SAT-084 - Refractory Hypokalemia in the Setting of Metastatic Pancreatic Neuroendocrine Tumor and Positive Dexamethasone Suppression Test

A 62-year-old female with past medical history of obesity and hypertension diagnosed at age 40 presented to the hospital for altered mental status, generalized weakness, and presyncope.

Initial laboratory evaluation revealed hyperglycemia with glucose of 385 mg/dL and A1c of 10.70%. Potassium on admission was 1.8 mmol/L. During her hospitalization, she had persistent metabolic alkalosis, hypokalemia, and hypertension. Urine studies were significant for elevated urine chloride (173 mmol/L), urine sodium (155 mmol/L), and urine potassium (60.3 mmol/L), consistent with chloride-resistant metabolic alkalosis. The patient denied history of diuretic use or licorice ingestion.

After serum potassium was corrected with oral and intravenous supplementation, aldosterone was 3.9 ng/dL, plasma renin activity was 1.105 ng/mL/hr, aldosterone/renin ratio was 3.5, and plasma ACTH was 99.7 pg/mL. Of note, the dexamethasone suppression test was positive.

Imaging revealed a pancreatic and chest wall mass that was biopsied and tested positive for a neuroendocrine carcinoma.

The high urinary potassium and chloride raise concern for a state of real or apparent mineralocorticoid excess, although other considerations include renal tubular disorders, persistent hypokalemia, or physiologic derangements related to underlying malignancy. Paraneoplastic endocrine activity—especially from small-cell neuroendocrine tumors—can mimic hyperaldosteronism. This occurs because excess cortisol or mineralocorticoid-like steroids activate the renal mineralocorticoid receptor, causing renal potassium and hydrogen loss. Given the patient’s metastatic small-cell neuroendocrine carcinoma, this paraneoplastic mechanism is a key consideration.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*