Unknown and already known thyroid abnormalities in primary hyperparathyroidism

Objective: Primary hyperparathyroidism (PHPT) and thyroid diseases are highly prevalent in the general population, but the putative link between the 2 conditions remains unclear. Methods: A monocentric consecutive series of 434 patients with PHPT was retrospectively evaluated by lab and ultrasonography to look for thyroid abnormalities. Patients were classified in 3 groups: without thyroid abnormalities (group 1, n = 171), with thyroid diseases not previously known (group 2a, n = 69), and thyroid diseases previously known (group 2b, n = 194). Results: In terms of thyroid disease, no significant difference was found between groups 2a and 2b, except for the significantly larger number of patients with toxic nodular goiter in group 2b. PHPT was more frequently symptomatic in group 2a than in group 2b, despite no differences in serum calcium, creatinine, parathyroid hormone (PTH), or 25-hydroxyvitamin D (25OHD) levels. Conclusion: A total of 60% of PHPT patients had a thyroid disease that was unknown prior to PHPT diagnosis in almost one-third of cases. The newly diagnosed and previously known thyroid diseases were similar, both mostly affecting postmenopausal females.