Polyuria-Polydipsia in Pregnancy: A Case Report of Newly Diagnosed Arginine-Vasopressin Deficiency and Cushing Disease

Introduction: Polyuria and polydipsia during pregnancy can often present a diagnostic challenge due to the physiological changes inherent to gestation. Persistent, disruptive symptoms necessitate thorough investigation. We report a case of a pregnant woman with polyuria and polydipsia in the second trimester, unveiling arginine vasopressin deficiency and Cushing's disease, rare endocrine disorders. Case Description: 30-year-old G5P3A1 at 16 weeks gestation with hypertension presented with excessive thirst and urination for about 4 weeks before admission. Vital signs were remarkable for elevated blood pressures. Physical exam revealed round facies, dorsocervical fat pad, facial and chest acne, hirsutism, and diffuse purple striae. A systolic murmur was also noted. Laboratories showed hyperglycemia (305), hypernatremia (154), hypokalemia (2.2), and metabolic alkalosis (34) with a urine output of 11 liters/day. Urine workup indicated low specific gravity: 1.002 and osmolarity: 100 mOsm/kg. Elevated nocturnal salivary cortisol (35 ng/mL) and ACTH levels (132 pg/dL) were noted. Initial treatment involved fluid and potassium replacement, followed by a single dose of IV desmopressin 4mcg, leading to improved hypernatremia and polyuria (3 liters/day, urine osmolarity: 630 mOsm/kg), indicating arginine vasopressin deficiency (previously known as central diabetes insipidus) along with concomitant Cushing’s disease. Pregnancy termination did not resolve polyuria. While on intranasal desmopressin (10mcg q8 hours), she developed shortness of breath and pulmonary congestion. Severe mitral regurgitation was detected on 2D-echo, necessitating reduced desmopressin frequency to allow increased diuresis. Abdominopelvic CT was unremarkable, but brain MRI revealed a pituitary macroadenoma, scheduled for neurosurgical removal. Discussion: This case underscores the diagnostic challenges posed by polyuria-polydipsia symptoms during pregnancy and emphasizes the importance of thorough investigation in such cases. It highlights the intricate interplay between pregnancy and endocrine disorders, which are rare yet significant contributors to polyuria-polydipsia presentations. Prompt recognition and management are crucial to mitigate complications and improve outcomes