Clinical versus laboratory tumor lysis syndrome in children with acute leukemia.

Renal and metabolic complications of tumor lysis syndrome (TLS) were recognized frequently in the 1960s and 1970s. Strategies were designed to prevent TLS. We conducted a retrospective chart review study to identify the current TLS risk in children with acute leukemia. Children were considered to have "laboratory tumor lysis syndrome" (LTLS) if two of the following metabolic changes occurred within 4 days of the start of chemotherapy: a 25% increase in serum phosphate, potassium, uric acid, or blood urea nitrogen levels, or a 25% decline in serum calcium concentration. Clinical TLS (CTLS) was defined as LTLS plus a serum potassium level higher than 6.0 mmol/L or acute renal failure. Twenty-one of 30 children developed LTLS; one developed CTLS. Absolute blast count, pretreatment white blood cell count, pretreatment lactic dehydrogenase, and sex or tumor DNA index did not correlate with the development of LTLS. LTLS is still frequent in children undergoing chemotherapy for acute leukemia; CTLS, however, is much less common.