High fibroblast growth factor 23 is associated with coronary calcification in patients with high adiponectin: analysis from the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD) study

Background. The association between fibroblast growth factor 23 (FGF23) and coronary artery calcification (CAC) was inconclusive. Recently it was shown that adiponectin modulates renal handling of calcium and phosphorus. We hypothesized that adiponectin plays a role in the effect of FGF23 on CAC and explored whether the association between FGF23 and CAC is modified by serum adiponectin level in chronic kidney disease (CKD) patients. Methods. This cross-sectional study analyzed 1435 predialysis CKD patients from the Korean Cohort Study for Outcome in Patients with CKD cohort. Participants were divided into two groups according to their serum adiponectin (upper half and lower half). Each group was further divided into three groups according to their FGF23 levels as follows: low (<5.0 RU/mL), middle (5.0-29.9 RU/mL) and high (>= 30.0 RU/mL). The coronary artery calcium score (CACS) was assessed using cardiac computed tomography and CAC was defined as a CACS>100. Results. The median CACS did not differ between the low and high adiponectin groups {3.2 [interquartile range (IQR) 0.0-98.1] versus 0.5 [0.0-99.5], P = 0.988}. The CACS ratio comparing high FGF23 to low FGF23 was significantly increased in the high adiponectin group, but not in the low adiponectin group [2.35 (IQR 1.14-4.85) versus 1.10 (0.60-2.03)]. The odds ratio for CAC in the high FGF23 group compared with the low group was 1.97 (IQR 1.10-3.53). The association between FGF23 and CAC was modified significantly by adiponectin level (P for interaction = 0.023). Conclusions. High serum FGF23 was associated with CAC in CKD patients with high adiponectin, but not in those with low adiponectin. Further studies are warranted to verify the role of adiponectin in FGF23-related CAC.