Correlations between plasma strontium concentration, components of calcium and phosphate metabolism and renal function in type 2 diabetes mellitus

Background Renal function decline in diabetic kidney disease is accompanied by calcium and phosphate metabolism alterations. Whereas strontium (Sr 2+ ) has many similarities with calcium, little is known about Sr 2+ in this respect. We studied the association of plasma Sr 2+ concentration and parameters associated with an altered calcium and phosphate metabolism in diabetic kidney disease. Materials and methods Plasma Sr 2+ concentration was measured in 450 patients included in the DIA betes and LifEstyle Cohort Twente‐1. Patients were classified based on chronic kidney disease ( CKD ) stages: stages 1‐2, stage 3 and stages 4‐5 (estimated glomerular filtration rate of ≥60 mL·min −1 ·1.73 m −2 , 30‐59 mL·min −1 ·1.73 m −2 and ≤29 mL·min −1 ·1.73 m −2 , respectively). The associations between log‐transformed plasma Sr 2+ concentration and parameters of calcium and phosphate metabolism were studied using multivariate linear regression analysis. Results Overall, median plasma Sr 2+ concentration was in normal range, 269 nmol/L, but was progressively higher in patients with lower renal function, that is 246 nmol/L ( CKD 1‐2), 347 nmol/L ( CKD 3) and 419 nmol/L ( CKD 4‐5). In multivariate analysis, independent associations were found between plasma Sr 2+ concentration and both eGFR (β = −0.401, P  < 0.001) and plasma fibroblast growth factor 23 ( FGF 23) concentration (β = 0.087, P  = 0.04). Conclusions We found an independent inverse association between eGFR and plasma Sr 2+ concentration and an independent association between plasma Sr 2+ concentration and plasma FGF 23 concentration, a marker of deranged calcium and phosphate metabolism. Further research is needed to determine the mechanisms behind these associations and the impact of an elevation in plasma Sr 2+ concentration on bone mineralization and calcification.