Evolution of protein-bound uremic toxins indoxyl sulphate and p-cresyl sulphate in acute kidney injury.

BACKGROUND

There is a gradual increase in serum concentrations of protein-bound colon-derived uremic toxins indoxyl sulphate (IxS) and p-cresyl sulphate (pCS) as chronic kidney disease (CKD) progresses. In acute kidney injury (AKI), up till now, the retention pattern has not been studied.

METHODS

In this study, 194 adult patients admitted with sepsis to the intensive care unit were included. IxS, pCS and serum creatinine (sCrea) were quantified at inclusion (D0) and at day 4, unless follow-up ended earlier (D).

RESULTS

Serum levels of sCrea (P < 0.001), IxS (P < 0.001) and pCS (P < 0.05) were higher in patients with AKI according to RIFLE classification at D0. In contrast with sCrea, IxS and pCS levels only increased from stage I (IxS) and F (pCS) on. When grouped according to evolution in RIFLE class from D0 to D, all solute concentrations were higher (P < 0.001) in the group with unfavourable evolution. In this group, there was a marked rise in sCrea (P < 0.001), a moderate one for pCS (P < 0.05), but no change for IxS (P = 0.112). There was a decrease (P < 0.001) of all solute concentrations in the group with favourable evolution. Comparing AKI with CKD patients matched for sCrea, total levels of both IxS and pCS were higher (P < 0.01) in patients with CKD.

CONCLUSIONS

Although concentrations of IxS and pCS both tend to rise in sepsis patients with AKI, their evolution does not conform with that of sCrea. For the same level of sCrea, IxS and pCS concentrations are lower in AKI compared with CKD.