SAT-335 New Onset Adult Idiopathic Primary Hypoparathyroidism Concomitant with Severe Aplastic Anemia

Introduction: Primary hypoparathyroidism is a relatively rare cause of hypocalcemia with cases of primary hypoparathyroidism in the US estimated at 24–37 per 100,000 with 75% being due to neck surgery and 25% due to non-surgical causes. The clinical presentation depends on the acuity of development of hypocalcemia and the absolute level of serum calcium. Here is a case of severe hypocalcemia secondary to hypoparathyroidism of unknown etiology followed by the development of severe aplastic anemia.Case report: A 60-year-old Caucasian male presented to our ED with fatigue, tingling, numbness in extremities and was found to have severe hypocalcemia at 6.8 mg/dl and decreased PTH at 11 pg/mL. Calcium levels 8 months prior to presentation were normal. No history of neck surgery, radiation exposure or family history of autoimmune disorders. Initial workup included creatinine, magnesium and TSH were normal. Autoimmune panel (including PTH Abs and CaSR Abs), HIV test, hepatitis panel, serum protein electrophoresis were also negative. Infiltrative causes of hypoparathyroidism including hemochromatosis, malignancy and granulomatous diseases like sarcoidosis were ruled out with tissue sampling and lab workup. Sestamibi scan obtained showed no parathyroid activity in all four glands. Patient was initially treated with IV calcium to improve serum calcium to more than 7.5mg/L and then switched to oral calcium carbonate 500mg TID and calcitriol 0.5mcg BID until the calcium level was brought up to the lower limit of normal. Patient was seen in follow up and was doing well without any adverse effects. Consequently, the patient developed severe aplastic anemia which was treated with steroids and interestingly, has caused a gradual but consistent increase in PTH levels.Discussion: Idiopathic hypoparathyroidism (IHP) is a rare condition with an incidence of 0.02%. IHP can occur sporadically or as part of a familial condition with autosomal dominant, recessive and X-linked recessive patterns. Certain autosomal forms of hypoparathyroidism have mutations in the PTH gene and Calcium-Sensing Receptor (CaSR) gene. The challenging nature of this case is due to the subacute nature of the patient’s presentation along with the lack of a definitive etiology. The patient’s negative family history and older age makes genetic causes less likely, and Abs against PTH and CaSr were also negative. The patient’s diagnosis of severe aplastic anemia has made the case more fascinating, especially since its management with steroids has causes an improvement in the patient’s PTH status. Regardless of etiology, primary hypoparathyroidism is treated with lifelong supplementation of calcium and calcitriol to a goal serum calcium level at the lower limit of normal. Reference: Abate EG,Clarke BL. Review of Hypoparathyroidism. Front Endocrinol (Lausanne). 2017; 7:172. Published 2017 Jan 16