RESUMEN
That the suggested criteria for diagnosis of polycythaemia vera (PV) are rather complicated, therefore accurate diagnosis of PV from other types of polycythaemia is needed. Serum Vitamin B12 and Vitamin B12 binding proteins were determined in a patients with PV and other 5 patients with secondary polycythaemia. Both serum Vitamin B12 and unsaturated Vitamin B12 binding capacity (UBBC) increased considerably. TCIII and TCI increased also markedly, i.e., 16 and 8 folds, respectively, resulting in a decreased ratio of TCI/TCIII from the normal value of 1.34 to 0.71. Patients with secondary polycythaemia had slightly increased serum Vitamin B12 while serum UBBC, TCI and TCIII levels showed no significant alteration from those of normal subjects. These findings indicated that not only increased serum Vitamin B12 and UBBC but also an increase of TCIII and the ratio of TCIII/TCI are the positive findings in patients with PV. Therefore determinations of serum Vitamin B12 and its binding proteins can be used as a criteria for the differential diagnosis of PV from secondary polythaemia.