Cobalamin and unsaturated transcobalamin values in pernicious anaemia: relation to treatment.

27 patients with pernicious anaemia, followed for a long period, were consecutively treated with 3 different vitamin B12 preparations while, during intervening periods, no therapy was given until signs of B12 deficiency developed. The mean of the vitamin B12-free period lasted 400 d. Some patients were 'short-reactors' whereas others were 'long-reactors'. Some patients repeatedly revealed deficiency signs at cobalamin values greater than 200 pmol/l and others at values less than 50 pmol/l, pointing to individually different cut-off points for appearance of signs of deficiency. Hypersegmentation was the first sign in about 2/3, neuropathy in 1/3 and mucosal changes in about 1/10 of the patients. The same type of deficiency was repeatedly noted in the same patient. The daily decline of plasma cobalamin values decreased during the vitamin B12-free period. In perorally treated patients the unsaturated transcobalamin values showed an inverse relationship to the cobalamin values. Marked increases in unsaturated transcobalamin I values were noted in 4 of 16 patients treated with B12 injections, resulting in prolonged high cobalamin values and prolongation of the vitamin B12-free periods.