Table 2.

Adjusted mean concentrations of mineral metabolism measures by urine phosphorus excretion tertiles and β coefficients from linear regression

VariableUPE TertilesContinuous (per 300 mg/d Higher) UPE
Tertile 1
<508 mg/dTertile 2
508–748 mg/dTertile 3
>748 mg/dDifference in Variable (95% CI)P Value
Serum phosphorus (mg/dl)3.6 (3.6 to 3.7)3.7 (3.6 to 3.7)3.7 (3.6 to 3.7)0.034 (−0.002 to 0.072)0.07
Serum calcium (mg/dl)9.5 (9.4 to 9.6)9.6 (9.5 to 9.6)9.5 (9.5 to 9.6)−0.007 (−0.042 to 0.029)0.72
Ln-PTH (pg/ml)4.00 (3.95 to 4.05)3.97 (3.92 to 4.02)3.98 (3.93 to 4.02)−0.002 (−0.031 to 0.027)0.89
Ln-FGF-23 (RU/ml)3.8 (3.7 to 3.9)3.8 (3.7 to 3.9)3.9 (3.8 to 4.0)0.022 (−0.034 to 0.079)0.43
Urine calcium (mg/d)58. (51 to 66)90. (83 to 98)140. (132 to 147)37. (33 to 42)<0.001
  • Concentrations given as mean (95% confidence interval). Values are adjusted for age, sex, race, and estimated GFR. UPE, urinary phosphorus excretion; CI, confidence interval; LnPTH, natural logarithm parathyroid hormone; LnFGF-23, natural logarithm fibroblast growth factor-23.