Post-partum podocyturia following pre-eclamptic pregnancy

Urine podocin mRNA expression and urine podocin : nephrin mRNA expression ratio (PNR) increase with increasing proteinuria during pregnancy complicated with pre-eclampsia (PE). This suggests that urine podocytes with reduced nephrin mRNA expression are abundant in pathological podocyturia. The aim of this study was therefore to determine post-partum changes in podocyturia and PNR in relation to proteinuria after pre-eclampsia (PE).

A total of 137 peripartum urine specimens, consisting of 72 and 65 from 24 and 30 women with PE and normotensive control pregnancies (NCP), respectively, were studied. Determination of urine protein and creatinine concentration and quantitative analysis of podocyte-specific podocin and nephrin mRNA expression were carried out using reverse transcription-polymerase chain reaction in pelleted urine samples. Podocyturia was monitored via urine podocin mRNA expression. Podocyturia and proteinuria were normalized by urine creatinine concentration.

Podocyturia and urine PNR decreased with decreasing proteinuria as well as with increasing time after delivery in the urine from PE women. In physiological proteinuria (i.e. protein : creatinine ratio [P/Cr] 0.005-0.1 mg/mg), however, both podocyturia and PNR were significantly greater in the urine from PE women compared with NPC women, although P/Cr was similar between the groups (median, 0.037 mg/mg for PE vs 0.029 mg/mg for NCP).

Podocyturia decreases with decreasing proteinuria in PE women after childbirth. In PE women, however, pathological podocyturia consisting of podocytes with decreased nephrin mRNA expression persisted even after proteinuria decreased to a level similar to that in NCP women.