Increased antiangiogenetic factors in severe proteinuria without hypertension in pregnancy: is kidney biopsy necessary?

Acute onset of severe proteinuria during pregnancy obliges physicians to clinically discriminate between gestational proteinuria (GP) and new onset of nephritis. A multiparous woman developed severe proteinuria (5.8 g/day) without hypertension at 32 weeks of gestation. We measured the maternal level of soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng), which were extremely high (41.3 and 54.8 ng/ml, respectively), leading us to consider this condition as GP rather than acute onset of nephritis. Thus, we did not perform a kidney biopsy and did not administer a steroid agent. Non-reassuring fetal status required emergency Cesarean section at 33 weeks. Proteinuria decreased to 0.36 g/day at 12 weeks after delivery, and finally disappeared 26 weeks postpartum. Measurement of sFlt-1 and sEng in a pregnant woman with severe proteinuria without hypertension may assist in differential diagnosis of GP from acute onset of nephritis, and thus help to decide whether to perform kidney biopsy during pregnancy.