Introduction
Preeclampsia (PE) is identified in approximately 4–5% of pregnancies and is the second most common cause of pregnancy-related maternal death. More than 90% of maternal deaths occur in low-and lower-middle-income countries1,2. PE leads not only to maternal death and short-term maternal morbidities but also to long-term cardiovascular sequelae3. By terminating pregnancy through early diagnosis, more than half of all hypertension-related mortality can be prevented4. The diagnosis of PE is established when women have high blood pressure and evidence of multi-organ involvement, such as proteinuria, thrombocytopenia, liver involvement, or cerebral symptoms5,6. However, this method requires considerable time and specialized facilities to obtain laboratory findings and evidence of abnormal protein excretion in urine. In countries where this method cannot be easily performed, the diagnosis and treatment of PE may be delayed. To date, efforts have been made to develop easy and simple methods for the diagnosis of PE. However, they are still in the developmental stage and have not been fully validated.
Nephrin is a transmembrane protein of the slit diaphragm in podocytes and consists of a renal filtration barrier7. In kidney injuries, damaged podocytes lead to alterations of the slit diaphragm and foot process structure, resulting in nephrinuria. Thus, urine nephrin is well known as an early biomarker for glomerular injury in glomerulonephritis and diabetic nephropathy8-11. In addition, some studies have revealed that women with PE have nephrinuria, which is considered a marker for possible renal damage and a predictive indicator of severe PE12-15. Using aptamer-based technology, we attempted to develop a point-of-care test quantifying nephrin excretion in urine, which could be used to rapidly diagnose PE. The purpose of this study was to develop an assay to verify the accuracy and performance of this test in the diagnosis of PE.