Objective: The effects of normocalcemic hyperparathyroidism (NHPT) on bone remain unclear. The objective of this study was to evaluate differences in the trabecular bone score (TBS) of NHPT patients and asymptomatic hypercalcemic hyperparathyroidism (HHPT) patients.
Methods: We performed a prospective study that enrolled consecutive patients with asymptomatic hyperparathyroidism (NHPT and HHPT) with a follow-up ≥1 year at the University Hospital of Valladolid, Spain. Metabolic phosphocalcium plasma and urine parameters were evaluated in ≥2 determinations during follow-up to classify patients as NHPT patients or asymptomatic HHPT patients. A control group was enrolled during the same period. TBS and bone mineral density (BMD) were evaluated.
Results: Thirty-nine patients with asymptomatic HPT (24 with NHPT and 15 with HHPT) and 24 controls were recruited. NHPT patients and HHPT patients had a similar mean age, vitamin D level, TBS, and areal BMD (all sites). Compared to controls, symptomatic HPT patients had significantly higher parathyroid hormone (PTH) and calcium levels and significantly lower TBS and areal BMD at all sites (all P<.05). A significant negative relationship between TBS and PTH was found in asymptomatic HPT patients (r = -0.320, P = .043), which remained significant after adjustment for age, sex, and body mass index.
Conclusion: There was no difference in the TBS between NHPT and HHPT patients. However, there was a reduction in the TBS of patients with asymptomatic HPT that was related to PTH levels but had no repercussion on bone mass. Higher levels of PTH seem to be responsible for this alteration in microarchitecture texture.
Abbreviations: aBMD = areal bone mineral density BMD = bone mineral density BMI = body mass index DXA = dual-energy X-ray absorptiometry HHPT = hypercalcemic hyperparathyroidism HPT = hyperparathyroidism HR-MRI = high-resolution magnetic resonance HR-pQcT = high-resolution peripheral quantitative computed tomography NHPT = normocalcemic hyper-parathyroidism PTH = parathyroid hormone TBS = trabecular bone score 25vitD = 25-hydroxyvitamin D.