Screening for primary hyperparathyroidism before thyroid surgery: A prospective study.

Background: Misdiagnosed primary hyperparathyroidism (PHPT) during thyroid surgery may lead to a difficult reoperation. Because PHPT is often asymptomatic, calcium measurements have been recommended before thyroid surgery, but no study has focused on the results of a prospective PHPT screening.

Methods: The prospective study of 748 patients consisted of 2-step screening of calcium measurement in all patients (normal range, 2.2 to 2.6 mmol/L, 8.8 to 10.4 mg/dL). If the calcium level was greater than 2.49 mmol/L (9.9 mg/dL), parathyroid hormone level (PTH; normal range, 11 to 65 pg/mL) and second calcium measurements were obtained. Positive screening was defined by 2 calcium levels greater than 2.49 mmol/L (9.9 mg/dL) and PTH level greater than 49 pg/mL. In patients with negative screening, we evaluated the number of parathyroid incidentalomas. In patients with positive screening, we rated parathyroid adenomas discovered as "easily accessible" or "requiring specific dissection." We assumed that the former could have been incidentally found by a surgeon unaware of calcium value. The cost estimation was based on French national health system databases.

Results: In the 9 patients with positive screening, 9 had parathyroid adenomas, 3 of them requiring specific dissection. In the 739 patients with negative screening, 12 had surgical incidentalomas and 2 had postoperative PHPT diagnosis.

Conclusions: Our screening was not exhaustive, but it avoided a reoperation for missed PHPT in 3 patients. Population screening cost less than 3 reoperations. Other strategies, more exhaustive and/or cost-effective, should be investigated.