Insulin resistance is associated with Fibroblast Growth Factor-23 in stage 3-5 chronic kidney disease patients

Aim: To determine the associations between insulin resistance, fibroblast growth factor 23 (FGF-23), and coronary artery calcification (CAC) in chronic kidney disease (CKD) patients. Introduction: FGF-23 is associated with atherosclerosis and cardiovascular disease, but its association with insulin resistance in CKD has not been explored. Subjects: Cross sectional study of 72 stage 3-5 CKD patients receiving care in Ontario, Canada. Materials and Methods: Insulin resistance was measured by the homeostasis model assessment of insulin resistance (HOMA-IR), FGF-23 was measured by carboxyl terminal enzyme linked immunoassay (ctFGF-23) and CAC was measured by multi-slice computed tomography. Results: Median HOMA-IR was 2.19 mu U/ml (interquartile range 1.19 to 3.94). Patients with HOMA-IR > 2.2 had greater ctFGF-23 (179.7 vs 109.6; P = 0.03), and 40% higher log CAC scores (2.09 +/- 0.87 vs 1.58 +/- 1.26; P = 0.049). Multivariable linear regression adjusted for 1,25 dihydroxyvitamin D, kidney function, and parathyroid hormone revealed insulin resistance was a risk factor for greater log ctFGF-23 levels (log HOMA IR beta = 0.37; 95% confidence interval 0.14 to 0.59; P = 0.002). Conclusions: Insulin resistant CKD patients demonstrated higher FGF-23 levels, and increased CAC, while PO4 levels remained normal, suggesting a potential link between insulin resistance and PO4 homeostasis in CKD. (C) 2014 Elsevier Inc. All rights reserved.