Introduction: Post-surgical hypoparathyroidism is a well known complication of total thyroidectomy. It may occur as transitory hypoparathyroidism that spontaneously recover within a few weeks/months and as permanent hypoparathyroidism needing long-term treatment. Only few cases of hypoparathyroidism newly diagnosed many years after surgery have been reported. We present a patient with hypoparathyroidism that became clinically evident 15 years after the thyroid surgery.
Case report: Female, 32 years old submitted to total thyroidectomy for papillary thyroid carcinoma (pT2N1bM0) in 1998 at another institution. She was referred to our consultation in September/09 for follow-up and remained clinically asymptomatic until March/12, when she was observed in the Emergency Department due to complaints of hand paresthesias and carpal spasm. Severe hypocalcemia (Ca=5.4 mg/dl (8.810.6), Ca2+=0.68 mg/dl (1.151.35)) was diagnosed. She was treated with i.v. calcium gluconate and after resolution of signs and symptoms was discharged on calcitriol, calcium carbonate and cholecalciferol therapy. Due to constipation, she abandoned by her own initiative calcitriol a month later. The analytical study of calcium metabolism revealed postsurgical hypoparathyroidism (PTH=10.2 pg/ml (10.065.0), Ca=4.1 mEq/l (4.25.1), Ca2+=2.04 mmol/l (2.262.64), PO43−=4.6 mg/dl (2.74.5), Mg2+=1.50 mEq/l (1.552.05)). The patient is now asymptomatic on supplementation with calcitriol, calcium and cholecalciferol.
Conclusion: Late-onset hypoparathyroidism appearing years after total thyroidectomy is a rare condition. Symptoms of hypocalcemia may be latent and subtle (such as weakness, tiredness, irritability and depression) and thus attributed to other diseases. Although hypocalcemia typically occur after surgery, progressive atrophy of the parathyroid glands, leading to its insufficiency years after thyroid surgery, may result in a late latent hypocalcemia. Although we lack data on radioactive iodine (I131) therapy and she is not able to ensure us that information, it is another possible factor contributing to late hypoparathyroidism.