A study on the clinical significance of serum and urinary muramidase activity in leukemics.

A study was made on serum and urinary muramidase in 56 patients with leukemia and other hematologic disorders. Serum and urinary muramidase levels prior to antileukemic therapy were elevated in monocytic leukemia, while not so increased in paramyeloblastic leukemia. In all patients with acute lymphocytic leukemia pretreatment serum enzyme activities were decreased below normal, whereas those in patients with acute myelocytic leukemia were normal or slightly increased. In other hematologic diseases the mean values of serum muramidase levels before treatment were elevated slightly or moderately. Extreme urinary muramidase excretion was found in untreated patients with monocytic leukemia in contrast to none or little amount in the other groups. The serum and urinary muramidase levels changed in close correlation with peripheral leukocyte counts, bone marrow contents and clinical status in patients with monocytic leukemia. When antileukemic therapy was effective, serum and urinary muramidase levels fell toward the normal as leukemic cell counts decreased. During complete remission serum enzyme levels remained within normal range and muramidasuria was never found. Following relapse muramidase levels began to rise. Serum and urinary enzyme activities increased in a patient with monocytic leukemia in whom only a few blastic cells were found in peripheral blood and bone marrow. On the basis of the present results, diagnostic value of serum and urinary muramidase activity and the relationship between the clinical status and the enzyme activity in leukemia, especially in monocytic leukemia, were discussed.