PSAT181 Amyloidosis as a Possible Cause of Hypoparathyroidism

BACKGROUND: Hypoparathyroidism is a relatively uncommon metabolic disorder with an estimated prevalence of 37 per 100,000 person-years in the United States. Postsurgical hypoparathyroidism is the most common etiology and accounts for 75% of the cases. Nonsurgical cases are frequently the result of autoimmune or genetic disorders. Rarely parathyroid gland infiltration, external radiation treatment is also known cause hypoparathyroidism. We present a rare case of hypoparathyroidism associated with amyloidosis. CASE: 61-year-old female presented for evaluation of hypothyroidism and hypoparathyroidism and significant fatigue. Patient was already treated with levothyroxine as well as calcitriol at the time of presentation for management of these issues without improvement in her fatigue. Further review of prior records showed progressive decline in kidney function and albumin, hypothyroidism in addition to worsening hypocalcemia evidenced on ionized calcium levels over a two year period. This also coincided with the duration of the onset of fatigue. Past medical history was also significant for parathyroid surgery for primary hyperparathyroidism 12 years prior to the onset of symptoms. Patient did not develop hypoparathyroidism after surgery but maintained normal calcium levels until onset of symptoms 2 years ago.Physical exam did not reveal any abnormalities. Labs (when patient was receiving calcitriol) revealed a calcium of 9.5mg/dL (8.4-10.2mg/dL), with albumin 2.3g/dL(3.8-5.3g/dL), ionized calcium 1.27mmol/L(1.14-1.33mmol/L), 25-hydroxy Vitamin D 14ng/mL(>/=30ng/mL), PTH 7pg/mL(15-88pg/mL), Phosphorus 3.4mg/dL(2.4-4.8 mg/dL), Magnesium 2.6mg/dL(1.8-3.0 mg/dL), Creatinine 2.45mg/dL(0.40-0.99 mg/dL), eGFR 21 mL/min/1.73m2. She was trialled off calcitriol to assess for improvement of her PTH, however was noted to have inappropriately normal PTH despite hypocalcemia and was restarted on calcitriol. TPO antibody and 21 hydroxylase antibody levels were not elevated. Due to CKD, She underwent kidney biopsy that revealed lambda light chain amyloidosis. Patient is currently receiving daratumumab and Cyclophosphamide-Bortezomib-Dexamethasone and plans to undergo stem cell transplant in future. CONCLUSION: Notably, the occurrence of amyloidosis with hypothyroidism and infiltrative amyloid goiter is well documented. Although prior case studies have detailed the co-occurrence of hyperparathyroidism and amyloidosis, little is known about the relationship of parathyroid disease and amyloidosis. Due to the temporal association of amyloidosis, hypoparathyroidism, and hypothyroidism, we hypothesize that infiltration of these endocrine glands by amyloid has contributed to the dysfunction. The patient will be monitored for improvement in her parathyroid function as the amyloidosis is treated. Further studies are needed to assess the interplay between the parathyroid and amyloidosis. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.