Physiology of Pregnancy-Related Acute Kidney Injury

Renal function increases in pregnancy due to the significant hemodynamic demands of plasma volume expansion and the growing feto-placental unit. Therefore, compromised renal function increases the risk for adverse outcomes for pregnant women and their offspring. Acute kidney injury (AKI), or sudden loss of kidney function, is a significant event that requires aggressive clinical management. An AKI event in pregnancy, or in the postpartum period, significantly increases the risk of adverse pregnancy events and fetal and maternal mortality. At present, there are significant clinical challenges to the identification, diagnosis, and management of pregnancy-associated AKI due to changing hemodynamics in pregnancy that alter baseline values and to treatment limitations in pregnancy. Emerging data indicate that patients that are considered clinically recovered following AKI, which is currently assessed primarily by return of plasma creatinine levels to normal, maintain risk of long-term complications indicating that current recovery criteria mask the detection of subclinical renal damage. In association, recent large-scale clinical cohorts indicate that a history of AKI predisposes women to adverse pregnancy events even years after the patient is considered recovered from AKI. Mechanisms via which women develop AKI in pregnancy, or develop adverse pregnancy events post-AKI, are poorly understood and require significant study to better prevent and treat AKI in women. © 2023 American Physiological Society. Compr Physiol13:4869-4878, 2023. Acute kidney injury (AKI) can present during all three trimesters of pregnancy as well as postpartum, most are considered prerenal causes.The current diagnostic criteria for AKI present challenges for diagnosis in pregnant women due to that 1. Clinical studies of AKI in pregnancy are lacking and 2. Baseline renal function in pregnancy (i.e., creatinine levels) is not well established.The renal demands of pregnancy include increases in renin angiotensin aldosterone system activation, plasma volume expansion, increased sodium and fluid retention, and increased glomerular filtration rate, which is believed to be driven by the hormone relaxin, the nitric oxide system, and renal ion channel activity.Sex hormones may contribute to or be altered by AKI in pregnancy. Progesterone has been linked to the expansion of renal function in pregnancy.