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

Table 1 Characteristic features of acute kidney injury in acute fatty liver of pregnancy

Feature	Description
Incidence	Occurs in 60%-70% of AFLP cases (vs < 15% in HELLP)
Clinical severity	Often moderate to severe; RRT required in < 5%
Initial presentation	AKI may be an early or presenting feature
Liver function tests	AST/ALT: Moderately elevated (< 300 IU/L)- Bilirubin: Markedly elevated. GGT: Usually normal (↑ in viral hepatitis)
Differentiation	AFLP: Microvesicular steatosis → cholestasis → ↑ bilirubin > transaminases. HELLP/Hepatitis: Hepatocellular necrosis → ↑. AST/ALT > bilirubin- 20% of AFLP cases may overlap with HELLP- May show features of TMA
Metabolic disturbances	Hyperuricemia: Markedly raised (hepatic + renal causes). Acidosis: Mixed lactic and anion gap acidosis
Urinalysis	Mild-moderate proteinuria in about 70%; hematuria uncommon
AKI type/urine output	Non-oliguric AKI: Common in mild/prerenal cases- Oliguric AKI (about 20%): Often from ATN or hepatorenal-like physiology. Rare postpartum cases present abruptly with oliguria and MODS
Recovery pattern	Typically rapid after delivery with supportive care. Most recover in 1-3 weeks. Delayed in MODS
Liver vs kidney recovery	Liver: Transaminases drop rapidly post-delivery; bilirubin and synthesis markers recover slowly. Kidney: Gradual, linear recovery
Post-recovery issues	Rare delayed/biphasic recovery. Risk of second hits (sepsis, DIC, volume depletion). Temporary RRT may be needed. Usually reversible (renal cortical necrosis very rare)
Renal histopathology	Commonly ATN without glomerular/immune complex involvement; tubular fatty acid deposition reported

AKI: Acute kidney injury; RRT: Renal replacement therapy; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; GGT: Gamma glutamyl transferase; HELLP: Hemolysis, elevated liver enzymes, and low platelets; DIC: Disseminated intravascular coagulation; MODS: Multiple organ dysfunction syndrome; ATN: Acute tubular necrosis; TMA: Thrombotic microangiopathy; AFLP: Acute fatty liver of pregnancy.

Table 2 Summary of relevant studies on acute kidney injury in acute fatty liver of pregnancy

Ref.	Year	Key AKI findings	Study population	AKI incidence	Key outcomes
Slater et al[13]	1984	Renal histology showed lipid accumulation in 50% of cases	Case series	All cases had severe AKI	Renal changes may be early features of AFLP
Rolfes et al[29]	1985	Histology showed acute tubular necrosis and one case of endotheliosis	35 autopsied cases	Most had AKI; 20% oliguric AKI; 1 required RRT	Highlights renal pathology in AFLP
Castro et al[8]	1999	AKI was an early sign even with normal LFT; 21.4% had preeclampsia	28 cases	All had AKI	Full renal and hepatic recovery; AFLP was termed as “reversible peripartum liver failure”
Vigil-De Gracia et al[24]	2001	AKI occurred early in AFLP, later in HELLP; serum lipids levels lower in AFLP	Retrospective study	90% in AFLP vs 20% in HELLP	Renal function normalized at discharge
Ch'ng et al[10]	2002	Renal dysfunction-a key finding in Swansea criteria	Prospective analysis		60% had prolonged hospitalization due to multiorgan involvement
Knight et al[1]	2008	Observed Improved maternal outcome	Prospective cohort study	58% had AKI; 3.5% required RRT	60% ICU admission; 1 maternal death
Tang et al[58]	2012	CBPT improved renal and hepatic recovery	17 AFLP cases with AKI		Maternal mortality 5.9%
Nelson et al[2]	2013	Hepatorenal dysfunction was nearly universal	Retrospective study (n = 51)	96% had AKI; 2% required RRT	Recovery in 7-10 days postpartum. Renal recovery patterns described
Xiong et al[37]	2015	High RRT requirement (32%)	Single-center series	72%	Full renal recovery at discharge
Zhang et al[21]	2016	Higher ICU admission and multiorgan dysfunction; 16% had diarrhea	Retrospective study (n = 56)	52%	Maternal mortality 7%
Gao et al[23]	2018	Serum creatinine identified as mortality risk factor	Retrospective study (n = 133)	55.6%; RRT 241%	Maternal mortality 16.5%
Chen et al[17]	2019	AKI was most common complication	Retrospective (n = 44)	79.5%	AKI usually moderate; prognosis favorable
Meng et al[16]	2021	Developed a mortality prediction model using serum creatinine and other variables	Retrospective (n = 106)	67%	Maternal mortality 9.4%
Vijay et al[22]	2023	5% had preeclampsia; many required RRT	Retrospective	36.8%	Maternal mortality 21%
Peng et al[59]	2024	Serum creatinine predicted poor outcomes	Retrospective (n = 78)		Outcomes improved with artificial liver support

AKI: Acute kidney injury; AFLP: Acute fatty liver of pregnancy; LFT: Liver function test; HELLP: Hemolysis elevated liver enzymes, and low platelets; RRT: Renal replacement therapy; ICU: Intensive care unit; CBPT: Combined blood purification treatment; LFT: Liver function test.