Measurement of parathyroid hormone in patients with primary hyperparathyroidism undergoing first and reoperative surgery

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Abstract
Background: The distinction between solitary parathyroid adenoma and hyperplasia can sometimes be difficult during surgery for primary hyperparathyroidism (pHPT), especially in patients who have undergone previous thyroid or parathyroid surgery. The use of intraoperative parathyroid hormone (PTH) monitoring as a possible diagnostic tool was therefore investigated. Methods: Intraoperative levels of PTH were measured in 119 patients during 121 operations (including 14 reoperations) for pHPT. The mean(s.d.) preoperative serum calcium level was 2·79(0·21) mmol/l. Blood samples were drawn before, and at 5 and 15 min after, excision of the first enlarged parathyroid gland. PTH was analysed electively in 61 patients and on-line by a modified assay for intact PTH in 48 patients. Both procedures were used in ten patients. Results: The mean(s.d.) decline in PTH concentration in 101 patients with primary exploration due to solitary adenoma was 63(17) per cent after 5 min (n = 84) and 83(10) per cent after 15 min. The patients with primary exploration because of multiglandular disease (n = 6) were correctly predicted not to have parathyroid adenoma. Conclusion: Measurement of PTH levels during surgery for pHPT is a highly sensitive method for differentiating between single and multiple gland disease. The on-line monitoring of PTH is clinically useful in patients who have undergone previous neck surgery. Its role in pHPT surgery at primary exploration should be evaluated in prospective trials.