Parathyroidectomy Reduces Inflammatory Cytokines and Increases Vitamin D Metabolites in Patients With Primary Hyperparathyroidism

Objective

Primary hyperparathyroidism (PHPT) is accompanied by a decreased 25-hydroxyvitamin D (25OHD) and vitamin D binding protein (DBP). High parathyroid hormone (PTH) is associated with elevated interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), yet the effect of parathyroidectomy (PTX) on DBP and cytokines is not clear. This study aims to prospectively evaluate the effect of PTX on inflammatory profiles, total and free 25OHD, and DBP in patients with PHPT.

Methods

Newly diagnosed patients with PHPT were recruited for the study (n = 70). Twenty-eight patients returned after PTX, 3 months later. Biochemical markers were measured before and after PTX. A group of age and body mass index-matched healthy subjects were included as controls (n = 70).

Results

Before PTX, patients had lower serum DBP (37.5 ± 6.0 vs 41.5 ± 6.1 mg/dL, P < .001) and total 25OHD (30.1 ± 9.5 vs 33.3 ± 7.9 ng/mL, P < .05) but similar free 25OHD when compared to controls. Serum IL-6, C-reactive protein, and MCP-1 were higher in patients with PHPT (P < .05), whereas interleukin-10 was similar to that in controls. PTX increased total and free 25OHD and DBP (P < .001) and decreased serum IL-6 and MCP-1 (P < .05), but not C-reactive protein and interleukin-10. Multiple regression analysis indicated that the preoperative PTH explained a significant portion of the variance of IL-6 and MCP-1 (P < .05).

Conclusion

These findings suggest that PTH may upregulate the production of MCP-1 and IL-6 and downregulate circulating DBP in patients with PHPT that are normalized by PTX. The exact mechanism of IL-6 and MCP-1 on DBP, vitamin D metabolites, and clinical outcomes in patients with PHPT is an area requiring further study.