Schilling test

Abstract: At one time, the diagnosis of a deficiency of vitamin B12 or folate was considered to be relatively straightforward. As knowledge has accumulated, the limitations of such tests as serum vitamin level measurements and the Schilling test have become apparent. With the development of newer tests, atypical and subclinical deficiency states have been recognized. In this review, available tests used in the diagnosis of vitamin B12 and folate deficiency are discussed, and a rational approach to the diagnosis of these deficiency states is presented. Arch Intern Med. 1999;159:1289-1298 VITAMIN B12 (COBALAMIN) Strictly speaking, vitamin B12 refers to only cyanocobalamin, but several other Cobalamins have identical nutritional properties, and in the hematology literature, the terms cobalamin (Cbl) and vitamin B12 are used interchangeably. Cobalamin is synthesized by bacteria and is found in soil and in contaminated water. Foods of animal origin (meat, eggs, and milk) are the primary dietary sources. The amount of Cbl in the average Western diet (5-15 µg/d) is more than sufficient to meet the recommended dietary allowance of 2 µg/d. Therefore, except in strict vegetarians, the presence of Cbl deficiency implies the presence of an absorptive problem. The body stores a large amount of Cbl (2-5 mg) relative to daily requirements. Therefore, it takes 2 to 5 years to develop Cbl deficiency even in the presence of severe malabsorption. Table 1 summarizes the steps in Cbl absorption and transport. FOLIC ACID (FOLATE) The term folic acid can designate a specific compound, pteroylglutamic acid, but more commonly it is used as a general term for a class of related compounds (also called folates) with similar nutritional activity. Folates are synthesized by microorganisms and by plants and are widely distributed in the diet. Vegetables, fruits, dairy products, and cereals are the most important sources. Americans ingest an average of 200 to 300 µg/d, which is close to the recommended dietary allowance. Unlike Cbl, the body stores of folate (5-10 mg) are small relative to daily requirements. Table 2 summarizes the steps in folate absorption and distribution.

Abstract: Vitamin B12 (cobalamin) deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders. The role of B12 deficiency in hyperhomocysteinemia and the promotion of atherosclerosis is only now being explored. Diagnosis of vitamin B12 deficiency is typically based on measurement of serum vitamin B12 levels; however, about 50 percent of patients with subclinical disease have normal B12 levels. A more sensitive method of screening for vitamin B12 deficiency is measurement of serum methylmalonic acid and homocysteine levels, which are increased early in vitamin B12 deficiency. Use of the Schilling test for detection of pernicious anemia has been supplanted for the most part by serologic testing for parietal cell and intrinsic factor antibodies. Contrary to prevailing medical practice, studies show that supplementation with oral vitamin B12 is a safe and effective treatment for the B12 deficiency state. Even when intrinsic factor is not present to aid in the absorption of vitamin B12 (pernicious anemia) or in other diseases that affect the usual absorption sites in the terminal ileum, oral therapy remains effective.

Abstract: Of 100 patients with atrophic gastritis, 49 were re-examined 10-15 years after the first and 5-8 years after the second examination, 18 patients answered a questionnaire but declined the re-examina...

Abstract: A metabolic and physiological assessment was carried out in 14 patients who had undergone restorative proctocolectomy with ileal reservoir more than six months previously. The haemoglobin was normal in all but one and plasma electrolytes and serum albumin, calcium, phosphorus, and red cell folate estimations were normal in all. Five patients had low serum iron levels of whom one had an iron deficiency anaemia. The 24 hour faecal fat output was normal in all patients and there was no case of vitamin B12 malabsorption as judged by the Schilling test, although four patients had marginally low values. These were not associated with increased bacterial counts in the faeces within the reservoir and there was no evidence to support a diagnosis of stagnant loop syndrome. Inflammation of the reservoir mucosa was, however, associated with higher counts of aerobic bacteria than in cases where inflammation was absent. Subtotal villous atrophy or inflammation was seen in biopsies of the reservoir in six patients. The mean faecal output per 24 hours was 659 +/- 259 g and the mean reservoir volume was 330 +/- 78 ml. Mean resting anal canal pressure was significantly lower in patients with a mucous leakage per anum than in those without, while manometry of the reservoir showed no alteration of pressure over a period of one hour before and after a meal. A positive rectosphincteric reflex was observed in nine patients.