Excretion patterns of large and small proteins in pre-eclamptic pregnancies

Abstract

Objective. Pre-eclampsia is a serious pregnancy complication causing both fetal and maternal distress. Proteinuria is a diagnostic criterion frequently determined by albuminuria. We determined the protein excretion pattern of additional proteins, immunoglobulin G, transferrin, α1-microglobulin and β2-microglobulin, in urine samples collected prospectively during pre-eclamptic and healthy pregnancies. Design. A prospective cohort study of 1 631 consecutive pregnant women. Setting. A Danish regional hospital. Sample. Thirty-two women with pre-eclampsia and 185 healthy control women were identified from the cohort. Urine samples were obtained from the 18th week until delivery and divided into six gestational intervals. Methods. Protein analyses of urine immunoglobulin G, transferrin, α1-microglobulin and β2-microglobulin were done with a sandwich ELISA method. Main Outcome Measures. Urine levels of specific proteins during pre-eclamptic and healthy pregnancies. Results. Immunoglobulin G and transferrin were significantly increased in pre-eclampsia after the 30th week of pregnancy. α1-Microglobulin and β2-microglobulin were differently excreted and found to be higher after the 36th week of pregnancy in pre-eclampsia, but only α1-microglobulin increased significantly. Conclusions. Immunoglobulin G, transferrin, α1- and β2-microglobulin excretion patterns indicate initial glomerular damage followed by altered tubular handling of proteins. © 2011 Nordic Federation of Societies of Obstetrics and Gynecology.