Hematologic responses and concentration of vitamin B12 in serum and urine following oral administration of vitamin B12 without intrinsic factor.

By G. I. M. Ross, M.B., Cri.B. D.C.P.,* D. L. MOLLIN, B.SC., M.B., Cnl.B., E. V. Cox, B.Sc., M.B., B.S., AND C. C. TJNGLEY, M.D., M.R.C.P.* T LIE ABSORPTIOX from the imnt.cstinal tract of small doses of n-itaminn B,2 is impaired inn paticnnts with pernicious anemia. Small doses such as 5 g. gin-cnn daily by mouth produce little or rio hematologic respomise, unnless gin-cnn ssit.in a source of inntrinisic factor’ 2; larger oral doses arc frequenntly effectin-e es-en if gin-cnn without intrinsic factor. lois-ever, paticnnts appear to n-ary is-idely inn their’ ability to absorb the vitamin. For instance, daily doses of as little as 25 g. of nitaminn B12 are reported to have produced ann optimal hematologic responnsc inn a patient with pernicious anemia2; on the other hand daily doses of as mucin as 250 g. of vitamin B,2 has-c beenn ineffectin-e inn some patiemits.3 Very large doses arc much more regularly effective, excellent. clinical amid hematologic rcspomnses being reported by Urnglcy4 inn patienits gin-cnn simigle oral doses of 3000 Mg. of the n-itaminn. Though in a fewpatiennts the response ivas equin-alenit to that. produced by ann inntramuscular injection of 160 .sg. of B,2 or more, the an-erage hematologic rcsponnse is-as equin-alennt t.o that produced by intramuscular injections of about 20 to 40 g. of vitamirn B,2 suggesting that. this is-as tine as-crage amounnt absorbed from the gast.rointcstiinal tract. Xevertheless, the amount of vitannili B,2 excreted after such doses has beenn reported as either unidetect.able by Connley, Kres-anns, Chow, Barroiss, amid Lanng5 or very lowby Chestcrmann, Ciithbcrtsomi, amid Pegler.6 These results arc considerably less than those expected after intramuscular injections of vitamin B12 having a comparable hematobogic effect. It seemed, therefore, that there is-as a differemnce inn the rate or quality of absorption of Bn2 nvhemn gin-cnn by mouth amid nshern given by innjcctionn. Vitamin B,2 inn serum earn be measured by microbiologic assay.7 ‘ 8 Usilng Euglena gracilis var. bacillaris as test organnism nyc nvere able to demonstrate absorption of vitamini B,2 from the gastrointestinal tract by folloising the chamiges in B12 concentrationis inn 1)0th serum arid urine in patients -with pernicious anemia gin-cnn doses of 500 to 3000 jig. by mouth.9