It is important, however, to detect and treat vitamin B-12 deficiency in the early stages before significant damage occurs.
Untreated deficiency may lead to neurologic damage and an increased risk of birth defect–affected pregnancies even when the deficiency is only moderate (8-11).
Once in circulation, holo-TC is taken up into cells within minutes (2, 3).
Depletion of total body cobalamin occurs slowly and is often a result of malabsorption, which is difficult to diagnose clinically (4-7).
In developing a clinical diagnostic test, it is important to know the optimal time after the dose at which to draw blood.
A total of 17 timed blood draws were taken from day 1 to day 3, and three 9-μg doses of vitamin B-12 were administered at 6-h intervals on day 1, beginning after the baseline blood draw (Figure 1).
Immediately after taking each vitamin B-12 dose, subjects consumed a piece of bread and 236 m L (8 oz) juice to improve absorption efficiency (20).
Pernicious anemia, the specific vitamin B-12 deficiency condition caused by a lack of intrinsic factor (IF), may result from an autoimmune response to IF or gastric parietal cells, atrophy of the gastric mucosa, chronic gastritis, and, in rare cases, a congenital defect.
Currently, the only available diagnostic tests for pernicious anemia are not clinically practical.