[Clinical application of thymidine kinase activity in patients with acute non-lymphocytic leukemia].

An improved method for the detection of thymidine kinase (TK) activity with the use of 125I-iododeoxyuridine as the substrate. Radioimmunoassay of prolifigen TK "Daiichi", was used for this assay. Eighty-seven serum samples were collected from 40 patients with acute nonlymphocytic leukemia in four institutions. The levels of TK were measured in the time of pretreatment, remission, and recurrence, and the relationship between the levels of TK and either LDH, marrow blasts, or circulating blasts was also examined. The levels of TK were significantly lower in the state of remission than in the pretreatment. However, the level of TK in remission was much elevated in the majority of cases than normal range (less than or equal to 5 units/l). On the contrary, LDH in remission was within normal limits in the majority of cases. The level of TK in the state of relapse was significantly higher than in the remission. The level of TK correlated in some extent with the percentage of marrow blasts (r = 0.508), and the level of TK in more than 5% of marrow blast was most beyond normal range. Correlation coefficient between the percentage of circulating blasts and TK (r = 0.577) was slightly higher than that between the percentage of marrow blasts and TK. Correlation coefficient between the level of TK and the number of marrow blasts was higher than that between LDH and number of marrow blasts. The levels of TK correlated well with serum LDH (r = 0.778), and was more sensitive than LDH. In conclusion, it was suggested that TK could be used as one of an useful and supplemental tumor marker in the follow-up of treatment of acute nonlymphocytic leukemia and to monitor the effect of therapy.