The Association Between GFR Evaluated by Serum Cystatin C and Proteinuria During Pregnancy

Abstract

Introduction: Physiological changes in pregnancy result in increased cardiac output and renal blood flow, with a consequential increase in proteinuria. Data from studies of the relationship between proteinuria caused by isolated proteinuria and glomerular filtration rate (GFR) are still limited. The objective of this study was to investigate the effects of isolated proteinuria on the cystatin C–based GFR in the third trimester of pregnancy. Methods: Data were collected from pregnant women in their third trimester whose serum creatinine levels were normal. The GFR of each participant was measured using serum cystatin C levels, and proteinuria was measured using urine protein–creatinine ratios. The participants were divided into 3 groups according to their level of proteinuria: normal (300 mg/d). Changes in GFR were recorded for each group. Results: The study included 89 participants, of whom 66.3% had levels of proteinuria that did not differ from that of the normal population (101.50 mg/d was significantly associated with declined estimated glomerular filtration rate (eGFR) (r = –0.34, P = 0.01). The analysis found that proteinuria >491.27 mg/d led to a risk of GFR 101.5 mg/d, which could be an early biomarker for renal pathology rather than pregnancy physiology, suggesting that further workup and precaution is required. Keywords: acute kidney injury, albuminuria, biomarkers, pregnancy