Schilling's test

Its positivity confirms a resorption disorder of vitamin B12, (Addison-Bierner disease), when the level of this vitamin in the blood is typically reduced.

Procedure: Vitamín B12 administered to them saturates the receptors in the tissues, then radionuclide-labeled vit.B12 p.m.
 * If absorption is intact, the radioactive vitamin is absorbed and excreted in the urine.
 * In the case of malabsorption the vitamin leaves the body with the stool and less than 10% of the administered substance enters the urine.