Summary: Estimations of serum and marrow plasma muramidase were made in 39 adults with leukaemia. In the 33 patients studied prior to therapy, the absolute levels of marrow muramidase paralleled those of serum muramidase and reflected the type of leukaemia present.
The normal marrow to serum muramidase ratio lies between 1.5 : 1 and 3 : 1 and in only 2 of the untreated patients was the marrow to serum muramidase ratio grossly elevated, being 10 : 1 and 12 : 1. This may be due to excessive intramedullary death of muramidase-containing cells.
Serial studies of this enzyme were carried out in 17 patients and in the majority both the marrow and the serum muramidase levels fluctuated in parallel with the changes in haematological status and returned to consistently normal levels only when patients entered complete remission. In 4 of the 7 patients who entered complete remission there was a transient rise in marrow to serum muramidase ratios following the beginning of chemotherapy.
This study confirms the value of serum muramidase in the diagnosis and assessment of leukaemia. Marrow muramidase levels may occasionally provide extra information on the mechanisms of changes in intramedullary granulopoiesis.
(C) 1973 Royal College of Pathologists of Australasia