Acute central nervous system complications and ammonium levels in adult patients with acute lymphoblastic leukemia receiving l-asparaginase

We analyzed ammonium levels and acute central nervous complications in adult patients receiving chemotherapy for acute lymphoblastic leukemia with or without asparaginase (l-asp). Twenty patients with a median age of 40.3 years were included. Ammonium-levels were measured during 88 chemotherapy cycles, 60 cycles (68%) with l-asp, and 28 cycles (32%) without l-asp. Ammonium was elevated in 87% of all l-asp containing cycles, with median ammonium levels of 169mol/l (interquartile range (IQR) 91-269mol/l). These values were higher when compared to ammonium levels at baseline (31.5mol/l, IQR 24-40mol/l, p<.001), and when compared to levels in cycles without l-asp (30mol/l, IQR 19-41mol/l, p<.001). Acute hyperammonemic encephalopathy was diagnosed in one patient, and encephalopathy for other reasons, but with hyperammonemia as a possible contributing factor in four patients. In conclusion, ammonium levels are elevated in all adult patients receiving l-asparaginase, but only some patients will present symptoms of encephalopathy.