Hyponatremia of non-small cell lung cancer: Indian experience

Hyponatremia is a hazardous complication of lung cancer and its treatment. It is seen at presentation in approximately 15% of patients with small-cell lung cancer (SCLC) and 1% of patients with non-small cell lung cancer (NSCLC). Platinum compounds used as first-line agents along with taxols frequently cause hyponatremia. Till date there is no data on its prevalence in patients with advanced lung cancer in the Indian subcontinent.

This study was undertaken to find out its incidence before and after institution of chemotherapy and to observe the results of treatment of hyponatremia in a group of lung cancer patient.

Forty patients with advanced lung cancer (25 patients with stage III disease and 15 with stage IV disease) were included in the study. Variables looked at included, but were not limited to, serum sodium, serum albumin, serum alkaline phosphatase, serum lactate dehydrogenase, and hemoglobin. These variables were measured as per the standard clinical laboratory procedure. No ethics approval was required as these parameters are routinely measured in such patients.

In the chemo-naïve state, one out of five cases with SCLC (20%) had hyponatremia at presentation; among the 35 cases of NSCLC, 7 patients (20%) had hyponatremia at presentation, which is in sharp contrast to earlier reports of 1% prevalence of hyponatremia in this group. Among the 27 cases who died within 6 months, 11 had hyponatremia; this finding was statistically highly significant.

In India, NSCLC patients are at high risk of having hyponatremia at presentation and this is significantly associated with a worse outcome.