Metabolic dysfunction-associated steatotic liver disease

Epidemiology & Risk Factors

• Most common cause of chronic liver disease in Western nations.
• Strongly associated with Metabolic Syndrome (MetS).
• Key risk factors:
  • Obesity (particularly increased visceral adiposity).
  • Type 2 Diabetes Mellitus (DM2) and insulin resistance (major driver of progression to steatohepatitis).
  • Dyslipidemia (specifically hypertriglyceridemia and low HDL).
  • Hypertension (HTN).
  • Age (prevalence increases with age, though pediatric cases are rising due to childhood obesity).

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Clinical Features

• History:
  • Frequently asymptomatic; typically identified incidentally on routine LFTs or abdominal imaging.
  • If symptomatic, patients present with fatigue, malaise, or dull RUQ discomfort.
• PE:
  • Hepatomegaly (most common physical examination finding).
  • Acanthosis nigricans (hyperpigmented, velvety plaques indicating severe insulin resistance).
  • Stigmata of portal HTN/cirrhosis (e.g., splenomegaly, spider angiomas, ascites) only present in advanced, decompensated stages.

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Diagnosis

• Initial/Screening:
  • RUQ Ultrasound (US): Demonstrates hyperechoic/bright liver with posterior acoustic attenuation.
  • FIB-4 Index: First-line non-invasive test (NIT) for fibrosis risk stratification (calculated using age, AST, ALT, and platelets).
    • FIB-4 < 1.3 (< 2.0 in patients ≥65): Low risk of advanced fibrosis.
    • FIB-4 1.3–2.67: Indeterminate risk; requires secondary testing.
    • FIB-4 > 2.67: High risk of advanced fibrosis; warrants direct hepatology referral.
• Secondary Non-Invasive Testing (if FIB-4 is indeterminate):
  • Vibration-Controlled Transient Elastography (VCTE / FibroScan) or MRE to measure liver stiffness.
• Confirmatory/Gold Standard:
  • Liver Biopsy: Indicated if diagnosis is uncertain, to rule out co-existing etiologies, or to stage fibrosis.
    • Histology reveals macrovesicular steatosis (>5% of hepatocytes), lobular inflammation, hepatocyte ballooning, and Mallory-Denk bodies.
• Key Labs:
  • Mild elevation of ALT and AST (ALT typically > AST; a reversal to AST > ALT suggests progression to cirrhosis).
  • Mild elevation of ALP.
  • Exclude other causes: negative viral hepatitis serologies (HBV, HCV), normal iron studies (ferritin, transferrin saturation), normal ceruloplasmin, and negative ANA/ASMA.

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Differential Diagnostics

• Alcohol-Associated Liver Disease (ALD):
  • Differentiating feature: History of significant alcohol intake (>140g/week for females, >210g/week for males). AST:ALT ratio is typically >2:1.
• Medication-Induced Steatosis:
  • Differentiating feature: History of exposure to steatogenic agents (e.g., amiodarone, methotrexate, valproate, tamoxifen, systemic corticosteroids).
• Autoimmune Hepatitis (AIH):
  • Differentiating feature: Elevated serum IgG levels, positive ANA and ASMA, and interface hepatitis on biopsy.
• Hereditary Hemochromatosis:
  • Differentiating feature: Elevated transferrin saturation (>45%), high ferritin, and HFE gene mutation.
• Wilson Disease:
  • Differentiating feature: Younger age of onset (<35 years), decreased ceruloplasmin, Kayser-Fleischer rings, and neuropsychiatric symptoms.

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Management

• First-line (Lifestyle Interventions):
  • Weight loss: Target ≥7-10% of total body weight (promotes resolution of steatohepatitis and regression of fibrosis).
  • Dietary modification: Mediterranean diet (low carbohydrates, high monounsaturated fats), strict avoidance of fructose and sweetened beverages.
  • Exercise: 150 minutes/week of moderate-intensity aerobic and resistance training.
  • Aggressive management of CV risk factors (statin therapy for dyslipidemia, tight glycemic control, BP control).
• Second-line (Pharmacotherapy):
  • For patients with concurrent DM2: GLP-1 receptor agonists (e.g., semaglutide) or Pioglitazone.
  • For non-cirrhotic MASH with moderate-to-advanced fibrosis (stages F2-F3): Resmetirom (thyroid hormone receptor-beta selective agonist).
  • Vitamin E (800 IU/day): Considered for non-diabetic patients with biopsy-proven MASH.
• Refractory / Advanced Disease:
  • Bariatric surgery: Recommended for eligible patients (BMI ≥35 kg/m²) with refractory MASLD/MASH to achieve sustained weight loss.
  • Liver transplantation: Indicated for decompensated MASH-related cirrhosis or MASH-associated HCC.

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Complications

• Progression to Metabolic Dysfunction-Associated Steatohepatitis (MASH).
• Liver Cirrhosis and portal HTN.
• Hepatocellular Carcinoma (HCC): Can develop in patients with MASLD/MASH even in the absence of cirrhosis.
• Cardiovascular Disease (CVD): The leading cause of mortality in patients with MASLD/MASH.