The schilling test cannot be replaced by an absorption test with unlabeled vitamin B12

Abstract

It was the purpose of this study to evaluate the diagnostic usefulness of an oral absorption test using nonlabeled Vit B12 suggested by a commercial distributor as an alternative for the more expensive Schilling test (ST). Plasma levels of Vit B12 were measured with a commercial kit before and 4 h after oral administration of 1 mg Vit B12 in 32 normals, in 16 patients with normal ST, and in 14 patients with abnormal ST for determination of sensitivity and specificity with the ST as golden standard. In normals, a mean of 767 +/- 404 pg/ml before and 1096 +/- 776 pg/ml after oral Vit B12 with a mean increase of 331 +/- 453 pg/ml was measured. Because of the obvious large variation, no meaningful range for normal absorption could be established. In the two patient subsets, there was no Gaussian distribution of the results, with a meridian of Vit B12 increase after absorption of 142 pg/ml, range 27-2668 pg/ml, in the group with normal ST and a meridian of 244 pg/ml ranging from 40 to 2453 pg/ml in the group with abnormal ST. Statistical nonparametric analysis did not reveal any difference between the two groups. Assuming a minimum required increase of 100 pg/ml, as suggested by the kit distributor, a sensitivity of only 27% and a specificity of 75% was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Holo-Transcobalamin Concentration and Transcobalamin Saturation Reflect Recent Vitamin B12 Absorption Better than Does Serum Vitamin B12

“…Most previous studies have used a relatively larger single oral dose of vitamin B 12 (1000 g) (7,8 ). The crucial point here is that with this large dose of vitamin B 12 , the non-IF-mediated absorption of 1% alone will increase the plasma concentration, thereby giving false results.…”

“…To date such studies have not been unequivocal, most likely because the test used has been serum vitamin B 12 (7,8,14 ). Vitamin B 12 includes vitamin B 12 bound to two binding proteins.…”

Nonradioactive Vitamin B12 Absorption Test Evaluated in Controls and in Patients with Inherited Malabsorption of Vitamin B12

“…Evaluation of the intestinal absorption of vitamin B 12 is a necessary step in determining the etiology of vitamin B 12 deficiencies. All available tests, including the classic Schilling test, rely on measurement of radioactively labeled vitamin B 12 after an oral dose of the vitamin (1 ).…”

“…All available tests, including the classic Schilling test, rely on measurement of radioactively labeled vitamin B 12 after an oral dose of the vitamin (1 ). The use of a radioactively labeled compound has made the tests increasingly unacceptable (2 ).…”

“…The use of a radioactively labeled compound has made the tests increasingly unacceptable (2 ). An alternative approach is therefore needed for estimation of the absorption of vitamin B 12 . Measurement of vitamin B 12 -saturated transcobalamin (holo-TC) 4 or total cobalamin after oral ingestion of vitamin B 12 may represent such a test.…”