Discussion
We reported a case of SLE presented with hypoparathyroidism. Acquired hypoparathyroidism results from deficient PTH secretion following surgery, radiation or autoimmune damage to the parathyroid glands, and storage or infiltrative diseases of the parathyroid glands (5). Postsurgical and idiopathic hypoparathyroidism are the most common causes (5, 6). An autoimmune reason for idiopathic hypoparathyroidism (IH) has been suggested because of the close association between IH and other autoimmune and autoantibodies against parathyroid cells antigens. These antibodies include calcium-sensing receptors and mitochondrial antigens in the serum of patients with hypoparathyroidism(6).CaSR senses calcium concentration and stimulates PTH secretion by the parathyroid and calcium reabsorption by the renal tubules. When CaSR is destroyed, PTH secretion and calcium absorption are depleted(7).
SLE associated with hypoparathyroidism is underestimated and usually has subclinical manifestation. Hypoparathyroidism associated with SLE is extremely rare, and to the best of our knowledge, only 10 cases have been reported(8-13). In 80% of cases, hypoparathyroidism presented before or simultaneous with SLE. In 20% of cases, autoimmune thyroid disease co-exists with hypoparathyroidism. Thyroid autoimmunity is more common, reported in 6-60% of SLE patients. Anti-TPO antibody and Hashimoto’s thyroiditis have been reported in up to 33% and 8% of patients with SLE, respectively (1).