[Diagnostic value of serum Cystatin C in renal function impairments in children with viral encephalitis].

OBJECTIVE: To study the value of serum Cystatin C (Cyst C) in the evaluation of glomerular filtration function in children with viral encephalitis. METHODS: Serum levels of Cyst C, urea nitrogen (BUN) and creatinine (Cr) were measured in 92 children with viral encephalitis and in 50 healthy children as a control group. According to glomerular filtration rate (GFR), the encephalitis group was subdivided into normal renal function, renal insufficiency in the compensatory or decompensatory stage, and renal failure /end-stage groups. RESULTS: Serum levels of Cyst C, BUN and Cr in the encephalitis group increased and GFR decreased significantly compared with those in the control group (P<0.01). With the decline of renal function, GFR decreased and serum levels of Cyst C, BUN and Cr increased gradually. Serum levels of Cyst C and GFR were significantly different among the encephaitis subgroups (P<0.01). For serum levels of BUN and Cr, there were significant differences among the subgroups except between the normal renal function and the compensatory renal insufficiency groups. Serum Cyst C level was positively correlated with serum BUN and Cr levels, and negatively correlated with GFR. CONCLUSIONS: The children with viral encephalitis have different degrees of renal impairments. Cyst C appears to be superior to BUN and Cr as a marker for the evaluation of glomerular filtration function. Measurement of serum Cyst C levels is very valuable in renal function monitoring in children with viral encephalitis.