mRNA expression of vitamin D receptor, calcium-sensing receptor, cyclin D1, and PTH in symptomatic and asymptomatic primary hyperparathyroidism.

Background and objective: The exact underlying mechanism for the differential clinical profiles of symptomatic and asymptomatic primary hyperparathyroidism (PHPT) patients has not been fully elucidated, and efforts to define the molecular mechanisms underlying the phenotypic heterogeneity of PHPT have been limited. The aim of this study was to explore the underlying molecular mechanisms involved in the pathogenesis of symptomatic and asymptomatic sporadic PHPT in Asian Indians.

Methods: A prospective cohort study was conducted at a tertiary care hospital in North India. PHPT patients who underwent parathyroidectomy were included. The main outcome was the comparison of vitamin D receptor (VDR), calcium-sensing receptor (CaSR), cyclin D 1 (CD1), and parathyroid hormone (PTH) mRNA levels between symptomatic and asymptomatic PHPT patients and controls determined via quantitative real-time polymerase chain reaction (qRT-PCR).

Results: Forty-two PHPT patients were studied. The mean (SD) age was 49.7 (12.8) years. Twenty patients were asymptomatic. The median PTH levels were significantly greater in the symptomatic group than in the asymptomatic group (878 vs 653 pg/mL). CaSR and VDR mRNAs were significantly lower in both symptomatic and asymptomatic patients than in controls. CD1 and PTH mRNAs were significantly increased in symptomatic patients, but not in asymptomatic PHPT patients compared with controls. Symptomatic PHPT patients had significantly greater CD1 mRNA expression and reduced CaSR expression than asymptomatic patients.

Conclusion: Symptomatic PHPT patients had significantly greater CD1 mRNA expression and lower CaSR expression than asymptomatic patients, underscoring the importance of the molecular mechanisms underlying the phenotypic heterogeneity of PHPT.