Interesting and Rare Case of Central Diabetes Insipidus in a Patient With Acute Myeloid Leukemia

Introduction: Central Diabetes Insipidus (CDI) is the lack of antidiuretic hormone (ADH) leading to impaired urinary concentration and manifests with extreme thirst and excessive urination. Patients unable to drink fluids are at risk of severe dehydration and hypernatremia. CDI can be a rare complication of acute myeloid leukemia (AML). The occurrence of AML with CDI is extremely rare with only few case reports published. This combination of AML with CDI has been reported to be associated with monosomy 7 and inversion (3) (q21q26) and portends an overall a very poor treatment response resulting in poor outcomes. Case Presentation: 66-year-old female with hypertension, polycythemia vera diagnosed in 2006 with transformation to AML in 2020. FISH studies revealed monosomy 7. Cytogenetic studies showed inv (3)(q21q26.2). Remission induction chemotherapy was initiated. Subsequently, neutropenic fever and sepsis secondary to Clostridium difficile colitis lead to hospitalization. Her sodium (Na) level gradually trended up and reached a peak of 157 mmol/l (range 136-145) and elevated serum osmolality at 311 mOsm/K with low urine osmolality 135 mOsm/K, low urine sodium at 13 and low urine specific gravity 1.006 concerning for CDI. She developed polyuria and received desmopressin (DDAVP) leading to improvements in urine osmolality to 267 mOsm/K, 30 minutes indicating CDI diagnosis. Her Na gradually normalized to 144 mmol/l, urine osmolality improved to 580 mOsm/K and urine specific gravity to 1.025. She is now on DDAVP 0.05 mg oral twice daily and her Na is in normal range. MRI pituitary did not show any evidence of metastatic lesion with intact pituitary bright spot. Her other pituitary hormonal workup was normal except for hypogonadotropic hypogonadism. Discussion: The pathophysiology of AML and CDI is unclear. Leukemic cells infiltration of the neurohypophysis; thrombosis of small vessels in hypothalamic nuclei and the posterior pituitary; alterations of the neutrophil migration placed on the chromosome 7 leading to glycoprotein gp 130 production, a cell surface marker on granulocytes are some of hypothesis suggested. CDI has a variable onset in the course of myeloid malignancies. MRI pituitary can be normal in most of the cases.