, DK-8000 Arhus C. am.hvas@dadlnet.dk
Ellegaard
Jørgen
J
Nexø
Ebba
E
D015415:Biomarkers / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008764:Methylmalonic Acid / Q000097:blood; D012680:Sensitivity and Specificity; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy
D015415:Biomarkers; D006710:Homocysteine; D008764:Methylmalonic Acid; D014805:Vitamin B 12