Correlations between plasma strontium concentration, components of calcium and phosphate metabolism and renal...

Renal function decline in diabetic kidney disease is accompanied by calcium and phosphate metabolism alterations. Whereas strontium (Sr²⁺ ) has many similarities with calcium, little is known about Sr²⁺ in this respect. We studied the association of plasma Sr²⁺ concentration and parameters associated with an altered calcium and phosphate metabolism in diabetic kidney disease.

Plasma Sr²⁺ concentration was measured in 450 patients included in the DIAbetes 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 Sr²⁺ concentration and parameters of calcium and phosphate metabolism were studied using multivariate linear regression analysis.

Overall, median plasma Sr²⁺ 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 Sr²⁺ concentration and both eGFR (β = -0.401, P < 0.001) and plasma fibroblast growth factor 23 (FGF23) concentration (β = 0.087, P = 0.04).

We found an independent inverse association between eGFR and plasma Sr²⁺ concentration and an independent association between plasma Sr²⁺ concentration and plasma FGF23 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 Sr²⁺ concentration on bone mineralization and calcification.