Table 5.
Association between urinary sodium and calcium excretion and incident kidney stones
| HPFS | NHS I | NHS II | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Urinary Sodium Excretion (mEq/day) | Mean Adjusted Urinary Calcium Excretion (mg/day) | RR | (95% CI) | Mean Adjusted Urinary Calcium Excretion (mg/day) | RR | (95% CI) | Mean Adjusted Urinary Calcium Excretion (mg/day) | RR | (95% CI) |
| <120 | 178 | 1.00 | (reference) | 161 | 1.00 | (reference) | 189 | 1.00 | (reference) |
| 120–139 | 186 | 1.10 | (0.68, 1.77) | 179 | 1.33 | (0.91, 1.93) | 206 | 0.93 | (0.63, 1.39) |
| 140–159 | 192 | 0.90 | (0.56, 1.43) | 174 | 1.37 | (0.91, 2.07) | 196 | 1.10 | (0.74, 1.64) |
| 160–179 | 201 | 1.10 | (0.68, 1.77) | 193 | 1.44 | (0.90, 2.29) | 214 | 1.17 | (0.75, 1.84) |
| 180–199 | 205 | 1.49 | (0.88, 2.50) | 188 | 1.05 | (0.64, 1.71) | 206 | 0.94 | (0.54, 1.63) |
| 200–219 | 203 | 1.61 | (0.93, 2.81) | 170 | 0.93 | (0.51, 1.69) | 234 | 1.14 | (0.64, 2.01) |
| 220+ | 228 | 2.06 | (1.27, 3.32) | 208 | 1.79 | (1.05, 3.04) | 229 | 1.01 | (0.63, 1.63) |
Risk adjusted for age, history of hypertension, body mass index and urinary factors—total volume, creatinine, oxalate, uric acid, citrate, magnesium, potassium, phosphosphorus and pH.
HPFS: Health Professionals Follow-up Study—728 cases and 417 controls (total 1145).
NHS I: Nurses’ Health Study I—947 cases and 407 controls (total 1354).
NHS II: Nurses’ Health Study II—833 cases and 443 controls (1276).