RADIOLOGIC MANIFESTATION of BONE INVOLVEMENT in PRIMARY HYPERPARATHYROIDISM: PREVALENCE and CLINICAL SIGNIFICANCE in A SOUTHERN EUROPEAN SERIES

Objective: Clinically overt symptomatic bone disease in primary hyperparathyroidism (PHPT) is rarely seen today, and osteoporosis is the dominant finding. Subperiosteal bone resorption in the fingers and skull mottling are typical bone PHPT findings, the contemporary prevalence of which is unknown. We evaluated these mild lesions and investigated the impact of their occurrence on PHPT clinical management. Methods: We evaluated retrospectively a monocentric series of 363 PHPT patients classified in Group 1 (n = 100) or Group 2 (n = 263) according to the presence or absence of bone involvement, respectively. Patients belonging to Group 1, in turn, were subdivided into Group 1A, with severe and symptomatic lesions (n = 48), and Group 1B, with milder signs of osteitis fibrosa cystica (OFC) without brown tumors or fractures (n = 52). Results: Serum total and ionized calcium, parathyroid hormone, osteocalcin, alkaline phosphatase, and its bone fraction levels were higher in Group 1 than in Group 2, while no gender or age differences were observed between the groups. Osteoporosis prevalence was similar in Group 1B and Group 2 patients but lower than in Group 1A. Mild OFC findings did not modify the surgical indication in any patient of Group 1B. Conclusion: Minor radiologic signs of OFC are not uncommon in the modern PHPT phenotype and occur in patients with more active disease. These signs could identify PHPT patients in an earlier stage of typical bone involvement. However, these features do not seem to upgrade either the clinical classification of asymptomatic PHPT patients or the propensity toward surgical choice. Abbreviations: 25OHD = 25-hydroxyvitamin D; ALP = alkaline phosphatase; bALP = bone-specific alkaline phosphatase; BMD = bone mineral density; eGFR = estimated glomerular filtration rate; OFC = osteitis fibrosa cystica; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; VF = vertebral fracture