Prospective study in 3,000 consecutive parathyroid operations demonstrates 18 objective factors that influence the decision for unilateral versus bilateral surgical approach.

BACKGROUND: Although localizing studies are well-known predictors of which patients are candidates for unilateral versus bilateral parathyroid exploration, there are a number of other factors that have positive or negative influence preoperatively and intraoperatively.

STUDY DESIGN: A prospective study was conducted during 20 months on 3,000 consecutive patients undergoing surgery for primary hyperparathyroidism to determine which factors caused the surgeons to explore bilaterally or, in contrast, influenced a unilateral approach. Seventeen preoperative and 5 intraoperative objective points were documented on all patients to see how decisions were made.

RESULTS: Parathyroidectomy was unilateral in 32% and bilateral in 68%. Preoperative factors that had a positive predictive value in dictating a unilateral approach were (in decreasing frequency): positive sestamibi, previous parathyroid/thyroid surgery, age older than 80 years, anticoagulation medications, morbid obesity, and presence of large goiter (all p < 0.001). Preoperative parameters dictating a bilateral approach included negative sestamibi, more than one focus on sestamibi, contralateral thyroid disease, family history, lithium use, history of radiation, MEN, age younger than 20 years, and pregnancy (all p < 0.001). Intraoperative parameters influencing conversion of unilateral to bilateral were false-positive sestamibi, hormone measures not meeting sufficient levels, abnormal ipsilateral gland, and contralateral thyroid pathology identified (all p < 0.001). Factors that had no effect were gender, degree of calcium, and/or parathyroid hormone elevation, and age between 20 and 80 years. Cure rates were 99.9% for bilateral and 99.0% for unilateral (p = 0.057).

CONCLUSIONS: High-volume surgeons use a number of identifiable objective factors to determine the best candidates for unilateral versus bilateral parathyroid exploration. Localizing studies such as sestamibi scans ultimately play a minor role in determining how many parathyroid glands are evaluated.