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Abstract Disclosure: F.F. Foo: None. G. Naronowicz: None. M.S. Akula: None. S.W. Holland: None. J. Cheng: None. R. Ong: None. K. Hu: None. K. Chalasani: None. Background: Autoimmune lymphocytic infundibuloneurohypophysitis (LINH) is a potential cause of panhypopituitarism with biopsy being the gold standard for diagnosis. This report illustrates a unique case of LINH, detailing the methods employed in diagnosis and treatment. Case Presentation: A 77-year-old man with a history of myelofibrosis, type 1 diabetes mellitus, and history of Nocardia meningitis requiring craniotomy over 20 years ago presented to the hospital for evaluation of neutropenic fever. On arrival, he was also found to be in diabetic ketoacidosis and was admitted to ICU for intravenous insulin infusion and antibiotics. Over the course of his stay, the patient reported increased urine output which was initially attributed to his hyperglycemia, however his symptoms continued to worsen even when euglycemic. Lab studies revealed serum Na 153 mmol/L, urine osmolarity 215 mOsm/Kg, urine specific gravity =1.005 and a net fluid balance of -6,756 mL over three consecutive shifts, which was consistent with diabetes insipidus. MRI revealed thickening of the infundibular stalk with central hypoenhancement, abnormal increased T2 hyperintense signal, and loss of the normal posterior pituitary bright spot. While LINH was strongly suspected, various alternative diagnoses, including bacterial invasion and chemotherapy-induced effects, were considered and excluded. Due to the abnormal MRI findings, further testing was done to evaluate for other endocrinopathies. These tests resulted in Cortisol: 11.63 ug/dL, ACTH: 41 pg/mL, TSH: 0.07 ng/dL, FT4: 0.74 uIu/mL. The patient was started on levothyroxine for central hypothyroidism in addition to continuing desmopressin. Additionally, copeptin and vasopressin-cell autoantibody were checked as they have been recorded to be potential biomarkers for LINH. The Copeptin and vasopressin-cell autoantibody testing were both negative and unfortunately we were unable to check for the additional biomarker Rabphilin-3A due to laboratory limitations. However, after ruling out other causes, the patient was given a diagnosis of LINH based on imaging and his development of central diabetes insipidus and central hypothyroidism. Conclusion: LINH is a potential cause of central diabetes insipidus. Acknowledging the significance of LINH, despite its rarity, underlines the importance of continued monitoring as other endocrinopathies can develop later on. While biopsy remains the gold standard for diagnosis, alternative approaches such as imaging and biomarkers can facilitate confirmation. Presentation: 6/2/2024
Foo et al. (Tue,) studied this question.