Fibroblast growth factor-23 is a strong predictor of insulin resistance among chronic kidney disease patients

Insulin resistance (IR) is very common among chronic kidney disease (CKD) patients. Disturbance in mineral and bone metabolism (MBD) seems to play a role in the pathogenesis of insulin resistance. Fibroblast growth factor-23 (FGF23) is evolving as the most important link between MBD and many pathologic sequences of CKD. The aim was to evaluate IR in pre-dialysis CKD patients looking for a possible association to mineral metabolism among CKD patients. A total of 100 stage 3-5 CKD patients were selected beside 20 normal control subjects. Homeostatic model assessment of insulin resistance (HOMA-IR) was used to assess IR in selected cases. Both groups were compared for fasting blood glucose (FBG), fasting blood insulin (FBI), HOMA-IR, estimated glomerular filtration rate (eGFR), serum calcium (Ca), phosphorus (P), 25 hydroxy vitamin D (25 OH vit D), parathormone (PTH), and uric acid (UA). Correlation study between HOMA_IR and different studied parameters was performed. HOMA-IR is significantly higher in CKD (8.87 +/- 3.48 vs. 3.97 +/- 0.34 in CKD vs. control, respectively, p<.001). In addition CKD patients have significantly higher FGF23 (235 +/- 22.96 vs. 139 +/- 12.3pg/mL, p<.001), PTH (76.9 +/- 15.27 vs. 47.9 +/- 2.52pg/mL, p<.001), P (4.3 +/- 0.67 vs. 3.6 +/- 0.23mg/dL, p<.001), and UA (5 +/- 1.22 vs. 4.85 +/- 0.48mg/dL, p<.001) and significantly lower Ca (8.2 +/- 0.3 vs. 8.9 +/- 0.33mg/dL, p<.001), and 25 (OH) vit D (17 +/- 5.63 vs. 37 +/- 3.43ng/mL, p<.001). Stepwise linear regression analysis revealed that BMI, GFR, Ca, P, and FGF23 were the only significant predictors of HOMA IR. Increased IR in CKD is a consequence of the uremic status and is intimately associated with disturbed phosphate metabolism and FGF23. Further studies are needed to look for an underlying mechanism.