SUN-403 Drinking Water from a Dirty Prison Sink: A Rare Case of Acute Myeloid Leukemia with Diabetes Insipidus and Panhypopituitarism

Panhypopituitarism is an extremely rare disorder in acute myeloid leukemia (AML) with only 6 cases previously reported to date. The mechanism of AML causing panhypopituitarism is unclear, but some of the leading hypotheses support leukemic infiltration or leukostasis. A 30-year-old incarcerated woman with a history of intravenous drug use and hepatitis C presented with 5 days of fevers, vomiting, and progressive abdominal pain. She reported an unintentional 30 lb weight loss and a month of polyuria and polydipsia severe enough to cause her to drink water from the dirty sink in her prison cell. Patient denied headache, visual disturbance, or galactorrhea. Initial laboratory studies showed a white blood cell count of 350K with 90% myeloblasts, consistent with AML. She received emergent leukocytapheresis and was started on cytarabine and daunorubicin chemotherapy. Upon admission, she was also noted to have hypernatremia (Na 152 mmol/L), persistent hypotension (BP 80s/40s) unresponsive to fluid resuscitation, and high urine output of 5-14 L/day. Desmopressin (DDAVP) 4 mcg IV was administered and resulted in increased urine osmolality from 116 to 451 mOsm/L with significant decrease in urine output, consistent with central diabetes insipidus (cDI). Brain MRI showed heterogeneous thickening of the infundibulum and an absence of the posterior pituitary T1 bright spot, which can be seen in cDI. Hormonal evaluation revealed low free T4 0.77 ng/dL (ref. 0.93-1.70) and normal TSH 4.03 mIU/mL (ref. 0.27-4.20), consistent with central hypothyroidism. Prolactin was mildly elevated at 39 ng/mL (ref. 4.8-23.3). She was also noted to have low AM cortisol 3 µg/dL (ref. 5-20) prompting a cosyntropin stimulation test which showed baseline cortisol of 5.9 rising to 13.2 µg/dL, which is an inadequate response. She was treated for panhypopituitarism with hydrocortisone 50 mg IV Q8H tapered gradually to a replacement dose, DDAVP 50 mcg PO QHS, and levothyroxine 50 mcg PO daily. Her remaining hospital course was complicated by neutropenic fever. She was ultimately transferred to Massachusetts General Hospital on hospital day 19 (Day 16 of chemotherapy) to be closer to her family. This is a rare case report of a young patient with new diagnosis of AML presenting with both cDI and panhypopituitarism. The mechanism remains unclear. One possible rationale is pituitary stalk involvement by leukemic infiltration which is evidenced by a thickening appearance on MRI. Another explanation is an ischemic or thrombotic effect related to hyperleukocytosis. The resulting hyperviscosity and subsequent disruption of hypophyseal portal capillary flow can impede release of hypothalamic hormones destined for the pituitary. Our patient had MRI findings of an abnormally thickened stalk and lack of “bright spot” which supports the hypothesis of leukemic infiltration and significant disruption of the hypothalamic-pituitary axes.