Abstract
SUMMARY: Central diabetes insipidus (CDI) is a rare manifestation of acute myeloid leukemia (AML) with unclear etiology. When present, CDI in AML has most often been described in patients with chromosome 3 or 7 aberrations and no abnormalities on brain imaging. In this case, we present a woman with newly diagnosed AML t(12;14)(p12;q13) found to have diabetes insipidus (DI) with partial anterior pituitary dysfunction and abnormal brain imaging. While in hospital, the patient developed an elevated serum sodium of 151 mmol/L with a serum osmolality of 323 mmol/kg and urine osmolality of 154 mmol/kg. On history, she reported polyuria and polydipsia for 5 months preceding hospitalization. Based on her clinical symptoms and biochemistry, she was diagnosed with DI and treated using intravenous desmopressin with good effect; sodium improved to 144 mmol/L with a serum osmolality of 302 mmol/kg and urine osmolality of 501 mmol/kg. An MRI of the brain done for the assessment of neurologic involvement revealed symmetric high-T2 signal within the hypothalamus extending into the mamillary bodies bilaterally, a partially empty sella, and loss of the pituitary bright spot. A pituitary panel was completed which suggested partial anterior pituitary dysfunction. The patient's robust improvement with low-dose desmopressin therapy along with her imaging findings indicated a central rather than nephrogenic cause for her DI. Given the time course of her presentation with respect to her AML diagnosis, MRI findings, and investigations excluding other causes, her CDI and partial anterior pituitary dysfunction were suspected to be secondary to hypothalamic leukemic infiltration. LEARNING POINTS: Leukemic infiltration of the pituitary gland is a rare cause of central diabetes insipidus (CDI) in patients with acute myeloid leukemia (AML). Patients with AML and CDI may compensate for polyuria and prevent hypernatremia with increased water intake. AML-associated CDI can require long-term desmopressin treatment, independent of AML response to treatment.