Table 1.

Baseline characteristics by FGF23 and FePi above and below the median

VariableLow FGF23High FGF23P ValueLow FePiHigh FePiP Value
Number437435436436
Range (RU/ml for FGF23, % for FePi)<42.3≥42.3<15.7≥15.7
Age (yr)±SD67±1167±110.7765±1169±11<0.001
Sex n (%)<0.01<0.001
 Male374 (86)341 (78)330 (76)385 (88)
 Female63 (14)94 (22)106 (24)51 (12)
Estrogen use (women) n (%)24 (38)17 (18)<0.0129 (27)12 (24)0.61
Race n (%)0.04<0.001
 White253 (58)278 (64)236 (54)295 (68)
 Black63 (14)68 (16)89 (20)42 (10)
 Other121 (28)89 (20)111 (25)99 (23)
Diabetes n (%)105 (24)122 (28)0.18121 (28)106 (24)0.25
Systolic BP (mmHg)±SD132±21134±210.18133±21133±210.88
BMI (kg/m2)±SD28.1±4.628.8±6.00.0528.7±5.528.1±5.20.07
Smoking n (%)67 (15)97 (22)<0.0196 (22)68 (16)0.02
Total cholesterol (mg/dl)±SD175±39180±460.07179±43176±420.20
HDL cholesterol (mg/dl)±SD46±1345±150.1946±1445±140.23
CRP (mg/dl) median (IQR)1.8 (0.7–3.5)2.8 (1.1–6.3)<0.0012.3 (0.9–4.6)2.1 (0.9–4.8)0.95
eGFR (ml/min per 1.73 m2)±SD77±1965±24<0.00177±2365±20<0.001
ACR (mg/g) median (IQR)8.0 (4.6–14.6)10.5 (5.7–23.5)<0.0018.4 (4.9–16.6)9.3 (5.3–20.8)0.22
PTH (pg/ml) median (IQR)50 (40–65)56 (40–79)<0.0150 (39–65)56 (42–74)<0.001
Serum phosphorus (mg/dl)±SD3.6±0.53.8±0.6<0.0013.8±0.53.5±0.6<0.001
Serum calcium (mg/dl)±SD9.5±0.59.5±0.50.189.6±0.59.5±0.50.01
Urine phosphorus (mg/dl)±SD47±2546±250.5037±2156±26<0.001
FePi (%)±SD16±719±10<0.001
FGF23 (RU/ml) median (IQR)40 (26–60)47 (30–80)<0.001