Evaluating Serum Cystatin C as A Marker of Reduced Glomerular Filtration Rate in Pregnant Women: A Better Alternative to Creatinine?

Background: Monitoring kidney function during pregnancy is vital, especially in women with hypertensive disorders like preeclampsia. Serum creatinine, although widely used, is limited in sensitivity due to physiological changes in pregnancy. Cystatin C, a novel biomarker, has emerged as a potentially superior and early indicator of glomerular filtration rate (GFR). The aim of this study was to evaluate the diagnostic performance of cystatin C compared to creatinine in pregnant women.

Methods: A cross-sectional comparative study was conducted among 180 pregnant women at a tertiary centre in Nigeria. Participants included 90 women with preeclampsia and 90 normotensive controls. The respondents were interviewed using a pre-tested, interviewer -administered, semi-structured questionnaire. Serum creatinine and cystatin C levels were measured, and estimated GFR was calculated using the CKD-EPI equation. Group comparisons and correlation analyses were performed.

Results: Mean serum cystatin C levels were significantly higher in preeclamptic women (1.09 ± 0.62 mg/L) compared to controls (0.80 ± 0.22 mg/L, p < 0.001). Although mean serum creatinine levels were slightly higher in the preeclamptic group (89.4 ± 52.5 µmol/L) than in the control group (86.9 ± 47.5 µmol/L), the difference was not statistically significant (p = 0.168). Cystatin C demonstrated a stronger inverse correlation with eGFR (r = -0.68) than creatinine (r = -0.49). Kidney dysfunction (eGFR < 60 mL/min) was detected in 11.1% of preeclamptic women using cystatin C-based threshold and absent in normotensive controls (p < 0.001).

Conclusion: Cystatin C outperforms serum creatinine in detecting early kidney dysfunction in pregnancy and may be a more reliable tool for antenatal screening, especially in high-risk populations. Its adoption could improve early diagnosis and clinical outcomes in resource-limited settings.