MON-393 - A Complicated Course to Cure: Incidental Papillary Thyroid Microcarcinoma and Severe Hypoparathyroidism in Graves' Disease

Background:
Graves’ disease is associated with an increased prevalence of differentiated thyroid carcinoma, most commonly papillary thyroid carcinoma (PTC). Occult microcarcinomas may be present despite the absence of discrete nodules on preoperative imaging. Thyroidectomy provides definitive treatment of hyperthyroidism and allows for histopathologic detection of incidental malignancy. Postoperative hypoparathyroidism remains a clinically significant complication with potential need for advanced therapy.

Case Presentation:
A 46-year-old woman with Graves’ disease, previously complicated by thyroid storm, was managed with methimazole after definitive radioactive iodine therapy was not completed due to loss to follow up. Preoperative thyroid ultrasound demonstrated a diffusely enlarged, heterogeneous gland with pseudonodular echotexture and no discrete nodules or abnormal cervical lymphadenopathy.
She underwent total thyroidectomy for definitive management of hyperthyroidism. Surgical pathology incidentally revealed a micropapillary papillary thyroid carcinoma, classic type (pT1a), localized to the right thyroid lobe, with complete resection and no evidence of extrathyroidal extension. Postoperative surveillance showed declining thyroglobulin levels with undetectable thyroglobulin antibodies, consistent with no biochemical evidence of residual disease.
The postoperative course was complicated by severe hypocalcemia due to permanent hypoparathyroidism. Despite conventional therapy with calcium and vitamin D supplementation, biochemical control remained suboptimal. The patient was initiated on recombinant parathyroid hormone therapy (palopegteriparatide), resulting in improved calcium levels and allowing discontinuation of calcitriol and oral calcium supplementation.

Conclusion:
This case underscores the increased risk of papillary thyroid carcinoma in patients with Graves’ disease, even in the absence of nodules on imaging. It also highlights the morbidity of permanent hypoparathyroidism following thyroidectomy and demonstrates the role of palopegteriparatide in achieving calcium stability when standard supplementation is insufficient.

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