SUN-048 - Endocrine Manifestations of Hypothalamic-Pituitary Neurosarcoidosis

Introduction: Neurosarcoidosis affects the nervous system in 5–10% of sarcoidosis cases, with hypothalamic–pituitary involvement reported in only 0.5–2.5%. Central diabetes insipidus (CDI) is the most common endocrine manifestation, occurring in up to 50–58% of cases and frequently accompanied by anterior pituitary hormone deficiencies.

Case: A 52-year-old man with known neurosarcoidosis presented with encephalopathy, hypothermia (32.5°C), bradycardia (30–40 bpm), and intermittent hypotension. Laboratory evaluation demonstrated hypernatremia (Na 159 mmol/L), elevated serum osmolality, low urine osmolality ( < 100 mOsm/kg), and marked polyuria, consistent with CDI. Brain MRI revealed multifocal edema involving the hypothalamus and periaqueductal region. Cerebrospinal fluid showed markedly elevated protein (459 mg/dL) with negative infectious studies. He was treated with intravenous methylprednisolone followed by an oral prednisone taper. CDI improved with desmopressin, transitioned from intranasal to oral dosing. Thyroid studies showed free T4 0.5 ng/dL with TSH 5.42 µIU/mL, and levothyroxine was initiated. Despite biochemical improvement, bradycardia persisted; cardiac MRI demonstrated infiltrative disease requiring permanent pacemaker placement. A pre-treatment cortisol level was low at 2.4 µg/dL, raising concern for central adrenal insufficiency, though further evaluation was deferred due to ongoing supraphysiologic glucocorticoid therapy. The patient was discharged on desmopressin, levothyroxine, and prednisone with plans for outpatient pituitary axis evaluation.

Discussion: Hypothalamic–pituitary neurosarcoidosis is rare and often results in persistent endocrine dysfunction. CDI commonly reflects irreversible posterior pituitary injury, necessitating long-term desmopressin therapy despite immunosuppression. Assessment of anterior pituitary function is challenging in the acute setting, particularly during high-dose glucocorticoid therapy, which may mask adrenal insufficiency. Thyroid dysfunction may present with atypical biochemical patterns, complicating differentiation between central and primary hypothyroidism. Endocrine deficits rarely recover even with neurologic improvement, highlighting the importance of long-term hormone replacement and structured endocrine follow-up.

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