PTH and secondary hyperparathyroidism: We previously reported that secondary hyperparathyroidism is a significant risk factor for developing postoperative hypocalcemia in patients undergoing total thyroidectomy for Graves’ disease.2,10) Here, we present a case in which preoperative native vitamin D supplementation resulted in an unexpected increase in PTH levels, possibly due to an increased skeletal calcium demand, followed by transient hypocalcemia after surgery.