The diagnosis of vitamin B 12 deficiency]

In 5 normal persons, 1 patient with pernicious anemia, 5 patients with renal insufficiency in the state of compensation, and in one patient with chronic hemodialysis Schilling tests, activity of 57Co and vitamin B12 serum levels were measured. It was obvicous that activity of 57Co in serum 8 hours after oral application of 0.5 muCi 57Co-vitamin B12 showed reliable results to clear the problem of vitamin B12 malresorption. This method is easier than the Schilling test because the collection of 24-hour-urine is not necessary and an insufficiency of renal function does not influence the result.     

Physician's management of suspected vitamin B12 deficiency.

A retrospective study was undertaken to audit physician''s management of patients with a low serum level of vitamin B12 who were admitted to a university-affiliated teaching hospital during 1 year. Among the 34 patients 13 were proved to have pernicious anemia or vitamin B12 malabsorption, but for 12 of them there were unnecessary delays (several days or weeks) before initiation of investigation and therapy. An additional six patients, who had low serum levels of vitamin B12 and macrocytosis, most likely had true vitamin B12 deficiency, but proper investigation was not done and they did not receive any vitamin B12 or folic acid therapy. In another nine cases unexplained low serum levels of vitamin B12 were not properly investigated, and the patients either did not receive any vitamin B12 therapy or received it without proper documentation of a deficiency. Suggestions for facilitating early detection, investigation and treatment of megaloblastic anemia or vitamin B12 deficiency are given.     

Factors affecting formiminoglutamic acid excretion in vitamin B12 deficiency

1. Formiminoglutamic acid, a product of the catabolism of histidine, is excreted in abnormally large amounts in the urines of vitamin B(12)-deficient rats and of vitamin B(12)-deficient sheep; the excretion is reduced to negligible amounts after administration of vitamin B(12). 2. After administration of certain methyl donors to vitamin B(12)-deficient rats or sheep urinary excretion of formiminoglutamic acid is temporarily decreased. 3. Irrespective of the pteroylglutamic acid status of the animals neither vitamin B(12)-deficient rats nor vitamin B(12)-deficient sheep have the ability to deal efficiently with histidine. 4. In sheep, urinary excretion of formiminoglutamic acid is increased after administration of aminopterin; treatment with pteroylglutamic acid restores the ability of the animal to deal with the catabolic products of histidine. 5. The possible functions of vitamin B(12) and methionine in relieving a virtual deficiency of pteroylglutamic acid are discussed.