Priority of cystatin C among other renal biomarkers for pre-eclampsia diagnosing

Abstract

Background. Placental ischemia and renal dysfunction are crucial elements of pre-eclampsia development. Thorough renal function control enables timely delivery and minimization of complications during pregnancy. It also enables pre-eclampsia diagnosing at the pre-clinical stage. The purpose was to study serum cystatin C levels and to evaluate its efficacy in pre-eclampsia prognosis compared to creatinine and urea serum levels in pregnant patients. Materials and methods. Thirty females at their first trimester of pregnancy were enrolled. Twenty females with a history of pre-eclampsia risk factors were included into the study group, 10 healthy females without any pre-eclampsia risk factors were included into the control group. Serum levels of cystatin C, creatinine and urea were studied at 22–36 weeks of gestation. Results. Comparison of mean values in a group of females, who subsequently developed pre-eclampsia (n = 8), and average values in females without pre-eclampsia (n = 12) demonstrated following cystatin C, creatinine and urea levels: 1.34 ± 0.11 mg/l vs 0.88 ± 0.03 mg/l, a significant difference for cystatin C has been demonstrated С (р < 0.001); 78.54 ± 3.68 μmol/l vs 69.06 ± 4.94 μmol/l, a significant difference for creatinine has been demonstrated (р < 0.05); 2.79 ± 0.34 mmol/l vs 3.07 ± 0.23 mmol/l, no statistically significant difference for urea has been demonstrated (р = 0.364). In a group of pregnant females, who subsequently developed pre-eclampsia, glomerular filtration rate as calculated based on creatinine level (88.25 ± 5.76 ml/min/1.73 m2) was physiologic. However, glomerular filtration rate as calculated based on cystatin C level (58.62 ± 4.11 ml/min/1.73 m2) demonstrated a significant decrease of renal filtration capacity. In females with cystatin C level over 1.0 mg/l (n = 10), sensitivity of 87.5 % and specificity of 100 % regarding pre-eclampsia development has been demonstrated for 1.08 value. Area under the ROС curve analysis demonstrated the difference between these three markers in a group of pregnant females, who further developed pre-eclampsia. Namely, cystatin C level as a perfect marker (0.99), creatinine level as a good marker (0.78) and urea level as a poor marker (0.42) for early pre-eclampsia diagnosing. Conclusions. Our study demonstrated a significant elevation of cystatin C serum levels in pregnant patients at the pre-clinical stage of eclampsia without any increase in creatinine and urea serum levels. Cystatin C serum level is an effective and reliable marker for pre-eclampsia prognosis at second and third trimesters of pregnancy.