DefinitionThe Schilling test is used to determine whether the body absorbs vitamin B12normally.Alternative NamesVitamin B12 absorption testHow the test is performedThis test may be performed in four different stages to find the cause of low vitamin B12 levels.Stage I: You will get two doses of vitamin B12 (cobalamin). You will take a small, first dose (a radioactive form of B12) by mouth. You will a second, larger dose by a shot 1 hour later. You will need to collect your urine over the next 24 hours, and deliver it to a lab or your doctor's office. The urine will be checked to see if you are absorbing vitamin B12 normally. For information on collecting the urine sample, see: 24-hour urine collectionIf Stage I is abnormal, Stage II may be done 3 - 7 days later.Stage II: You are given radio