Hyponatremia and cancer: Results of a retrospective analysis of 45 patients treated with a short course of low-dose tolvapan.

Abstract

e20705 Background: Hyponatremia in the cancer patient is usually caused by the syndrome of inappropriate antidiuretic hormone (SIADH). Other factors may cause hypovolemic hyponatremia, diarrhea, and vomiting. It’s present in 47% of cancer admissions. Introduction of vaptans acting as V2-receptor antagonists considerably improved the unconvincing results of conventional treatment consisting of fluid restriction potentially combined with sodium supplementation and/or demeclocycline therapy. Methods: We present a retrospective analysis of hyponatremic cancer patients treated with Tolvaptan. 45 patients, [31 men 14 women], median age 69 years old. 31.1 % had lung cancer, 17,6% other tumors, 11,1% colorectal and 11,1% prostate cancer. Histology: 53,3% Adenocarinoma, 15,6% SCLC, 15,2% others and 5,6% Epidermoid.The mean of the lowest sodium level was associated with squamous histology (Na 118 mEq/L). Descriptively, older patients (>66 y) had lower levels of Na compared to those younger than 66y (Na 122 mEq/L vs Na124 mEq/L). Median of Na at diagnosis of hyponatremia was 124 mEq/L,"waiting period" days before starting treatment,1d (SD= 1,745). Duration treatment [ Sodium levels out of risk according to the doctor criteria]. Results: Participants improved significantly after treatment period (p=.000). There were no differences in TOLVAPTAN improvements between patients with ≤ 124 mEq/L vs >124 mEq/L (p=.142), but patients with Na ≤ 124 mEq/L tend to achieved higher levels of sodium at the end of treatment (p=.016). No significant differences between different histology, location, "waiting period", duration of treatment, or age. However, Men significantly improved after treatment with tolvaptan (p=.000) and women do not showed significant changes (p=.753) (women had significantly higher pretreatment sodium level than men (122.4 mEq/L vs. 126.2 mEq/L,(p= .05). Conclusions: Tolvaptan is effective in the treatment of hyponatremia in patients with differents histological cancers especially with levels lower than 124 mEq/L. Tolvaptan had good safety profile with no side effects. A short course of two days and low dose (15mg/p.o./d ) with Tolvaptan restored safe Sodium levels.