Abstract
 Background:  Preeclampsia is a complex and serious multisystem disorder of pregnancy with a worldwide incidence of  5-7% and contributes significantly to maternal and perinatal morbidity and mortality. Altered renal function is an essential component of the pathophysiological process in PE, so close monitoring of renal function is important to ensure a timely  delivery before serious renal damage occurs.
 Aim of the Work:  To evaluate diagnostic value of cystatin C serum levels as an alternative marker of renal function in women with severe preeclamptic toxemia versus matching cases of normal pregnancy and compare it with the traditional markers of renal function, Creatinine, urea and serum uric acid.
 Patients and Methods:  A case-control study includes 80 Primigravidae with singleton pregnancy and gestation ≥28 weeks and were divided into two groups, Group 1: (40 patients) with severe preeclampsia and Group 2: (40 patients) as a control group (normotensive and nonproteinuric). Markers of kidney function were investigated in two groups of pregnant women and comparison between both groups as regards to cystatin C serum levels, creatinine, blood urea and serum uric  acid was done.
 Results:  The difference in the mean serum uric acid level (5.10±0.96 versus 4.70±0.63mg/dl) was significantly higher in preeclampsia (p=0.027), the specificity was 100% and sensitivity of the test was 87.5%, the difference in the mean serum concentration of creatinine (0.94±0.16 versus 0.86±  0.12mg/dl) was significantly higher in preeclampsia (p=0.028), the specificity of the test was 100% and the sensitivity was
 82.5%. Serum cystatin C level has a mean (1.26±0.21 versus 0.75±0.05mg/l) which was significantly higher in preeclampsia (p=0.001) with a specificity 100% and sensitivity 96%. Conclusion: It is concluded that among serum creatinine, blood urea, serum uric acid & serum cystatin C, Serum cystatin C is the earliest & a better marker of renal dysfunction in preeclampsia.