[Hyponatremia induced by high-dose cyclophosphamide therapy: a retrospective cohort study Cyclophosphamide and...

Cyclophosphamide-associated hyponatremia is an uncommon adverse effect. Published reports are inconclusive regarding patients under high-dose therapy.

To determine the incidence of hyponatremia in patients under high-dose cyclophosphamide therapy.

Retrospective cohort of adult patients who received high-dose cyclophosphamide therapy between 2010 and 2014 at the Hospital Italiano de Buenos Aires. The primary end-point was hyponatremia (defined as plasma sodium levels < 135 mEq/L), and secondary end-points were symptomatic hyponatremia, severe hyponatremia (plasma sodium levels < 120 mEq/L).

A total of 96 patients received high-dose cyclophosphamide therapy during the study period. 27 patients met exclusion criteria and accounted for 28.1% , so that 69 patients were included in the primary analysis. Study population mean age was 56.5 years (SD 12.8) and 37.6% were female. The cumulative incidence were as follows: 52% (CI 95% 39¬–64) for hiponatremia, 5.8% (CI 95 % 0 –12) for severe hyponatremia, and 8.7% (CI 95% 1.3–16) for symptomatic hyponatremia. The only independent variable associated with the development of hyponatremia was female gender (OR 3.89, CI 95% 1.02–8.55, p=0.04). Cumulative incidence found in this study appears higher than in previous reports, probably because only patients under high-dose cyclophosphamide therapy were included. Cumulative incidence of severe and symptomatic hyponatremia were lower