Garovic VD et al. (2007) Urinary podocyte excretion as a marker for preeclampsia. Am J Obstet Gynecol 196: 320.e1–320.e7

Preeclampsia is characterized by hypertension and proteinuria after 20 weeks gestation. Endothelial dysfunction is thought to have a central role in the pathogenesis of preeclampsia, but no attention had been directed towards the involvement of podocytes in this disease. Garovic et al. propose that shedding of podocytes—glomerular epithelial cells—into urine (podocyturia) might contribute to proteinuria in preeclampsia.

Of 67 recruited women, 33 had preeclampsia and 11 had HELLP syndrome, a severe form of preeclampsia. The urine of 31 patients was collected at delivery and evaluated for the presence of antibodies to four podocyte proteins—podocin, podocalyxin, nephrin and synaptopodin. Podocin proved the most accurate diagnostic marker, with podocin-positive cells present in the urine of all 15 patients with preeclampsia/HELLP, and none of the 16 normotensive healthy controls. Furthermore, the severity of podocyturia determined by podocin staining was significantly correlated with the degree of proteinuria (P = 0.04). The authors hypothesize that podocyte loss disrupts the glomerular filtration barrier, leading to proteinuria.

Several potential angiogenic markers of preeclampsia were also assessed; podocyturia had a greater positive predictive value for preeclampsia than any of these factors, which included the soluble VEGF receptor sFlt-1. In an additional evaluation, no podocin-positive cells were detected in the urine of 11 controls with gestational hypertension, essential hypertension or proteinuria not associated with preeclampsia.

The authors conclude that podocyturia is a highly sensitive and specific marker of preeclampsia at the time of delivery. To determine its utility as a screening test for preeclampsia in early pregnancy, they plan to test whether podocyturia develops before proteinuria.