Parathyroid score can predict the duration of required calcium supplementation after total thyroidectomy

BACKGROUND Postoperative hypoparathyroidism is the most common complication after total thyroidectomy, owing to unintentional injury or decreased blood flow to the parathyroid glands. Prediction of postoperative hypoparathyroidism would be helpful for surgeons to manage postoperative hypocalcemia. In this study, we scored the discoloration of the parathyroid glands using a new parathyroid scoring system and evaluated the correlation between the parathyroid score and duration of required calcium supplementation after total thyroidectomy. METHODS A total of 316 patients undergoing total thyroidectomy between November 2009 and April 2010 were enrolled in this retrospective study. Parathyroid scoring was performed by one experienced surgeon. The status of each of the 4 parathyroid glands was classified as normal color (3 points), slightly discolored (2 points), dark discoloration (1 point), or loss of the gland (0 points), resulting in possible total scores of 0-12. Serum parathyroid hormone (PTH), serum calcium, and ionized calcium concentrations were measured at 2 hours, 2 weeks, 3 months, 6 months, and 1 year after surgery. Patients were also divided into three groups based on the duration of required calcium supplementation: no required supplementation (n = 260, 82.3%), required supplementation for <6 months (n = 38, 12%), and required supplementation for ≥6 months (n = 18, 5.75%). RESULTS Parathyroid scores were positively correlated with ionized PTH concentrations at 2 hours (r = 0.053, p < 0.001), 2 weeks (r = 0.056, p < 0.001), 3 months (r = 0.032, p<0.001), 6 months (r = 0.072, p < 0.001), and 1 year (r = 0.071, p < 0.001) after thyroidectomy. Parathyroid scores were significantly and inversely associated with the duration of required calcium supplementation (p = 0.001). CONCLUSIONS Parathyroid scores at the end of surgery might be helpful for predicting the degree of postoperative hypocalcemia after total thyroidetomy.