Endocrine Abstracts

Objective: Primary hyperparathyroidism (PHPT) and thyroid diseases are common in the general population. It is difficult to establish whether they occur in the same patient because of a direct relationship or just due to the widespread prevalence of both conditions. The reported prevalence of the concomitant occurrence of these two clinical conditions is widely scattered (ranging 17–84%), especially due to the heterogeneous criteria for patient selection. We aimed to evaluate in a large series of PHPT patients the prevalence of thyroid diseases and the clinical and biochemical presentation of PHPT in patients without or with concomitant thyroid diseases.

Methods: We retrospectively evaluated an unselected and monocentric series of 434 outpatients with PHPT, attending our hospital between 1998 and September 2017. Patients with neither bone or kidney involvement, nor hypercalcemic symptoms were considered asymptomatic. The US thyroid pattern was considered abnormal if nodules or features of chronic lymphocytic thyroiditis were found. The histological report of patients submitted to thyroidectomy was then evaluated.

Results or Case Presentation: Thyroid diseases were found in 263/434 (60.6%) PHPT patients. Among them, over than 80% were affected by nodular goiter, that was toxic in almost 10% of cases. Thyroid autoantibodies were positive in 50 (19%) patients, all with an autoimmune US pattern. Thyroid cancer was diagnosed in 11/85 patients (12.9%) and it was a papillary microcarcinoma in all cases but one. Patients with thyroid diseases were older and more frequently female than the others, despite no difference in serum calcium, creatinine, 25OHD and TSH levels. PTH levels result significantly higher in patients without thyroid abnormalities. Anyway, no difference were found in the PHPT clinical presentation nor in the presence of osteoporosis at any site between the two groups.

Discussion: Thyroid diseases, mostly nodules, were present in 60% of our patients with PHPT,consistently with the goiter endemic area where our study has been conducted. Moreover, a thyroid carcinoma was found in more than 10% of patients. The predominantly histotype was papillary microcarcinoma, in agreement with literature data. PHPT characteristics resulted biochemically and clinically similar in patients with or without thyroid abnormalities.

Conclusion: In conclusion, the majority of PHPT patients have a thyroid disease. Our data confirm that thyroid diseases and PHPT are two conditions prevailing in specific population, thus making their association more frequent. Thyroid nodules could interfere in the diagnostic and therapeutic PHPT work up.