LACTATE-DEHYDROGENASE LEVELS DURING MACOP-B CHEMOTHERAPY FOR NON-HODGKINS-LYMPHOMA

Lactate dehydrogenase (LD) levels rose consistently during MACOP-B che motherapy for intermediate and high-grade non-Hodgkin's lymphoma (NHL) . Levels peaked at week nine and fell to normal within six weeks of co mpletion of therapy. Isoenzyme patterns, studied prospectively in seve n patients, showed a parallel rise in LD1 and LD2 suggesting a source other than tumour tissue for the rise in total LD. In the absence of e vidence of myocardial or renal damage, haematopoietic tissue was the m ost likely source. With no evidence of haemolysis, normal serum levels of vitamin B12 and folate and normal red cell folate, dyserythropoies is was considered to be the underlying mechanism. A rising mean corpus cular volume further reinforced this suggestion. Intensive use of meth otrexate along with co-trimoxazole as prophylaxis against pneumoycysti s carinii is considered the most likely cause of marrow dysfunction. F ailure to recognise that rising LD levels during such therapy is treat ment-related, rather than of tumour origin, may lead to inappropriate change or abandonment of therapy.