Endocrine Abstracts

Aim: To estimate the prevalence and clinical significance of hyponatraemia in patients with lung cancer.

Methods: The data were obtained from Hospital Registry. The serum sodium (SNa) on diagnosis was used for statistical comparisons. Normonatraemia is defined as SNa 135–144 mmol/l, hyponatraemia <135 mmol/l, and hypernatraemia >145 mmol/l. The data was analysed for small cell (SCLC), non-small cell (NSCLC) and unknown group where histological diagnosis was not possible due to clinical reasons. Data analysis by STATA, version 12.1.

Results: The study population was 314 (57.3% males and 42.7% females). There were 16.4% SCLC, 60.1% NSCLC, and 23.5% unknown group. The sex distribution in SCLC – 52.9% males and 47.1% females, NSCLC – 59.4% males and 40.6% females, and unknown – 56.2% males and 43.8% females. The mean age in SCLC 69.1+10.2, NSCLC 69.7+9.7, and unknown 70.3+13.8 (P=0.84). The overall incidence of hyponatraemia, SNa <135 mmol/l was 37.6%. The incidence of hyponatraemia was higher in SCLC than other two groups but not statistically significant (P=0.09) (SCLC 49.0%, NSCLC 33.2%, and unknown 41.1%). Analysis according to severity of hyponatraemia between groups. Normonatraemic (135–144) 60.5%, mild (130–134) 21.7%, moderate (120–129) 15.3%, severe (<120) 0.6%, and hypernatraemia (≥145) 1.9%. Distribution of hyponatraemia among groups were as follows: SCLC mild 27.5%, moderate 21.6%, and severe 0% ; NSCLC: mild 19.8%, moderate13.4%, and severe 0%. The risk of death within 30 days was 43% higher in the hyponatraemic group than the normonatraemic, not statistically significant. Normonatraemia 37.9%, hyponatraemia 46.6%, and odds ratio (95% CI) 1.43 (0.90–2.28); P=0.13. The risk of death within 30 days in the mild and moderate groups increased by 46 and 27% respectively compared to normonatreamia but not statistically significant. Within 30 days – normonatremia 117/190 (61.6%), mild 36/68 (52.9%), moderate 27/48 (56.3%), and severe 0/2. Odds ratios: normonatraemia 1.00, mild 1.46 (0.83–2.55), P=0.19; moderate 1.27 (0.67–2.42), P=0.46, and severe NA.

Conclusions: Hyponatraemia is a negative prognostic indicator in lung cancer patients. Further studies are needed to see whether correction of hyponatraemia has any survival benefit.

Disclosure: The presenting author has received educational grant from Otsuka.