Vit b12 Schilling 130316051450 Phpapp01 [PDF]

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Schilling test Dr.CSBR.Prasad, M.D.,

FIGURE 14-18 Schematic illustration of vitamin B12 absorption. IF, intrinsic factor; R-binders, cobalophilins

Schilling test Investigation used for patients with vitamin B12 deficiency • The purpose of the test is to determine whether the patient has pernicious anemia • The Schilling test has multiple stages

Stage 1: oral vitamin B12 plus intramuscular vitamin B12 • Oral dose: patient is given radiolabeled Vit B12

– The most commonly used radiolabels are 57Co and 58Co

• An intramuscular injection of unlabeled vitamin B12 is given an hour later • The patient's urine is then collected over the next 24 hours to assess the absorption • A normal result shows at least 10% of the radiolabeled vitamin B12 in the urine over the first 24 hours • In patients with impaired absorption, less than 10% of the radiolabeled vitamin B12 is detected

Stage 2: Vitamin B12 + IF If an Stage-I is abnormal: The test is repeated with additional oral intrinsic factor • If this second urine collection is normal, this shows a lack of intrinsic factor production, or pernicious anemia. • A low result on the second test implies “Malabsorption” – – – – – – –

Coeliac disease Biliary disease Whipple's disease Fish tapeworm infestation (Diphyllobothrium latum), or Liver disease Immerslund syndrome Malabsorption of B12 can be caused by intestinal dysfunction from a low vitamin level in-and-of-itself

Stage 3: vitamin B12 and antibiotics • This stage is useful for identifying patients with bacterial overgrowth syndrome.

Stage 4: vitamin B12 and pancreatic enzymes • This stage, in which pancreatic enzymes are administered, can be useful in identifying patients with pancreatitis.

Combined stage 1 and stage 2 • In some versions of the Schilling's test, B12 can be given both with and without intrinsic factor at the same time, using different cobalt radioisotopes 57Co and 58Co, which have different radiation signatures, in order to differentiate the two forms of B12. • This allows for only a single radioactive urine collection

DDs for Microcytic Hypochromic Anemia

DD for microcytic hypochromicanemia Diagnosis of Microcytic Anemia Tests

Iron Deficiency Inflammation Thalassemia

Smear

Micro/hypo

Normal micro/hypo

Micro/hypo Variable with targeting

SI