In the Baron case study, what was the definitive diagnosis after hypercalcemia and a parathyroid ultrasound?

• A. Left adrenal tumor
• B. Right thyroid carcinoma
• C. Pituitary adenoma
• D. Left-medial parathyroid adenoma

Answer: (D)

Hypercalcemia caused by an overactive parathyroid gland is most often due to a parathyroid adenoma, leading to primary hyperparathyroidism. When the patient has elevated calcium and a parathyroid ultrasound shows a discrete mass in the left medial parathyroid region, that finding localizes the source of excess PTH to a left-medial parathyroid gland. The resulting excess PTH drives the calcium rise, so this combination points to a left-medial parathyroid adenoma as the definitive diagnosis. Other options involve different glands and would not be identified as a parathyroid lesion on this ultrasound, and they don’t fit the context of a parathyroid-origin hypercalcemia.