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Screening for parathyroid tumors before thyroid surgery

(July 2002)

The background of the study. Patients with thyroid disorders may also have parathyroid tumors. The tumors may be identified preoperatively, but more often they are discovered by chance during thyroid surgery. This study evaluated the utility of screening for parathyroid tumors in patients undergoing thyroid surgery.

How the study was done. All 748 patients with thyroid disorders referred to one surgeon during a two-year period were screened for parathyroid tumors by measurement of serum calcium. In patients with a high serum calcium concentration, serum calcium and parathyroid hormone (PTH) were measured. Positive screening was defined as high serum calcium and PTH values.

In the patients who had a normal serum calcium concentration, the surgeon looked for parathyroid glands near the thyroid, but looked no further if none were seen. If an enlarged parathyroid gland was seen, other parathyroid glands were examined, and all enlarged parathyroid glands were removed. In patients in the positive screening group, the surgeon looked for all four parathyroid glands. Parathyroid tumors found near the thyroid were rated easily accessible; all others were rated as requiring specific dissection.

The results of the study. Among the 748 patients, 87 (12 percent) had a high serum calcium value. Among them, 30 had a second high serum calcium value, of whom 9 (30 percent) had a high serum PTH value (positive screening group). At surgery, all 9 of these patients had a parathyroid adenoma, which was rated as easily accessible in 6 and as requiring specific dissection in 3. Among the patients in whom screening was negative, only 12 (2 percent) had one or more visibly enlarged parathyroid glands, which were removed. Overall, 23 patients (3 percent) had parathyroid tumors; 12 (2 percent) had incidental tumors discovered at surgery, 9 (1 percent) had tumors detected by screening, and 2 (0.3 percent) were later found to have tumors.

The conclusions of the study. Few patients scheduled for thyroid surgery have parathyroid adenomas, and not all can be suspected by studies before surgery.

The original article. Denizot A, Dadoun F, Meyer-Dutour A, Alliot P, Argeme M. Screening for primary hyperparathyroidism before thyroid surgery: a prospective study. Surgery 2002;131:264-9.