Endocrine Abstracts

Introduction: Hyponatremia is the most common electrolyte imbalance among hospitalised patients. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is considered the most frequent etiology on patients with euvolemic hiponatremia. Conventional treatment includes water restriction and salt tablets with limited efficacy and very slow onset of action in certain patients.

Material and methods: Systematic sampling of all SIADH patients treated with tolvaptan (group A, n=12) in our service over the last 2 years was compared to 12 within the conservative treatment group (group B). The average age was similar in both groups (A: 71.8 years vs B: 71.6 years) with a clear male predominance in the whole sample. The average plasma sodium was also similar (A: 123.4 mmol/l vs B: 123.8 mmol/l). SIADH etiology was mainly neurosurgical (A: nine patients and B: seven patients).

The length of hospital stays was compared with the time span until natremia normalization in both groups. The variables are expressed as mean±S.D. The statistical analysis used was Student’s t-test. P value <0.05 was considered significant.

Results: The length of hospital stay from the beginning of the treatment was 11.1±8.1 days in the tolvaptan-treated group and 16.7±11.5 days in the conservative-treatment group (P=0.18). The mean hospital stay was higher for those treated with conservative therapy. Normalisation of natremia took 2.7±2.7 days in the tolvaptan-treated group and 11.3±9.4 days in the conservative-treatment group. The speed of correction of the hyponatremia was statistically significant for those in the tolvaptan-treated group (P=0.04).

Conclusion: Tolvaptan treatment in SIADH patients shows a rapid normalisation of natremia, effectively reducing inpatient length of stay.