Endocrine Abstracts

Hyponatraemia, the commonest electrolyte disorder in hospitals is associated with increased length of stay, morbidity and mortality. The treatment of euvolaemic hyponatraemia with fluid restriction and demecocycline is ineffective. Tolvaptan, a V2 receptor antagonist is licensed for treatment of SIADH, based on two RCT, SALT 1 and SALT 2 studies. The cost of Tolvaptan restricts its use in NHS hospitals with no clear indications with regards to suitable cases. These case reports may help to position Tolvaptan in hospitalised patients with SIADH where fluid restriction and demecocycline resulted in prolonged stay and morbidity. Case 1–90 year old man admitted with a fall and had low sodium due to SIADH. He had new onset cognitive impairment and gait abnormality and these remained after 4 weeks of fluid restriction and demecocycline but improved with Tolvaptan. Case 2–90 year old lady with history of low sodium (SIADH) with fracture neck of femur had her surgery delayed as her Na remained below 125 despite fluid restriction and demecocycline for 3 weeks. Tolvaptan normalised the Na and facilitated her surgery. Case 3–50 year old lady with terminal cancer of the lung with SIADH had prolonged stay due to symptomatic low Na which responded to Tolvaptan, facilitating discharge to spend her last days with her family. Case 4–60 year old lady with fibrosing alveolitis and SIADH was able to avoid readmissions due to symptomatic hyponatraemia on treatment with Tolvaptan. Fluid restriction is rarely practical and may raise Na by 1 mmol/day on <800 ml restriction, unlikely to be effective if urine Na+K exceed serum Na. Demecocycline lacks efficacy and is nephrotoxic. Tolvaptan does not require fluid restriction and there are no reported cases of pontine myelinosis. Tolvaptan has potential role in, reducing length of stay, avoiding readmission, peri/preoperative use and palliative care in SIADH.

Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.