Endocrine Abstracts

Tolvaptan is an ADH antagonist licensed for the treatment of the syndrome of inappropriate ADH secretion (SIADH). We describe the case of a patient with severe symptoms due to refractory SIADH who was successfully treated with tolvaptan. A 35-year old patient developed a chordoma involving the pituitary gland and optic chiasm and was treated with surgery, radiotherapy and gamma knife therapy. After several years, she developed recurrent, severe, symptomatic hyponatraemia due to SIADH which presented with seizures, anorexia and abdominal symptoms. She had typically around 6 admissions per year with hyponatraemia and the symptoms were sufficiently severe that the patient was unable to mobilise or self-care. The SIADH was diagnosed biochemically and was refractory to conventional treatments (demeclocycline, fluid restriction). During one admission, tolvaptan treatment was commenced following 16 days’ unsuccessful conventional treatment. Tolvaptan caused a steady rise in sodium concentrations from 123 mmol/l to 136 mmol/l (reference range 135–145 mmol/l) over four days with a maximum daily increase of 6 mmol/l. No side effects were reported and there was no elevation in creatinine, rebound hypernatraemia or dehydration. She was discharged 5 days later to continue tolvaptan in the community. Nine months later, she remains on tolvaptan, is mobile and self-caring, and has had stable sodium levels in the community and no hyponatraemia-related readmissions. Successful treatment, while costly, has prevented other health care related expenses associated with repeated hospitalisations and social care.

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.