OBJECTIVEAcute kidney injury (AKI) was recently proposed for early recognition of renal function impairment and prompt interventions. Previous study revealed that AKI was highly associated with the prognosis. However, there was rare report of AKI in renal diseases, especially in children cohorts. Therefore, we performed the prospective clinical research in children with renal diseases in our hospital, aiming to study the prevalence, the clinical characteristics and the short-term prognosis of AKI.

METHODThe study was designed as a prospective, single-center observational study.

INCLUSION CRITERIA(1) the primary diagnosis was primary nephrotic syndrome (NS), Henoch-Schoenlein purpura nephritis (HSPN) or lupus nephritis (LN), (2) the duration from the onset of the renal diseases to the admission was less than 3 months. The serum creatinine and urine output of the subjects would be prospectively monitored. AKI was defined by the adult criteria and stratified by Acute Kidney Injury Network (AKIN) criteria. The patients were followed up at 6 months and 12 months after enrollment.

RESULTBetween October 2007 and April 2009, a total of 95 children were included, including 65 cases with NS, 15 HSPN and 15 LN. Mean age was (8.9 ± 3.9) years (range 2 - 16 years). Thirty-three of the 95 patients (34.7%) fulfilled the AKI criteria, 13 patients (13.7%) were diagnosed as acute renal failure (ARF). All the AKI in children with LN and HSPN presented with serum creatinine elevation. However, 65.4% of AKI in NS presented with decreasing urine output, only 19.2% accompanied with increasing creatinine, with higher stages of urine output. Regarding the etiology, only 26.9% of AKI in NS had definite cause, most of which resulted from side-effect of cyclosporine, hypovolemia or tubule-interstitial damage, independent of glomerular diseases. In contrast, the AKI in LN and HSPN were exclusively caused by glomerular diseases. The length and costs of hospitalization of AKI group were significantly higher than non-AKI [length of hospitalization (d), 28(6 to 94) vs. 21(7 to 100), Z = -1.971, P = 0.049; cost of hospitalization (yuan), 12 035.7 (1561.7 to 94 783.1) vs. 8594.3 (1390.1 to 98 876.5), Z = -1.993, P = 0.046]. There was no significant difference in the serum creatinine at 6-month and 12-month follow-up between AKI group and non-AKI [6-month, (60.4 ± 91.8) µmol/L vs. (42.8 ± 12.2) µmol/L, t = 0.937, P = 0.358; 12-month, (48.7 ± 18.1) µmol/L vs. (47.7 ± 14.2) µmol/L, t = 0.197, P = 0.845].

CONCLUSIONThe prevalence of AKI (34.7%) was higher than that of ARF (13.7%) in children with renal diseases. Most of the AKI in NS resulted from non-glomerular diseases. In contrast, most AKI in LN and HSPN were caused by underlying glomerular diseases. The length and costs of hospitalization were significantly higher in AKI group. However, there was no significant difference in serum creatinine between AKI and non-AKI group in the follow-up at 6 months and 12 months. Further investigations on criteria for the diagnosis of AKI in children with renal diseases are still needed.