M ZEN1,2, S PADMANABHAN1, W CHEUNG1,2, A KIRBY1, S JESUDASON 4, T ALAHAKOON1,3, V LEE1,2
1Westmead Hospital, Westmead, Australia, 2University of Sydney, Sydney, Australia, 3Westmead Institute for Maternal & Fetal Medicine, Westmead, Australia, 4Central and Northern Adelaide Renal and Transplantation Service, Royal Adelaide Hospital, Adelaide, Australia
Background: Microalbuminuria is an established marker of endothelial cell dysfunction and micro-vascular disease, and a hallmark of diabetic nephropathy. Outside of pregnancy, uACR is a well-validated tool in the diagnosis and prognosis of renal disease. In contrast, little is known about the utility of uACR in predicting adverse pregnancy outcomes within the obstetric population.
Aim: To determine if microalbuminuria can be used as a predictive marker of preeclampsia (PE) and adverse pregnancy and neonatal outcomes in women with pre-existing diabetes and to compare the prognostic utility of urinary albumin to creatinine ratio (uACR) and urinary protein to creatinine ratio (uPCR) and their ability to predict PE.
Methods: This is a multicentre prospective cohort study of 158 women with pre-existing diabetes. A spot uPCR and uACR was performed in each trimester and pregnancy and fetal outcomes were investigated using linear and logistic regression models and receiver operating characteristic (ROC) curves.
Results: Increasing levels of both uPCR and uACR in trimester 3 were associated with the occurrence of PE (p = 0.007, 0.010 respectively). In the 113 patients with normal pregnancy uPCR (<30mg/mmol) in trimester 1, microalbuminuria was found to be predictive of PE (p = 0.01) and need for operative delivery (p = 0.03).
Conclusions: In women with pre-existing diabetes, uPCR and uACR have similar ability to diagnose PE, but microalbuminuria demonstrates prognostic ability at a much earlier gestation, prior to the onset of other signs or symptoms of PE. We therefore suggest that assessing microalbuminuria rather than overt proteinuria in trimester 1 provides prognostic information in women with pre-existing diabetes and that early diabetic nephropathy confers a worse prognosis compared to diabetes without nephropathy.
Dr Zen is an obstetric fellow at Westmead Hospital. Her current research interest is in prediction, pathogenesis and outcomes of preeclampsia.