Acute kidney injury associated with acute fatty liver of pregnancy: An update on a rare clinical entity

Abstract

Acute fatty liver of pregnancy (AFLP) is a rare but potentially life-threatening liver disease associated with mitochondrial dysfunction. It is characterized by microvesicular hepatic steatosis and typically occurs in the third trimester, though it may rarely present postpartum. AFLP is considered a non-thrombotic microangiopathy (TMA) but may present with overlapping TMA features. Its incidence ranges from 1 in 7000 to 1 in 20000 pregnancies, although milder cases may go unrecognized. AFLP can rapidly progress to acute liver failure and 20% to 40% of affected women exhibit clinical features of preeclampsia. Acute kidney injury (AKI) is a frequent complication, observed in 55% to 75% of AFLP cases, which is significantly higher than the 7% to 20% occurrence seen in preeclampsia or hemolysis, elevated liver enzymes, and low platelets syndrome. The exact mechanism behind AKI in AFLP remains unclear, but renal histology has shown tubular deposits of free fatty acids, which correlate with current theories regarding liver pathology. While AFLP-associated AKI is often reversible after delivery, some patients may develop persistent AKI that requires dialysis. Therapeutic plasma exchange (TPE) has been explored in these cases, but available evidence is limited. This review summarizes the current understanding of the epidemiology, pathophysiology, clinical features, and management of AKI in the context of AFLP, and discusses the potential role of adjunctive therapies such as TPE.

Keywords: Acute kidney injury; Acute tubular necrosis; Acute fatty liver of pregnancy; Pregnancy complications; Therapeutic plasma exchange

Core Tip: Acute kidney injury (AKI) associated with acute fatty liver of pregnancy (AFLP) occurs more frequently than AKI related to preeclampsia or hemolysis, elevated liver enzymes, and low platelets syndrome; however, it is generally non-oliguric and of relatively low severity. In some cases, kidney function may not fully recover after delivery and could require dialysis. Rarely, AFLP can manifest in the postpartum period, which presents a diagnostic challenge due to lack of prodromal symptoms and occurrence of severe AKI. AKI is key characteristic of AFLP and is included in both its diagnostic and prognostic criteria. Therapeutic plasma exchange may be considered in patients with persistent hepatic or renal dysfunction following delivery. Given that rapid recognition and prompt delivery are crucial for managing AFLP, there is a need for biomarkers, similar to the soluble fms-like tyrosine kinase-1/placental growth factor (sFlt-1/PlGF) ratio used in preeclampsia, that can facilitate earlier diagnosis and treatment.