Microalbuminuria as an early predictor of preeclampsia in the pre-gestational diabetic population: A prospective cohort study

Objectives: To determine if microalbuminuria can be used as a predictive marker of preeclampsia 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).

Study design: Multicentre prospective cohort study. Antenatal Diabetes in Pregnancy clinics at three tertiary referral hospitals in Western Sydney, Australia. 158 women with pre-existing diabetes requiring insulin in pregnancy. A spot uPCR and uACR was performed in each trimester. Pregnancy and fetal outcomes were investigated using linear models and receiver-operating characteristic (ROC) curves.

Main outcome measures: The primary outcome was preeclampsia (PE). Secondary outcomes investigated were other adverse pregnancy and neonatal outcomes.

Results: Increased 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 (<30 mg/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 appear to 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 requiring insulin and should be used routinely to evaluate risk of PE in this high-risk cohort of women.