Author's response to reviews Title:Relationship between parathyroid mass and parathyroid hormone level in hemodialysis patients with secondary hyperparathyroidism Authors:

23 Background: To evaluate the influence of parathyroid mass on the regulation of 24 parathyroid hormone (PTH) secretion, we investigated the relationship between the 25 resected parathyroid gland in total parathyroidectomy and the parathyroid hormone 26 level in hemodialysis patients with secondary hyperparathyroidism. 27 Methods: From January 2009 to July 2014, 223 patients undergoing total 28 parathyroidectomy were included. The size and the weight of parathyroid gland were 29 measured during the operation. 30 Results: 874 parathyroid glands were removed. A positive correlation was identified 31 between the size and the weight of resected parathyroid glands. We found that both the 32 preoperative PTH and the reduction of PTH were significantly correlated with the size 33 and the weight of parathyroid glands in a positive manner. However, in the subgroup of 34 patients with PTH<1000pg/ml, no significant correlation was found. 35 Conclusions: Larger parathyroid gland secretes more PTH and high level of serum 36 PTH usually indicated that surgical removal might be required. However, since PTH 37 levels could be influenced by the pharmaceutical drug, the large size of parathyroid 38 gland might be used as a much more appropriate guide that indicates the requirement of 39 surgery treatment even when the parathyroid hormone was less than 1000pg/ml. 40