Table 3.
First available serum and urine laboratory characteristics after the first stone episode by different stone compositions.
| Laboratory characteristic a mean (SD) or % |
Known Composition | Composition | Calcium Oxalate | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No (n=1453) |
Yes (n=1488) |
P-value b | Calcium Oxalate (n=1127) |
Hydroxy apatite (n=264) |
Brushite (n=13) |
Struvite (n=13) |
Uric Acid (n=71) |
P-valueb | Dihydrate (n=173) |
Mono hydrate (n=954) |
P-value b | |
| Serum calcium, mg/dl | 9.4 (0.55) |
9.4 (0.63) |
.24 | 9.5 (0.63) |
9.4 (0.63) |
9.6 (0.42) |
9.2 (0.87) |
9.4 (0.58) |
.14 | 9.6 (0.56) |
9.4 (0.63) |
.007 |
| Serum phosphorus, mg/dl | 3.3 (0.73) |
3.3 (0.68) |
.83 | 3.3 (0.67) |
3.4 (0.71) |
3.1 (0.82) |
2.9 (0.98) |
3.6 (0.69) |
.008 | 3.2 (0.84) |
3.3 (0.63) |
.64 |
| Serum uric acid, mg/dl | 5.7 (1.6) |
5.5 (1.6) |
.005 | 5.6 (1.5) |
4.8 (1.4) |
4.8 (1.6) |
4.9 (1.8) |
6.8 (2.0) |
<.001 | 5.3 (1.3) |
5.6 (1.5) |
.29 |
| Serum bicarbonate, mmol/l | 26 (2.8) |
26 (2.7) |
.12 | 26 (2.7) |
25 (2.9) |
25 (2.1) |
26 (1.6) |
25 (2.7) |
.008 | 26 (2.7) |
26 (2.7) |
.41 |
| Urine calcium, mg/24 hr | 225 (126) |
219 (131) |
.29 | 220 (129) |
224 (131) |
N/A‡ | N/A | 152 (91) |
.02 | 253 (148) |
214 (124) |
.03 |
| Urine citrate, mg/24 hr | 621 (286) |
631 (289) |
.71 | 640 (277) |
570 (245) |
N/A | N/A | 661 (364) |
.09 | 611 (199) |
645 (289) |
.60 |
| Urine oxalate, mmol/24 hr | 0.32 (0.15) |
0.34 (0.18) |
.04 | 0.36 (0.20) |
0.28 (0.11) |
N/A | N/A | 0.32 (0.14) |
<.001 | 0.34 (0.16) |
0.37 (0.20) |
.24 |
| Urine phosphorus, mg/24hr | 938 (360) |
932 (362) |
.73 | 938 (368) |
883 (338) |
N/A | N/A | 955 (314) |
.35 | 886 (407) |
948 (359) |
.12 |
| Urine uric acid, mg/24 hr | 602 (232) |
599 (220) |
.82 | 616 (224) |
523 (168) |
N/A | N/A | 635 (271) |
.01 | 595 (173) |
619 (232) |
.75 |
| Urine sodium, mmol/24 hr | 140 (2.5) |
147 (41) |
.18 | 148 (44) |
144 (29) |
N/A | N/A | 145 (40) |
.91 | 151 (51) |
148 (43) |
.94 |
| Urine volume, ml/24 hr | 1671 (849) |
1730 (832) |
.18 | 1752 (805) |
1644 (899) |
N/A | N/A | 1763 (1032) |
.25 | 1659 (725) |
1769 (819) |
.39 |
| Urine pH | 6.0 (0.78) |
6.0 (0.77) |
.32 | 6.0 (0.75) |
6.3 (0.79) |
N/A | N/A | 5.5 (0.70) |
<.001 | 6.1 (0.66) |
5.9 (0.76) |
.01 |
| Microhematuria, % | 90 | 89 | .23 | 88 | 89 | 100 | 100 | 93 | .41 | 90 | 88 | .46 |
a
Laboratories were available in a subset for serum calcium (75%), phosphorus (65%), uric acid (61%), and bicarbonate (41%); for urine calcium (37%), citrate (34%), oxalate (44%), phosphorus (30%), uric acid (29%), sodium (49%), volume (39%), and pH (83%); and microhematuria (85%).
b
Unadjusted associations; Kruskal-wallis, Wilcoxon and T-tests were used to calculate p-values for continuous variables; chi-squared tests were used to calculate p-values for categorical variables.
N/A: Not available as number of subjects too few for analysis