The Schilling test detects the ability of your body to digest and utilize vitamin B-12 normally and determines if you have pernicious anemia. The test has four stages, but all stages may not be necessary for a diagnosis. Vitamin B-12, also called cobalamin, is derived from protein food sources. It is essential for production of red blood cells and helps maintain the nervous system. Vitamin B-12 deficiency can cause a severe anemia called pernicious anemia.
Pernicious Anemia
Pernicious anemia can be inherited, the result of a vitamin B-12 deficiency or an inability to absorb B-12 in the small intestine. B-12 absorption requires a protein called intrinsic factor, which is produced by cells lining the stomach. Intrinsic factor and B-12 bind together and absorption occurs in the small intestine. Inherited pernicious anemia requires that both parents carry the gene and anemia is present at birth. Vegetarians can develop pernicious anemia resulting from a lack of protein in their diets.
Test Stages
Stage 1 of the test requires two doses of radioactive cobalamin. The first dose is oral with a larger dose injected one hour later. Urine, collected over 24 hours, is evaluated for B-12 absorption. Stage 2 follows 3 to 7 days later with doses of radioactive cobalamin and intrinsic factor to detect stomach disorders. Stage 3 is two weeks of antibiotic therapy to detect abnormal intestinal bacterial growth. Stage 4 consists of more radioactive cobalamin given after three days of pancreatic enzymes to detect pancreatic problems.
Preparation
Test preparation requires fasting for eight hours before the test, with water allowed, and then eating normally for 24 hours. Notify your physician of all prescribed and over-the-counter medications you've been taking as some medications might interfere with the test. B-12 injections alter test results so withholding injections is required for three days prior to the test. With the test, you might experience nausea, dizziness and a stinging sensation at the site of the injection.
Results and Treatments
If stage 1 is abnormal but stage 2 is normal, it indicates the stomach is unable to produce intrinsic factor. If stage 1 and 2 are abnormal, then absorption in the small intestine of B-12 and intrinsic factor is the primary problem. Treatment includes vitamin B-12 injections, B-12 pills, vitamin supplements and increased protein sources in the diet including meat, shellfish, poultry, dairy products and eggs. Vegetarians might require long term B-12 injections because their diets lacks these sources of protein.
Considerations
Red blood cells are formed in the bone marrow and normally cross into the bloodstream without difficulty. With vitamin B-12 deficiency, the red blood cells formed are much larger in size and passage out of the marrow and into the bloodstream is impeded. The reduction of circulating red blood cells and decrease in oxygen-rich blood leads to symptoms of weakness and fatigue. Acute and chronic pernicious anemia can harm vital organs including the heart and brain.
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