Table 1.

Baseline characteristics by 24-hour urine phosphorus excretion tertiles

VariableUPE Tertile 1 (<508 mg/d)UPE Tertile 2 (508–748 mg/d)UPE Tertile 3 (>748 mg/d)P Value
Participants (n)294293293
Age (yr)69±1168±1063±11<0.001
Women73 (25)51 (17)34 (12)<0.001
Estrogen use in women19 (26)13 (26)9 (27)0.99
Race<0.001
 White156 (53)181 (62)200 (68)
 Black65 (22)43 (15)26 (9)
 Other73 (25)69 (24)67 (23)
Diabetes mellitus78 (27)70 (24)80 (27)0.61
Hypertension215 (73)209 (71)203 (69)0.59
Smoking61 (21)51 (17)54 (18)0.57
Body mass index (kg/m2)27.4±5.328.1±4.729.8±5.9<0.001
eGFR (ml/min per 1.73 m2)66±2672±2176±19<0.001
Urine albumin-to-creatinine ratio (mg/g)a11 (7, 23)8 (5, 17)7 (4, 14)<0.001
Diuretic use108 (37)80 (27)76 (26)<0.01
Vitamin use55 (19)62 (21)57 (19)0.75
Serum phosphorus (mg/dl)3.66±0.583.66±0.563.66±0.560.75
Serum calcium (mg/dl)9.50±0.529.55±0.549.52±0.480.10
PTH (pg/ml)a57 (41, 77)52 (41, 69)50 (40, 66)<0.01
FGF-23 (RU/ml)a46 (30, 86)40 (26, 64)43 (28, 68)0.09
Urine calcium (mg/d)a38 (19, 68)74 (46, 125)137 (71, 205)<0.001
  • Data are presented as mean ± SD or number (percentage) of participants unless otherwise indicated. P values represent chi-squared tests or ANOVA. UPE, urinary phosphorus excretion; eGFR, estimated GFR; PTH, parathyroid hormone; FGF-23, fibroblast growth factor-23.

  • a Median (interquartile range).