Early Hypoparathyroidism Reversibility with Treatment of Riedel's Thyroiditis

Riedel's thyroiditis (RT) is a rare, fibroinflammatory condition which induces gradual thyroid gland destruction and adjacent soft-tissue fibrous infiltration. About one- seventh of RT cases are associated with hypoparathyroidism, necessitating long-term therapy for symptomatic hypocalcemia. The reversibility of the parathyroid hormone deficit has not been fully described.

A 40-year-old woman with no prior history of thyroid disease presented with a six month history of progressive thyroid enlargement complicated by worsening dysphagia and positional dyspnea. Her past medical history was remarkable only for retroperitoneal fibrosis. Physical examination revealed a large, hard, non-mobile goiter. Thyroid indices while maintained on levothyroxine were normal, but marked asymptomatic hypocalcemia with an inappropriately normal parathyroid hormone level was noted. Thyroid imaging and fine needle aspiration were consistent with RT. Isthmectomy and subsequent serial corticosteroid and tamoxifen treatment led to rapid symptom improvement. Serum calcium and parathyroid hormone levels returned to the reference range within three months.

We describe a case of RT in which hypoparathyroidism resolved after treatment targeted the mechanical compression and the fibroinflammatory milieu of the patient's thyroidal disease.

RT can be associated with hypoparathyroidism that is clinically silent at presentation. Mechanical decompression of the goiter and immunomodulatory therapy can reverse the fibrosclerotic process and lead to rapid recovery of parathyroid gland function, as in this patient. However, in most cases hypoparathyroidism is persistent and requires continued treatment to prevent symptomatic hypocalcemia.