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Polydipsia-Polyuria Syndrome (PPS) can represent central diabetes insipidus (CDI), nephrogenic DI (NDI), or primary polydipsia (PP). Correct differentiation is crucial for management decisions and prognostication since the wrong treatment can have dangerous consequences. The recent introduction of blood Copeptin measurement has largely simplified this differential diagnoses. We describe an Alzheimer patient presenting with PPS, hypernatremia, together with subsequent documentation of hypercopeptinemia. Is this a new combination syndrome?
Case report.
A 76-yo female with history of Alzheimer’s disease, ischemic cardiomyopathy, HFrEF with an EF of 35-40% CKD, GERD, and multiple myeloma (in remission, since 1997) was evaluated in the ED for dizziness, fatigue, incessant thirst, and chest pain. She was drinking excessively from public faucets when she was outside the house and in the bathroom when she was at home. She used diapers and was discovered to be voiding very frequently and was often dumping her wet diapers, initially, unbeknownst to the daughter. Two days prior, she started Bactrim for UTI. She was in no distress, afebrile, no edema and the physical exam was unremarkable. Pulse 110/min. Sitting BP 124/73 mm Hg. BMI 18.48. Weight 53.5 kg. Sodium 158 mmol/L, BUN 178 mg/dL, creatinine was higher at 1.46 mg/dL, troponin was 0.041 (<0.034) ng/mL and BNP was 2000 pg/mL. Chest radiograph was normal. Non-contrast head CT showed no acute changes. LVEF was 40-45% with diffuse hypokinesis. She received IV D5W and was allowed to drink to thirst (Figure 1).