Synonyms: B12
Related tests: Folic acid, Homocysteine, full blood count
Clinical significanceSample typePreparation
Clinical significance
Vitamin B12 enters the body through food but is absorbed only after binding to a glycoprotein produced by the cells of the stomach lining (called intrinsic factor; when it is lacking because of atrophy of the stomach lining, the vitamin is not absorbed, leading to macrocytic anaemia).
Vitamin B12 is involved in the synthesis of purines (DNA) and fatty acids (myelin) and in methionine metabolism
Sample type
The patient must have a blood sample taken.
Preparation
You must fast for at least 8 hours; a small amount of water is allowed. You must have been standing or sitting upright for at least 30 minutes.