Background: The normocalcaemic hyperparathyroidism (NHPT) has been defined as a condition with persistently normal total and ionized calcium levels in the presence of high levels of PTH. The clinical aspects of NHPT have been evaluated in different cohorts but the interpretation of these findings is confounded by differing methods used to rule out secondary hyperparathyroidism and by the small number of NHPT subjects enrolled. Up to now, there is no information available that could determine the optimal management of this condition.
Objective: To evaluate the clinical, biochemical and radiological profile of NHPT in comparison with PHPT and control subjects.
Methods: We designed a multicentric cross-sectional study and we enrolled patients with NHPT and primary hyperparathyroidism (PHPT) diagnosed according to criteria of the Fourth International Workshop of Asymptomatic Hyperparathyroidism. Body mass index (BMI) and age matched control subjects were consecutively recruited from outpatient clinic of endocrinology at Campus Bio-Medico. All patients underwent a biochemical examination including calcium-phosphorus metabolism and bone turnover markers. We evaluated the lumbar spine (L1L4), total hip, femoral neck, and non-dominant forearm bone mineral density (BMD) and the trabecular bone score (TBS). Morphometric vertebral fracture (VF) were assessed by DXA scan.
Results: From December 2016 to July 2018, we identified 47 patients with NHPT, 41 with PHPT and 39 control subjects. All study groups had no significant differences in terms of age, BMI and kidney function. NHPT and PHPT patients had significantly higher PTH and 25(OH) Vitamin D levels (P<0.001) and lower Ca*P (P<0.001) compared to controls. NHPT has lower CTX levels compared to PHPT (P=0.039) and no differences were recorded compared to controls. In NHPT group, P1NP resulted not different when compared to controls and PHPT subjects. Compared to controls, NHPT (P=0.035) and PHPT (P=0.003) group have lower total hip BMD; NHPT showed higher non-dominant forearm BMD than PHPT subjects (P=0.017), while compared to controls presented similar values. No significant differences in TBS between the three groups have been founded. After adjustment for confounding factors, only PHPT group had an increased risk of VF compared to controls (OR:5.10, 95% CI:1.34 to 21.58). 31% of NHPT and 12% of PHPT patients fulfilled the criteria for asymptomatic hyperparathyroidism.
Conclusion: Up to now, our study described the biochemical and radiological profile of the largest cohort of NHPT subjects. Our findings suggest that the profile of NHPT subjects is closer to control one.
18 - 21 May 2019
European Society of Endocrinology