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What is The Schilling test is used for detecting: and explain in detail?
SCHILLING TEST (24-HOUR URINARY EXCRETION TEST): 

Schilling test is done to detect vitamin B12 deficiency as well as to distinguish and detect lack of intrinsic factor and malabsorption syndrome. 
The results of test also depend upon good renal function and proper urinary collection.
Radioisotope used for labeling B12 is either 58Co or 57Co.

​Mohan H. Textbook of pathology. Jaypee Brothers Medical Publishers; 2015. Edition 7. Page 284