During serial studies of serum muramidase activity (SMA) over a 4‐year period on 168 patients with leukemia and myeloproliferative disorders (MPD) eight patients—one with polycythemia vera (PCV), one with agnogenic myeloid metaplasia, three with atypical myeloid metaplasia, and three with chronic myelogenous leukemia—developed acute myeloblastic or acute myelomonocytic leukemia (AMML). Onset of leukemia occurred early during the course of the disease and was associated with striking elevation of SMA in all six patients with AMML. Three patients studied in detail had significant hypokalemia possibly related to toxic effects of an excess of muramidase on renal tubules. Seven of the eight patients received therapy, consisting of splenic irradiation, alkylating agents, or both. Rapid rise of SMA in patients with MPD may herald the onset of acute leukemic metamorphosis.
Serum muramidase activity (SMA) was measured in 160 patients with leukemia and various myeloproliferative disorders (MPD). SMA was low in acute lymphocytic leukemia, variable in acute undifferentiated leukemia, normal or increased in acute myelogenous leukemia, while greatly increased in acute monocytic leukemia and acute myelomonocytic leukemia. Most patients with chronic myelogenous leukemia and various MPD had elevated SMA. Unexpected findings were low or normal SMA in 5 of 9 patients with acute promyelocytic leukemia, and normal SMA in patients with refractory anemia associated with hyperplastic marrows.
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