Hyponatraemia in cancer: association with type of cancer and mortality.

Hyponatraemia is common in patients with cancer. The objectives of this study are to investigate the severity distribution of hyponatraemia and its association with mortality. We retrospectively reviewed medical records for patients admitted to a national centre for cancer care and research in Qatar between 2008 and 2012. A model was built through multivariate analyses to investigate the role of hyponatraemia in mortality. Patients were grouped into those who had moderate-severe hyponatraemia (Na < 130) and those who only had normal-mild hyponatraemia (Na ≥ 130). A total of 2048 patients were included in this study. Prostate (57.1%), pancreatic (50%), liver (49%) and lung (40.2%) cancers showed the highest frequency of moderate-severe hyponatraemia, while breast cancer showed the lowest frequency at 23.5%. In the multivariate analyses, patients with moderate-severe hyponatraemia (Na < 130 mmol/L) were 4.28 times more likely to die than those with normal-mild hyponatraemia (Na ≥ 130) (P < 0.05). The present study shows that hyponatraemia is a common electrolyte disturbance among hospitalised patients with cancer diagnoses. The severity of hyponatraemia was a statistically significant independent factor associated with higher in-hospital mortality. This is in accordance with the reported literature and emphasises the importance of early diagnosis and correction of hyponatraemia.