Hyponatraemia in cancer patients on an inpatient rehabilitation unit

This study identifies the incidence of hyponatraemia in cancer patients on an inpatient rehabilitation unit and examines the association between admission hyponatraemia and rehabilitation length of stay (LOS), functional outcome, and survival. After institutional review committee's approval, we retrospectively reviewed medical records of 295 consecutive patients who were admitted to this inpatient cancer rehabilitation unit between 27 January 2009 through 31 July 2010 in a tertiary cancer centre. The incidence of hyponatraemia in cancer patients admitted to our inpatient rehabilitation unit was 41.4%. Median rehabilitation LOS for patients with mild (Na 130-134mEq/L) and moderate-severe (Na < 130mEq/L) hyponatraemia was 11 and 15 days, respectively, which was significantly longer than patients with eunatraemia (10 days; P = 0.03). Functional Independence Measure gain for ambulation and transfers during inpatient rehabilitation stay was not significantly different between three different patient groups. We concluded that large portion of patients who require acute inpatient rehabilitation presented with hyponatraemia, which is associated with prolonged rehabilitation LOS. Whether aggressive management of hyponatraemia will shorten rehabilitation stay needs further study.