Unmasking of Neurosarcoidosis

Abstract

Abstract Introduction: Central diabetes insipidus is a rare complication of neurosarcoidosis. In patients with concomitant adrenal insufficiency (AI), the symptoms of Diabetes Insipidus (DI) can be masked. Case: A 55-year-old female with past medical history of sarcoidosis presented to the hospital with hematemesis, nausea and dizziness. She has a past medical history of cardiac sarcoidosis that was revealed on a PET scan done before 10 years for which she was being treated with methotrexate and prednisone. She was off prednisone for a year prior to hospitalization. She underwent an upper endoscopy that showed diffusely erythematous gastric mucosa in the antrum. She was also hypotensive on admission, and she received packed red blood transfusions after which her sodium increased from 145mmol/L to 165mmol/L (Normal: 135-145mmol/L) in 48 hours. Further workup revealed persistent hypernatremia and urine osmolality was 75mOsm/kg H2O. (Normal: 50-1200mOsm/kg H2O). She was also hypoglycemic and hypotensive requiring multiple fluid boluses throughout her hospitalization. This prompted us to perform a random cortisol that came back at 2.1ug/dl (Normal: 3-23ug/dl) and 1.8ug/dl on two occasions. Cortisol Stimulation test was subsequently ordered, but was done only at 30 minutes, and Cortisol increased from 1.8ug/dl to 6.3ug/dl. Free thyroxine was 0.5 ng/dl (Normal: 0.9-1.8 ng/dl) and her TSH was 7.58uIU/ml (Normal: 0.55-4.78uIU/ml). MRI of the brain revealed extensive areas of extra-axial supra-sellar/infundibular nodular homogeneous intense enhancement that is most consistent with neuro-sarcoid. She was started on prednisone 40 mg daily, Desmopressin 0.05 mg twice daily, and levothyroxine as well. Her sodium level normalized and was 137mmol/L at discharge. She followed up later with outpatient Endocrinology and reported around 90lbs weight gain and no more episodes of nausea or vomiting or epistaxis or lightheadedness. Conclusion: The involvement of the hypothalamic-pituitary axis in sarcoidosis is extremely rare and attributes to < 1% of patients with a sellar mass. Small case series have shown that hypogonadism is the most common endocrine abnormality followed by DI. Our patient had a long-standing history of sarcoidosis with her pituitary dysfunction unmasked only on admission for other causes. She did not manifest any symptoms of DI or AI. There have been case reports where the symptoms of DI are masked due to underlying glucocorticoid deficiency. There have been theories that glucocorticoid deficiency impairs renal water excretion by both ADH (Anti-diuretic hormone) dependent and ADH independent pathways. Another notable feature in our case is that our patient presented with primary hypothyroidism. In fact, sarcoidosis has been commonly implicated in auto-immune polyglandular syndromes type 3, which can present with auto-immune thyroiditis more so in females.