Table 1.

Baseline characteristics according to serum phosphate concentrationa

CharacteristicSerum Phosphate Concentration (mg/dl)P
<3.0(n = 64)3.0 to 3.5(n = 157)3.6 to 4.0(n = 141)>4.0(n = 77)
Demographics
    age (mean [SD])68.7 (8.5)71.0 (8.8)69.5 (8.0)68.4 (8.1)0.0800
    race (n [%])
        white27 (42)66 (42)64 (45)32 (41)
        Chinese10 (16)22 (14)23 (16)12 (16)
        black16 (25)43 (27)28 (20)17 (22)
        Hispanic11 (17)26 (17)26 (18)16 (21)0.9600
    male gender (n [%])39 (61)71 (45)38 (27)17 (22)<0.0010b
Cardiovascular risk factors
    BMI (mean [SD])28.9 (5.5)28.3 (5.3)28.2 (5.2)29.7 (6.2)0.2100
    ever smoked (n [%])38 (60)62 (40)71 (51)33 (43)0.0600
    diabetes (n [%])
        none30 (47)87 (55)71 (50)32 (41)
        impaired fasting glucose20 (31)42 (27)39 (28)21 (27)
        diabetes14 (22)28 (18)31 (22)24 (31)0.3500
    SBP (mmHg; mean [SD])137 (27)134 (23)135 (22)134 (25)0.8900
    DBP (mmHg; mean [SD])76 (13)71 (10)70 (9)70 (12)0.0040
    LDL cholesterol (mg/dl; mean [SD])111 (32)116 (30)118 (35)125 (41)0.1000
    HDL cholesterol (mg/dl; mean [SD])50 (16)51 (15)52 (15)53 (16)0.7700
    triglycerides (mg/dl; mean [SD])161 (195)134 (63)151 (79)148 (71)0.2300
    C-reactive protein (mg/L; mean [SD])4.0 (4.6)4.1 (5.3)4.2 (5.7)5.1 (8.5)0.6100
    eGFR (ml/min per 1.73 m2; mean [SD])51.0 (6.4)50.8 (8.0)51.7 (7.7)47.7 (12.8)0.0100
    cystatin C (mg/L; mean [SD])1.17 (0.25)1.24 (0.36)1.21 (0.35)1.46 (0.86)<0.0010b
    microalbuminuria (n [%])13 (20)31 (20)35 (25)23 (30)0.2900
Mineral metabolism measurements
    phosphate (mg/dl; mean [SD])2.8 (0.2)3.3 (0.2)3.8 (0.1)4.4 (0.4)<0.0001b
    calcium (mg/dl; mean [SD])10.0 (0.4)10.1 (0.5)10.1 (0.4)10.3 (0.6)<0.0010b
    PTH (pg/ml; mean [SD])44 (27)37 (18)34 (29)37 (33)0.1400
    vitamin 25-D (ng/ml; mean [SD])23 (18)24 (15)24 (13)18 (12)0.0100
    vitamin 1,25-D (pg/ml; mean [SD])36 (14)36 (14)37 (15)32 (16)0.1100
    any calcium supplement (n [%])27 (42)71 (45)66 (47)38 (49)0.8800
Dietary intake measurements (mean [SD])
    calories (kcal/d)1614 (975)1388 (602)1430 (712)1555 (713)0.1400
    calcium (mg/d)920 (535)936 (684)1145 (963)1164 (749)0.0400
    phosphorus (mg/d)1068 (579)914 (452)951 (561)1061 (552)0.1200
    protein (g/d)63 (33)56 (26)56 (30)64 (30)0.1100
    fat (g/d)65 (45)52 (26)55 (31)60 (34)0.0400
  • a BMI, body mass index; DBP, diastolic BP; SBP, systolic BP.

  • b Statistically significant after Bonferroni correction for multiple comparisons (P < 0.002).