Syndrome of inappropriate antidiuretic hormone associated with vinorelbine therapy

OBJECTIVE: To describe onset of syndrome of inappropriate antidiuretic hormone (SIADH) associated with vinorelbine therapy for advanced breast cancer. CASE SUMMARY: A 50-year-old white woman with a history of advanced breast cancer refractory to other treatment modalities was receiving vinorelbine. Blood chemistries revealed severely depleted sodium and potassium concentrations from a normal baseline within a 7-day period. A recheck of blood chemistries confirmed hyponatremia. The patient was admitted to the hospital and treated for SIADH. After successful treatment, she was given demeclocycline prophylactically and rechallenged with vinorelbine without recurrence of the syndrome. DISCUSSION: SIADH has been reported as a complication of treatment with vinca alkaloids. To our knowledge, this is the first report of this syndrome related to vinorelbine therapy. CONCLUSIONS: Because of its structural similarity to the other vinca alkaloids, vinorelbine is believed to be responsible for SIADH in our patient. Clinicians should be aware of the possibility that vinorelbine may cause SIADH and possibly hypokalemia.