Non-Alcoholic Fatty Liver Disease
A buildup of fat in the liver caused by metabolic issues like obesity and diabetes, which can lead to liver inflammation, scarring, and failure.
Emergency Management: Hematemesis from ruptured esophageal varices requires emergent fluid resuscitation, IV octreotide (50 mcg bolus followed by 50 mcg/hr infusion), IV ceftriaxone, and urgent upper endoscopy for banding.
Non-Alcoholic Fatty Liver Disease (now transitioning to the term Metabolic dysfunction-Associated Steatotic Liver Disease, MASLD) is characterized by excessive hepatic fat accumulation (steatosis) without secondary causes such as heavy alcohol consumption or viral hepatitis. It encompasses a spectrum ranging from isolated steatosis to non-alcoholic steatohepatitis (NASH), leading to fibrosis and cirrhosis.
Detailed Overview
It is the hepatic manifestation of metabolic syndrome. The condition progresses when simple steatosis is subjected to oxidative stress and lipotoxicity, triggering inflammation (NASH/MASH). Chronic inflammation activates hepatic stellate cells, which deposit collagen and cause fibrosis. It is rapidly becoming the leading indication for liver transplantation worldwide and increases the risk for hepatocellular carcinoma even before cirrhosis develops.
Epidemiology & Demographics
Global prevalence is estimated at 25-30%. It affects up to 70-90% of individuals with obesity or type 2 diabetes. Hispanics have the highest prevalence in the US.
Etiological Mechanism
Driven by systemic insulin resistance and dyslipidemia in the setting of excess caloric intake. Genetic polymorphisms, notably in the PNPLA3 gene, strongly predispose individuals to hepatic fat accumulation.
Primary Causes
Insulin resistance leading to increased free fatty acid flux to the liver, increased de novo lipogenesis, and decreased beta-oxidation.
The 'two-hit' or 'multiple-hit' hypothesis. Hit 1: Insulin resistance causes peripheral lipolysis, flooding the liver with free fatty acids (FFAs). The liver packages these into triglycerides, causing steatosis. Hit 2: Lipotoxicity from specific lipid species (e.g., ceramides, diacylglycerols) causes mitochondrial dysfunction and oxidative stress. This induces hepatocyte apoptosis, releasing damage-associated molecular patterns (DAMPs) that activate Kupffer cells. The ensuing inflammatory cascade activates hepatic stellate cells, which transform into myofibroblasts and deposit extracellular matrix (fibrogenesis).
Diagnostic Criteria & Guidelines
Requires imaging or histologic evidence of hepatic steatosis (>= 5% of hepatocytes) AND absence of significant alcohol consumption (<21 standard drinks/week for men, <14 for women) AND absence of competing etiologies (e.g., viral hepatitis, steatogenic drugs like amiodarone).
Weight loss is the cornerstone. 7-10% body weight loss resolves steatohepatitis and can regress fibrosis. Dietary modification (Mediterranean diet) and moderate-intensity exercise (150 mins/week). Optimization of metabolic comorbidities (statins for dyslipidemia, rigorous glycemic control).
Second-Line & Adjunctive Therapy
GLP-1 receptor agonists (e.g., Semaglutide 2.4 mg SQ weekly) for weight management and metabolic control. Pioglitazone (30 mg PO daily) can improve histology in biopsy-proven NASH. Resmetirom (THR-beta agonist) recently FDA approved for NASH with F2-F3 fibrosis.
Surgical & Procedural Management
Bariatric surgery (e.g., Roux-en-Y gastric bypass) for eligible patients (BMI > 35 with comorbidities) is highly effective at resolving NASH. Liver transplantation for decompensated cirrhosis.
Patient Counseling & Advice
Emphasize that the condition is reversible in early stages with significant lifestyle changes. Warn that cardiovascular disease is their highest mortality risk, emphasizing the need for blood pressure and lipid control.
Follow-Up & Monitoring Schedule
Reassess metabolic risk factors every 6 months. Non-invasive fibrosis testing (FIB-4 or FibroScan) every 1-2 years. If cirrhotic, HCC screening with ultrasound every 6 months.
Preventive Strategies
Maintaining a healthy body mass index (BMI 18.5-24.9), routine screening for and management of diabetes and hyperlipidemia.
NAFL has a generally benign hepatic prognosis, but high cardiovascular risk. NASH with advanced fibrosis (F3/F4) has a high risk of progression to end-stage liver disease and significantly reduced life expectancy.