Is preoperative investigation of the thyroid justified in patients undergoing parathyroidectomy for hyperparathyroidism?

Background: The finding of coexisting nodular thyroid disease during neck exploration for hyperparathyroidism (HPT) is reported to range from 20%-60%. Thus, the surgeon may encounter a second, unrelated lesion during open parathyroidectomy. Furthermore, with the recent introduction of minimally invasive surgery for HPT, the entire neck may not be explored, and it is important to know the potential risk of missing significant, concurrent thyroid disease. The diagnosis and timely treatment of associated thyroid abnormalities is desirable because a delay in operating would result in increased morbidity associated with a second neck exploration. Design: We examined our 25-year experience at a large tertiary academic medical center, to determine the incidence and type of concurrent thyroid disease seen in patients with HPT. The computerized records of the Department of Pathology, from 1974-1999, were reviewed for patients with primary HPT who underwent surgery. Results: A review of records from 580 patients who underwent surgery for primary HPT showed 103 (18%) patients with concomitant thyroid disease at surgery. All 103 underwent thyroid resection at the time of parathyroidectomy. Thyroid histology showed: 12 (12%): well-differentiated papillary carcinomas, 31 (30%): follicular adenomas, 49 (48%): nodular hyperplasias, 8 (8%): chronic lymphocytic thyroiditis, 1 benign cyst, 1 metastasis, and 1 normal. Conclusions: Synchronous thyroid disease was found in 18% of primary HPT patients undergoing surgery, and 12% of thyroid lesions were malignant. The overall malignancy rate was 2%. All primary malignancies found were papillary carcinomas, of which 7 of 12 (58%) were microcarcinomas. The significant association of simultaneous pathology in the two glands justifies preoperative thyroid imaging and fine-needle aspiration (FNA) biopsy to determine the best surgical approach for patients with HPT.