Pitfalls of intraoperative (1–84) parathyroid hormone measurement during surgery for primary hyperparathyroidism in 154 consecutive operations

Abstract Background Rapid intraoperative assay of peripheral blood intact parathyroid hormone (PTH) levels has been proposed to supersede frozen-section analysis and assure complete removal of pathological tissue after unilateral (minimal access) exploration. This is a review of the author's surgical, pathological and rapid PTH assay results. Methods Some 152 patients (26 men) had 154 explorations for primary hyperparathyroidism (HPT) with rapid intraoperative assay of intact PTH at Centre Hospitalier Regional et Universitaire de Lille. Results After neck dissection, before removal of any tissue, the PTH level altered from 11 to 900 per cent of the level at induction of anaesthesia. Decay of blood PTH levels after excision was rapid but some late raised levels may be have been due to a pre-excision increase. Recurrent or persistent HPT was seen in eight patients. This was predicted correctly in two and missed in six by the PTH assay (i.e. PTH greater than 50 per cent at more than 5 min). One Schwannoma and one thyroid nodule were removed resulting in diagnostic drops of PTH. There was no instance of non-hyperparathyroid tissue removal and intraoperative PTH assay. Multiple pathological glands were missed by PTH assay in four patients and predicted in a further two. In five patients the fall in PTH was slow; one was taking lithium, one was in mild renal failure and one had such a high initial PTH level that the assay saturated and it appeared that the results remained static. In 140 operations HPT was identified correctly and excised with a concomitant drop in PTH. Conclusion The intraoperative PTH levels vary markedly in either direction between induction of anaesthesia and the end of dissection. After excision of hyperparathyroid tissue the PTH level normally falls briskly from the postdissection level. The number of patients with a potentially unfavourable outcome is small; these data suggest that rapid intrapoperative PTH assay would have missed further HPT in ten of 14 instances had the surgical strategy been solely dependent on PTH levels. The routine use of intraoperative PTH assay in surgery for primary HPT is therefore questioned.