Table 1.
Clinical characteristics of study participants
| Nonstone Formers | Calcium Stone Formers | P Value | |
|---|---|---|---|
| Number of participants | 40 | 64 | |
| Age at urine collection, yr | 62.2 (13.1) | 62.7 (12.0) | 0.87 |
| Sex | |||
| Female | 20 (50.0%) | 31 (48.4%) | |
| Male | 20 (50.0%) | 33 (51.6%) | |
| Body mass index, kg/m2 | 26.8 (4.3) | 29.8 (6.6) | 0.02* |
| Systolic blood pressure, mmHg | 122.1 (16.5) | 126.6 (19.4) | 0.30 |
| Diastolic blood pressure, mmHg | 73.7 (9.3) | 70.4 (12.6) | 0.13 |
| Urine calcium, mg/24 h | 150.5 (85.2) | 231.1 (129.6) | <0.01* |
| Urine chloride, mmol/24 h | 121.8 (59.3) | 134.5 (81.0) | 0.65 |
| Urine citrate, mg/24 h | 685.2 (399.0) | 564.6 (344.8) | 0.15 |
| Urine creatinine, mg/24 h | 1,052.9 (498.0) | 1,363.4 (636.0) | 0.01* |
| Urine uric acid, mg/24 h | 452.3 (214.0) | 524.3 (231.3) | 0.11 |
| Urine osmolality, mosmol/kgH2O | 545.1 (227.0) | 405.0 (222.4) | 0.01* |
| Urine oxalate, mmol/24 h | 0.3 (0.1) | 0.3 (0.2) | 0.71 |
| Urine phosphate, mg/24 h | 656.7 (365.0) | 858.4 (459.0) | 0.01* |
| Urine potassium, mmol/24 h | 68.5 (50.1) | 59.0 (29.4) | 0.39 |
| Urine sodium, mmol/24 h | 130.5 (60.1) | 146.8 (91.4) | 0.61 |
| Urine sulfate, mmol/24 h | 18.3 (18.3) | 17.6 (8.8) | 0.54 |
| Urine pH | 6.4 (0.6) | 6.0 (0.6) | <0.01* |
| Urine volume, mL | 2,023.1 (608.0) | 2,080.5 (814.8) | 0.76 |
| Urine calcium phosphate (supersaturation), dG | −0.6 (1.1) | −0.4 (1.5) | 0.25 |
| Urine uric acid (supersaturation), dG | −2.9 (3.8) | 0.0 (2.7) | <0.01* |
| Urine calcium oxalate (supersaturation), dG | 1.1 (0.8) | 1.7 (0.7) | <0.01* |
Data are presented as means (SD). dG, ΔGibbs. Statistical differences between groups were determined by a Kruskal-Wallis test. P < 0.05 was considered statistically significant.
*
Statistical significance.