What is the typical lipid profile in patients with Acute Fatty Liver of Pregnancy (AFLP)?

Lipid Profile in Acute Fatty Liver of Pregnancy (AFLP)

The typical lipid profile in AFLP includes hypoglycemia, elevated uric acid, coagulopathy with prolonged PT/PTT, reduced fibrinogen levels, and elevated lactate dehydrogenase, which are critical laboratory markers for diagnosis and management. 1

Diagnostic Laboratory Findings in AFLP

AFLP presents with a characteristic pattern of laboratory abnormalities that help differentiate it from other pregnancy-related liver disorders:

Key Lipid and Metabolic Abnormalities

• Hypoglycemia (<72 mg/dL): Present in up to 94.2% of cases 2
• Coagulopathy:
  • Prolonged prothrombin time (PT >14 seconds)
  • Prolonged partial thromboplastin time (PTT >34 seconds)
  • Reduced fibrinogen levels
  • Disseminated intravascular coagulation (DIC) in approximately 10% of patients 1
• Elevated lactate dehydrogenase (LDH)
• Elevated uric acid (>5.7 mg/dL)

Associated Laboratory Findings

• Elevated transaminases (AST or ALT >42 IU/L)
• Elevated bilirubin (>0.8 mg/dL)
• Elevated ammonia (>42 IU/L)
• Leukocytosis (>11 × 10^6/L)
• Renal impairment (creatinine >1.7 mg/dL)

Pathophysiology of Lipid Abnormalities in AFLP

The lipid abnormalities in AFLP are directly related to its underlying pathophysiology:

• AFLP is strongly associated with fetal mitochondrial long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency 1, 3
• This deficiency leads to accumulation of hepatotoxic long-chain 3-hydroxy-fatty acyl metabolites that pass from fetal to maternal circulation
• These metabolites cause microvesicular hepatic steatosis (fatty infiltration of the liver)
• The resulting hepatic dysfunction leads to impaired glucose production (hypoglycemia), decreased synthesis of coagulation factors (coagulopathy), and other metabolic derangements

Diagnostic Criteria

The Swansea criteria are used for diagnosis of AFLP, requiring 6 or more of the following findings 1, 3:

• Vomiting
• Abdominal pain
• Polydipsia/polyuria
• Encephalopathy
• Elevated transaminases (AST or ALT >42 IU/L)
• Elevated bilirubin (>0.8 mg/dL)
• Hypoglycemia (<72 mg/dL)
• Leukocytosis (>11 × 10^6/L)
• Elevated uric acid (>5.7 mg/dL)
• Elevated ammonia (>42 IU/L)
• Ascites or bright liver on ultrasound
• Renal impairment (creatinine >1.7 mg/dL)
• Coagulopathy (PT >14 seconds or PTT >34 seconds)
• Microvesicular steatosis on biopsy

Clinical Implications and Management

The lipid and metabolic abnormalities in AFLP have significant implications for management:

1. Hypoglycemia management is critical as it can lead to maternal and fetal morbidity
2. Coagulopathy correction is essential to prevent hemorrhagic complications
3. Monitoring for DIC is necessary as it complicates approximately 10% of cases 1

Differentiating AFLP from Other Pregnancy-Related Liver Disorders

The lipid profile helps differentiate AFLP from other conditions:

• HELLP syndrome: Both can have elevated LFTs, but profound hypoglycemia and coagulopathy are more characteristic of AFLP
• Preeclampsia: Typically lacks the severe hypoglycemia and coagulopathy seen in AFLP

Pitfalls and Caveats

1. Delayed recognition: The lipid abnormalities may initially be subtle; serial monitoring is essential
2. Confusing with HELLP syndrome: Both conditions can coexist, making diagnosis challenging
3. Relying solely on transaminase levels: While elevated, they are typically lower than in viral hepatitis
4. Missing hypoglycemia: This is a critical diagnostic feature that may be overlooked
5. Underestimating coagulopathy: Can rapidly worsen and lead to life-threatening hemorrhage

Early recognition of the characteristic lipid profile in AFLP and prompt delivery are critical for reducing maternal mortality, which has improved from historical rates of 92% to less than 10% in recent years 1.