The number of patients with PTH less than the minimum detection range (1.2 pg/ml) within three days after surgery was 60 (20.8%), 13 (21.7%) of whom developed permanent hypoparathyroidism; only 8 (7.3%) of the remaining 110 patients with hypoparathyroidism developed permanent hypoparathyroidism. This evidence concerns the gene PTH and hypoparathyroidism.