We present the case of Mr JJ, 46-year-old gentleman who initially presented with a 3-week history of muscle cramps, malaise and paraesthesia correlating with severe hypocalcaemia, hypomagnesaemia and hypoparathyroidism, requiring high doses of oral supplementation. There was no history of neck surgery, nor a personal or family history of autoimmunity. He was diagnosed with idiopathic hypoparathyroidism. He required frequent dose titrations and the addition of a thiazide to reduce urine calcium excretion. Despite his normalising calcium levels, he still experienced significant symptoms and his condition became increasingly debilitating. Given his circumstances, he was unable to afford PTH analogues.
He was referred to rheumatology for review of inflammatory arthritis as he developed bilateral ankle and wrist pain associated with increased inflammatory markers. Around this time, his renal function worsened, prompting a renal biopsy which revealed interstitial nephritis without granulomata. The unifying diagnosis was not apparent, however extra-pulmonary sarcoidosis was a differential, and he was trialled on prednisone among other immunosuppressive therapies. This controlled his arthropathy and over the course of months, also resulted in significantly reduced calcium supplementation and normalising PTH levels.
Surgical hypoparathyroidism accounts for 70-80% of patients with hypoparathyroidism (1). Non- surgical hypoparathyroidism is often labelled idiopathic, however this describes a heterogenous group of conditions which have an underlying genetic or autoimmune basis (2). Autoimmune hypoparathyroidism can occur as an isolated condition or part of a larger autoimmune syndrome such as APS1, with case reports supporting the use of immunosuppressive agents which target calcium sensing receptor (CaSR)-activating antibodies (3,4,5) thereby increasing PTH secretion.
This case highlights ‘idiopathic’ hypoparathyroidism having an underlying autoimmune component, responding well to immunosuppression. This modality of treatment is useful to consider in patients who have suspected autoimmune hypoparathyroidism and are intolerant of calcium supplementation or who suffer adverse effects associated with excessive calcium supplementation.