Endocrine Abstracts

Introduction: Hyponatraemia constitutes the most common hydro-electrolytic abnormality and the determination of its cause is important for patient’s treatment, which can include the use of a pharmacological agent.

Observation: A 78-year-old woman suffering from a lung adenocarcinoma presents a chronic hyponatraemia ranging from 114 to 123 mmol/l, which cannot be corrected by fluid limitation alone. Clinical and biological assessment leads to diagnose a syndrome of paraneoplastic inappropriated secretion of antidiuretic hormone (SIADH). The tumor cannot be surgically removed, as metastases are present. A treatment with demeclocylin 600 mg daily is initiated, with a response within 6 days as natraemia increases to 137 mmol/l, with persistant efficacy at 2 months, and with good tolerance.

Discussion: In the face of a SIADH, the clinician can use few therapeutic strategies like aetiological treatment and fluid limitation. Demecloclycin can be highly efficient, probably due to a cyclic AMP pathway inhibition. Another family of drugs, vaptans or V2 ADH-receptors antagonists show interesting results in case of euvolemic or hypervolemic hyponatraemias.

Conclusion: The use of demeclocyclin has been very helpful for this lady suffering from an advanced stage lung adenocarcinoma, and who cannot benefit from an aetiological treatment, which is usually associated with correction of hyponatraemia. The precise mechanism of the drug is however not well understood yet, and deserves to be elucidated in pharmacological studies.