BACKGROUND: Nephrotic syndrome occurs very rarely, in only about 0.01%–0.02% of all pregnancies, and de novo minimal change disease during pregnancy is especially rare. Nephrotic syndrome and, especially, minimal change disease are highly responsive to steroids, and preterm labor may be avoidable if the maternal condition is improved with steroid therapy. Therefore, prompt diagnosis and proper management are critical to maternal and fetal outcome when severe proteinuria occurs during pregnancy.

CASE REPORT: A 30-year-old pregnant Japanese woman presented with systemic edema, oliguria, and severe proteinuria and hypoalbuminemia at 25 weeks of gestation, although she was normotensive. The patient had high urinary protein selectivity. Her illness was diagnosed as de novo nephrotic syndrome with high steroid responsiveness rather than pre-eclampsia. She began steroid pulse therapy the day after admission. Complete remission was confirmed after 3 weeks. The patient did not relapse during pregnancy and delivered a healthy male baby at 37 weeks of gestation. A renal biopsy at a relapse after delivery confirmed minimal change disease.

CONCLUSIONS: In pregnant women with de novo minimal change disease, serious maternal and/or fetal complications may occur if severe proteinuria and hypoalbuminemia are unabated for an extended time. Evaluation of urinary protein selectivity is noninvasive and useful for prediction of steroid responsiveness. Results of urinary protein selectivity can be obtained earlier than results of renal biopsy. Renal biopsy during pregnancy is not always necessary for initiation of steroid therapy. Rapid initiation of steroid pulse therapy may enable quicker achievement of remission and prevent serious perinatal complications.

Keywords: nephrotic syndrome, Oliguria, Pre-Eclampsia, Proteinuria