Introduction: Permanent hypoparathyroidism is a recognized complication of total thyroidectomy, with an estimated incidence of 10.47%. Standard treatment involves supplementation with calcium and activated vitamin D. However, some patients remain refractory to conventional therapy and fail to achieve normocalcemia. During pregnancy, significant physiological changes occur in calcium-regulating hormones. Notably, the placenta increases the production of parathyroid hormone-related peptide (PTHrP), which acts as a calcitropic hormone, mimicking the effects of parathyroid hormone. Case: A 38-year-old female with a history of total thyroidectomy 14 years ago for follicular thyroid carcinoma presented with permanent hypoparathyroidism. Her condition was refractory to high-dose replacement therapy, which included calcium carbonate 3 g BD, alfacalcidol 4 mcg ON, calcitriol 1 mcg BD, and cholecalciferol 100,000 IU OD. Despite compliance, her serum calcium levels fluctuated between 1.7 and 1.93 mmol/L, necessitating intermittent intravenous calcium infusions. Laboratory investigations showed a phosphate level of 1.63 mmol/L and 24-hour urine calcium of 4.81 mmol/L. Her thyroid function remained stable on levothyroxine 150 mcg daily (T4: 12.0 pmol/L; thyroid-stimulating hormone: 2.93 mIU/L). While off-label use of teriparatide was being considered, she became pregnant. As the pregnancy progressed, her calcium levels stabilized. Calcitriol was discontinued at 26 weeks’ gestation when her calcium reached 2.5 mmol/L. By 30 weeks, the alfacalcidol dose was reduced to 3.5 mcg daily, with cholecalciferol dosing reduced to 50,000 IU OD. Her corrected calcium levels remained between 2.4 and 2.6 mmol/L until delivery. Similar reduction in supplementation requirements was noted during her previous pregnancy. Conclusion Elevated PTHrP during pregnancy likely contributed to improved calcium homeostasis by increasing maternal bone resorption and enhancing placental calcium transfer. This case underscores the necessity of individualized, dynamic adjustments to calcium and vitamin D therapy based on rigorous biochemical monitoring for pregnant patients with hypoparathyroidism.
Female ; Pregnancy ; Hypoparathyroidism ; Placenta