Table 2.
Fractional clearances of solutes assayed using chemical standards
| Solute | Fractional Clearance | Free Fraction, % | |||||
|---|---|---|---|---|---|---|---|
| Control | CKD | CKD/Control | P Value | Control | CKD | P Value | |
| Urea N | 0.53±0.16 | 0.72±0.08 | 1.4 | ||||
| PAG | |||||||
| Total | 3.9±0.8 | 2.2±0.6 | 0.57 | <0.001 | 95±17 | 97±7 | 0.73 |
| Free | 4.2±0.6 | 2.3±0.6 | 0.56 | <0.001 | |||
| PCS | |||||||
| Total | 0.18±0.04 | 0.19±0.05 | 1.04 | 0.69 | 2.2±0.4 | 4.9±1.2 | <0.001 |
| Free | 8.6±2.6 | 4.1±1.5 | 0.47 | <0.001 | |||
| IS | |||||||
| Total | 0.53±0.11 | 0.40±0.14 | 0.76 | 0.007 | 2.4±0.7 | 5.7±1.7 | <0.001 |
| Free | 23.0±7.3 | 7.5±2.8 | 0.33 | <0.001 | |||
| HIPP | |||||||
| Total | 3.4±1.2 | 4.0±1.0 | 1.21 | 0.92 | 33±2 | 49±7 | <0.001 |
| Free | 10.2±3.8 | 8.4±2.6 | 0.82 | 0.13 | |||
Results are mean ± SD. The free fraction represents the proportion of solute that is not bound to protein and was calculated as the free level divided by the total level for each solute. CKD/control is the ratio of the average value in the participants with CKD to the average value in the control participants. PAG, phenylacetylglutamine; PCS, p-cresol sulfate; IS, indoxyl sulfate; HIPP, hippurate.