Table 3.

Multivariate-adjusted differences in 24-h urinary oxalate excretion by category of dietary or urinary factora

Difference in Urinary Oxalate (mg/d)95% CIP for Trend
Dietary oxalate
    quartile 1Referent
    quartile 21.2(0.3 to 2.1)
    quartile 31.3(0.4 to 2.2)
    quartile 41.7(0.8 to 2.6)
0.001
Dietary calcium
    quartile 1Referent
    quartile 2−1.4(−2.4 to −0.5)
    quartile 3−2.1(−3.0 to −1.2)
    quartile 4−2.3(−3.2 to −1.3)
<0.001
Supplemental calcium
    NoneReferent
    1 to 100 mg/d−0.3(−1.6 to 1.1)
    101 to 500 mg/d−1.0(−1.8 to −0.1)
    >500 mg/d−1.7(−2.7 to −0.8)
<0.001
Total vitamin C
    <90 mg/dReferent
    90 to 249 mg/d2.1(1.0 to 3.2)
    250 to 499 mg/d3.5(2.2 to 4.9)
    500 to 999 mg/d3.6(2.2 to 5.0)
    ≥1000 mg/d6.8(5.2 to 8.3)
<0.001
Urinary potassium
    quartile 1Referent
    quartile 21.3(0.3 to 2.2)
    quartile 32.6(1.6 to 3.6)
    quartile 44.3(3.2 to 5.4)
<0.001
Urinary magnesium
    quartile 1Referent
    quartile 20.7(−0.2 to 1.6)
    quartile 31.5(0.5 to 2.4)
    quartile 43.4(2.4 to 4.4)
<0.001
Urinary phosphorus
    quartile 1Referent
    quartile 22.1(1.1 to 3.0)
    quartile 31.7(0.7 to 2.7)
    quartile 43.6(2.5 to 4.8)
Urinary creatinine<0.001
    quartile 1Referent
    quartile 21.2(0.2 to 2.2)
    quartile 32.3(1.3 to 3.4)
    quartile 43.8(2.6 to 5.0)
<0.001
  • a Adjusted for age, kidney stone history, cohort, weight (continuous), 24-h urinary excretion of creatinine, potassium, magnesium, and phosphorus (all in quartiles), dietary oxalate and calcium (quartiles), total intake of vitamin C (five categories), and supplemental calcium intake (four categories).