Mineral metabolism and inflammation in chronic kidney disease patients: a cross-sectional study.

Background and Objectives: Mineral metabolism abnormalities and inflammation are concerns in chronic kidney disease (CKD). Interrelationships among these parameters have not been analyzed.
Design, Setting, Participants, and Measurements: The study included 133 patients with CKD not on dialysis and not receiving calcium (Ca) supplements, phosphate binders, or vitamin D. Estimated GFR (eGFR) was 34.1 +/- 6.8 ml/min/1.73 m(2); 107 participants had stage 3 CKD, and 26 had stage 4.
Results: Patients were classified by tertiles of Ca, phosphorus (P), Ca-P product (Ca x P), and parathyroid hormone (PTH). After adjustment for age, gender, and eGFR, the levels of C-reactive protein (CRP) and IL-6 (IL-6) of the third tertile of P, Ca x P, and PTH were significantly higher than those of the first and second tertiles. Serum P and Ca x P directly correlated with CRP and IL-6, whereas HDL-cholesterol and eGFR inversely correlated with the levels of the inflammatory parameters. After partial correlation analysis, the previous associations between CRP and eGFR, and serum P, as well as the relationship between IL-6 and eGFR, and serum P, remained significant. Multiple regression analysis demonstrated that eGFR and serum P were independently associated with CRP and IL-6. Finally, logistic regression analysis using the presence/absence of an inflammatory state as the dependent variable showed that eGFR was a protective factor, whereas serum P was an independent risk factor for the presence of an inflammatory state.
Conclusions: Elevated serum P might play a role in the development of inflammation in CKD.