Utility of [TIMP-2]•[IGFBP7] for Risk Prediction of Acute Kidney Injury (AKI) in Pregnancy [ID 791]

INTRODUCTION: Early acute kidney injury (AKI) detection in the peripartum period is complicated by pregnancy-related physiological changes. Urinary cell cycle arrest biomarkers, tissue inhibitor of metalloproteinase (TIMP-2) and insulin growth factor binding protein (IGFBP7), are useful for nonobstetric AKI prediction and may also have utility in obstetric populations. We examined urinary [TIMP-2]•[IGFBP7] in a healthy obstetric cohort. We also compared [TIMP-2]•[IGFBP7] in high-risk patients with and without AKI, and with and without preeclampsia. METHODS: In a prospective observational study, we measured urinary [TIMP-2]•[IGFBP7] in healthy pregnant outpatients during the first (n=31), second (n=33), and third (n=19) trimesters, and in high-risk hospitalized pregnant patients (n=90). Acute kidney injury was defined per KDIGO criteria. Biomarker reference ranges for each trimester were defined as the inner 95th percentile of all rank-ordered data, and biomarker levels between pregnant women with and without AKI, and with and without preeclampsia, were compared using the Wilcoxon rank-sum test. RESULTS: Reference intervals for [TIMP-2]•[IGFBP7] in healthy pregnant women are 0.05–6.5, 0.05–2.4, and 0.05–1.2 (ng/mL) 2 /1,000 in the first, second, and third trimesters, respectively. In the hospitalized cohort, 7% developed AKI, and 59% developed preeclampsia. Median [IQR] [TIMP-2]•[IGFBP7] levels were 0.4 [0.175, 0.675] in patients with AKI, 0.3 [0.1, 0.6] in patients without AKI ( P =.48), and 0.3 [0.15, 0.55] in patients with preeclampsia, and 0.2 [0.1, 0.6] in patients without preeclampsia ( P =.38). CONCLUSIONS/IMPLICATIONS: We established reference levels for [TIMP-2]•[IGFBP7] in a healthy obstetric population. However, biomarker levels were not significantly higher in patients with diagnosed AKI or with preeclampsia, highlighting the need for alternative clinical biomarkers for early obstetric AKI detection.