Endocrine Abstracts

Introduction: The most common cause of diabetes insipidus is idiopathic. In some rare cases, it can be secondary to metastasis to hypothalamic–pituitary region.

Case report: We report a case of 68-years-old female patient presented to our clinic with complaints of polyuria and polydipsia. She had medical history of breast adenocarcinoma 6 years ago treated with surgery, neoadjuvant radiotherapy and 8 cycles of chimiotherapy. On physical examination she had no notable pathological findings and the evaluation of daily urine volume was at 12 l/day. Laboratory data showed normal glucose and calcium level with plasma osmolality calculated 301 mosm/kg and hypotonic urine (Urine osmolality = 90 mos/kg). Water deprivation test revealed central diabetes insipidus and desmopressin therapy was started. After the therapy complaints of polyuria and polydipsia disappeared. MRI of the brain showed infiltration of the pituitary stalk compatible with metastases and absence of posterior pituitary bright spot. Further investigation showed multiple pulmonary and hepatic metastasis and the patient was referred to the medical oncology department.

Conclusion: Tumor metastasis to the pituitary gland is a rare condition that should be noted in a cancer patient with diabetes insipidus. A better understanding of its clinical manifestations could lead to earlier diagnosis, appropriate therapy and potentially improving quality of life.