Progression of Secondary to Tertiary Hyperparathyroidism with a Coexisting Parathyroid Adenoma in Stage 3b Chronic Kidney Disease: A Case Report.

Tertiary hyperparathyroidism arises when prolonged secondary hyperparathyroidism progresses to autonomous parathyroid hormone secretion with persistent hypercalcemia, most often in chronic kidney disease. Diffuse or nodular multiglandular hyperplasia is the expected pathology; a discrete parathyroid adenoma arising within hyperplastic tissue is uncommon and may be overlooked when imaging is negative early in the disease course. A 60-year-old man with stage 3b chronic kidney disease and long-standing secondary hyperparathyroidism presented with recurrent hypercalcemia and severe vomiting. Laboratory evaluation confirmed elevated serum calcium and parathyroid hormone. Initial cervical ultrasonography showed no parathyroid enlargement, but repeat imaging demonstrated a progressively enlarging lesion adjacent to the left thyroid lobe. He underwent subtotal parathyroidectomy with bilateral cervical exploration. Histopathology showed multiglandular hyperplasia of the right parathyroid glands together with a distinct encapsulated adenoma arising within hyperplastic left parathyroid tissue. Serum calcium normalized postoperatively.