Reliability of the Dual-isotope Schilling Test for the Diagnosis of Pernicious Anemia or Malabsorption Syndrome

Abstract

To evaluate the dual-isotope Schilling test for the diagnosis of pernicious anemia or malabsorption syndrome, 65 studies were selected for clinical correlation. Criteria for pernicious anemia included mean corpuscular volume greater than 100 cu micrometer, serum B12 greater than 100 ng/l, megaloblastic marrow, achlorhydria, reticulocytes greater than 5% on B12 therapy, atrophic gastritis, and elevated serum antibodies to parietal cells or intrinsic factor. Criteria for malabsorption syndrome included: decreased serum B12, folate, and carotene; increased fecal fat; abnormal D-xylose absorption; abnormal radiographic and biopsy findings. 58Co-cyanocobalamin and 57Co-cyanocobalamin bound to intrinsic factor were given orally to fasting patients; 1 mg of nonradioactive B12 was injected intramuscularly within two hours. Aliquots of 24-hour urine samples were counted. If the excretion of 58Co was less than 7% and the 57Co/58Co ratio was greater than 1.7, the test indicated pernicious anemia; a ratio less than 1.7 indicated malabsorption syndrome. Sensitivity, specificity, and accuracy of the dual-isotope Schilling test were 83%, 98%, and 94% for pernicious anemia, and 67%, 90%, and 86% for malabsorption syndrome, respectively.

Vitamin B12 added as a fortificant to flour retains high bioavailability when baked in bread

“…While it is accepted that the isotope in feces represents the unabsorbed vitamin from bread, there was a relatively large amount of urinary 14 C excreted in this study. Previous studies using radiocobalt have shown that urinary excretion of an oral dose of vitamin B12 is far less than 1% of the dose given, ranging from 0.10–0.41% of 56 Co, 57 Co, 58 Co, 60 Co labelled doses in normal subjects [17-21]. In contrast, we found 5 to 37% of the 14 C dose in urine (Table 1).…”

Vitamin B12 Status after Right Hemicolectomy in Bowel Cancer Patients: A Feasibility Study

“…Vitamin B 12 plays a key role in DNA and cell metabolism and long term deficiency can cause severe and irreversible damage. Effects of B 12 deficiency include fatigue, bone marrow suppression, neurological features including stroke, and risk of cardiomyopathy [5][6][7][8]. It has been recognised that B 12 deficiency can cause symptoms of psychosis, mania, memory impairment, fatigue, irritation and personality changes.…”