Serum ‘Uracil+Uridine’Levels Before and After Vitamin B12Therapy in Pernicious Anaemia

Abstract

The serum uracil + uridine levels, expressed as uracil, were measured in 10 cases of pernicious anemia both before and after treatment and compared with the levels in 97 normal subjects. The mean pre-treatment value (8.82 .mu.mol/l, range 6.0-12.0 .mu.mol/l) differed significantly from that of the normal controls (15.7 .mu.mol/l, range 5.7-40.5 .mu.mol/l, t = 8.8, P < 0.001). This confirms the low serum uracil level previously reported in pernicious anemia in relapse. The level rose progressively after treatment, reaching a maximum on the 4th day (mean 17.85 .mu.mol/l, range 9.3-23.4 .mu.mol/l). This was not significantly different from the mean of the normal control group. The difference between the pre- and post-treatment levels was significant on days 3, 4 and 5 (P < 0.005, P < 0.001 and P < 0.005, respectively) and the rise preceded the reticulocyte response by 24 h. A further case was treated with physiological doses of vitamin B12 (2 .mu.g daily for 6 days) and a similar rise in the serum uracil level noted. These results are not explained by any of the known functions of vitamin B12. They are similar to the changes in the serum methionine levels previously reported in pernicious anemia. The latter were readily explained by the known action of vitamin B12 on de novo methionine synthesis. The synthesis of uracil, like that of methionine, might be influenced by vitamin B12 in man.