Research
Obstetrics
Urinary podocyte excretion as a marker for preeclampsia

Presented at the 27th Annual Clinical Meeting of the Society for Maternal-Fetal Medicine, San Francisco, CA, Feb. 5-10, 2007.
https://doi.org/10.1016/j.ajog.2007.02.007Get rights and content

Objective

The objective of this study was to examine whether podocyturia, which is the urinary excretion of viable podocytes (glomerular epithelial cells), is present in urinary sediments of patients with preeclampsia. We also aimed to compare the test characteristics of podocyturia to those angiogenic factors that have been shown to play an important role in the pathogenesis of preeclampsia (s-Flt-1, PlGF, and endoglin).

Study Design

Serum angiogenic factors were measured in 44 patients with preeclampsia and 23 normotensive control patients. In a patient subset (15 cases and 16 control patients), urinary proteinuria were identified and quantified on the basis of their expressions of podocyte-specific proteins.

Results

Urinary podocyte excretion occurred in all patients with preeclampsia. The positive predictive value for the diagnosis of preeclampsia was greater for podocyturia than for any of the measured angiogenic factors.

Conclusion

Podocyturia is a highly sensitive and specific marker for preeclampsia. It may contribute to the development of proteinuria in preeclampsia.

Section snippets

Materials and Methods

This study was approved by the Institutional Review Board, and all women were consented before inclusion in the study. The diagnosis of preeclampsia was made in the presence of (a) hypertension after 20 weeks of gestation, which was defined as a blood pressure of ≥140/90 mm Hg, (b) proteinuria, which was defined as ≥300 mg of protein in a 24-hour urine specimen, and/or 1+ (30 mg/L) dipstick urinalysis in the absence of urinary tract infection and/or a predicted 24-hour urine protein of >300 mg

Podocyturia

In the women with urinary measures of podocyturia (ie, 15 cases and 16 control subjects), those women with preeclampsia or HELLP had podocin-positive cells in the urine (Figure 1A), whereas none of the normotensive control subjects had any podocin-positive cells. Thus, the sensitivity and specificity of podocyturia, as determined by the podocin-positive cells, for the diagnosis of preeclampsia were both 100%. A positive correlation between the degree of proteinuria and podocyturia, as

Comment

Our study demonstrates that podocyturia (ie, urinary excretion of podocytes) is present in patients with preeclampsia at the time of delivery. These cells retain the ability to attach to tissue culture plates in vitro, which indicates that they are viable. Urinary shedding of podocytes may contribute to proteinuria in preeclampsia, because these cells have a very limited regenerative capacity. Therefore, podocyturia may indicate podocyte loss from the glomerulus that may lead to a disruption of

Acknowledgments

We thank Mrs Angela K. Dalenberg and Mrs Catherine E. Gray from the Division of Nephrology and Hypertension for their help in developing and performing podocyturia assays, and Ms. Heather Wiste for assistance with statistical analyses.

References (18)

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Supported in part by a CR-20 grant from the Mayo Foundation (V.D.G.).

Cite this article as: Garovic VD, Wagner SJ, Turner ST, et al. Urinary podocyte excretion as a marker for preeclampsia. Am J Obstet Gynecol 2007;196:320.e1-320.e7.

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