Dual Diagnostic Dilemma: Gitelman Syndrome and Incidental Neuroendocrine Tumor in a Young Adult With Refractory Hypokalemia

Abstract

We report the first documented case of Gitelman syndrome coexisting with a metastatic pancreatic neuroendocrine tumor in a 19-year-old male, presenting with severe refractory hypokalemia (K⁺ 1.4-1.7 mmol/L), metabolic alkalosis, and hypomagnesemia. The patient's diagnostic workup revealed inappropriate renal potassium wasting (urinary K⁺ 42 mEq/L), hypocalciuria (urinary Ca²⁺/creatinine ratio <0.1), and elevated fractional chloride excretion (>1%), confirming the diagnosis of Gitelman syndrome. Imaging studies identified a somatostatin receptor-positive Grade 2 pancreatic neuroendocrine tumor (Ki-67 8%) with hepatic metastases, making surgical resection unfeasible. Management comprised high-dose potassium and magnesium supplementation, amiloride, octreotide, and everolimus. On account of disease advancement, initial treatment approaches failed, and peptide receptor radionuclide therapy remained limited for the patient owing to financial constraints. Both Gitelman syndrome and metastatic pancreatic neuroendocrine tumor posed unique challenges that required a coordinated multidisciplinary approach. This case highlights the need for malignancy to be added to the differential diagnosis of persistent electrolyte anomalies. Moreover, it emphasizes the limitations in managing double disease entities in a young individual and the insurmountable hurdles for advanced treatments like peptide receptor radionuclide therapy in underdeveloped nations. This report highlights the importance of further studying the association between the interplay of genetic syndromes (such as Gitelman syndrome) and associated neoplasms, as well as the vital coordination of complex and multidisciplinary management in rare clinical situations.

Keywords: gitelman syndrome; hypertension and therapy; primitive neuroectodermal tumor (pnet); refractory hypokalemia; type 1 diabetes mellitus.

Figure 1. Electrocardiogram changes in a hypokalemic patient

The black arrows indicate U waves

Figure 2. CT abdomen showing pancreatic mass with liver metastasis

CT: Computerized Tomography The red arrows show the pancreatic mass, while the blue arrow shows the hepatic metastatic lesions.

Figure 3. ⁶⁸Ga-DOTATATE PET scan showing SSTR-expressing pancreatic and hepatic and splenic lesions consistent with net

PET: Positron Emission Tomography, ⁶⁸Ga: Gallium-68 (a radiotracer isotope), DOTATATE: DOTA-[Tyr³]-octreotate (a somatostatin analog used for imaging neuroendocrine tumors), SSTR: Somatostatin Receptor, NET: Neuroendocrine Tumor The arrow shows the pancreatic tumor.

Figure 4. Histopathological image of pancreatic neuroendocrine tumor

The black arrows indicate nests of uniform, round-to-oval neuroendocrine cells with salt-and-pepper chromatin and minimal atypia, characteristic features of a well-differentiated pancreatic neuroendocrine tumor (PNET).