Prevalence of thyroid nodules and carcinomas in patients operated on for renal hyperparathyroidism: experience with 339 consecutive patients and review of the literature.

The association between renal hyperparathyroidism (HPT) and differentiated thyroid carcinoma is discussed. To determine the prevalence and potential risk factors, we performed a retrospective analysis of our patients (1998-2004) and compared the data with the data from other surgical and autopsy studies. At our hospital, a total of 347 parathyroidectomies in 339 patients with renal HPT were performed. Most patients underwent preoperative ultrasound investigation of the thyroid gland and, if indicate, thyroid scintigraphy. Intraoperatively, both thyroid lobes were mobilized and palpated. Detected thyroid nodules were adequately resected and investigated histologically. A systematic analysis of the international literature was performed using the PubMed/MEDLINE system to identify publications on the prevalence of papillary thyroid carcinoma (PTC) in patients with renal HPT and in the overall population. Altogether, 133 patients (39.2%) underwent simultaneous thyroid surgery. The initial operation was hemithyroidectomy in 55 (16.2%), Dunhill operation in 36 (10.6%), unilateral subtotal resection in 17 (5.0%), bilateral subtotal resection in 5 (1.5%), and enucleation of a thyroid nodule in 18 (5.3%). A PTC was found in 8 of 339 patients (2.4%) and a follicular thyroid carcinoma in 1. Among 311 patients with primary cervical operation, 6 (1.9%) had a papillary thyroid carcinoma. All papillary tumors were classified as pT1 with a diameter of 1 to 12 mm; three were bifocal, and only one patient had positive lymph nodes. None of the analyzed factors showed a significant correlation with the occurrence of thyroid carcinoma. Depending on the screening method, the prevalence of occult PTC in European autopsy studies ranged from 5% to 9% and was markedly higher in almost all studies than in the present one. The prevalence of PTC in the present study makes an etiologic association between renal HPT and PTC unlikely. The clinical significance of these tumors remains unclear because all incidental tumors were small. However, if easily and safely feasible, relevant thyroid nodules should be removed during parathyroid surgery.