Nonalcoholic Fatty Liver Disease (NAFLD)

NAFLD is often clinically silent in its early stages. Identification relies on a high index of suspicion in patients with metabolic risk factors and appropriate use of noninvasive screening tools. Primary care clinicians are uniquely positioned to identify at-risk individuals before significant liver injury has occurred.

Risk Factors for NAFLD

Diagnostic Approach in Primary Care

The principal determinant of clinical outcomes in NAFLD is the stage of liver fibrosis, not the presence of steatosis or even NASH per se. Noninvasive fibrosis assessment is now central to NAFLD management pathways and should be performed in all patients with confirmed or suspected NAFLD.

FIB-4 Index (First-Line Tool)

The FIB-4 index is calculated using the patient's age, AST, ALT, and platelet count. It is recommended as the first-line noninvasive fibrosis assessment tool by EASL, AASLD, and Australian hepatology consensus guidelines.

Formula: FIB-4 = (Age × AST) / (Platelet count × √ALT)

All values in standard units: age in years, AST and ALT in U/L, platelet count in ×10⁹/L.

NAFLD Fibrosis Score (Second-Line)

The NAFLD fibrosis score incorporates age, BMI, impaired fasting glucose/diabetes, AST/ALT ratio, platelet count, and albumin. It is used as a second-line test when the FIB-4 is indeterminate (1.3–2.67). A score >0.676 indicates high probability of advanced fibrosis; a score <–1.455 excludes advanced fibrosis. Values between these thresholds are indeterminate.

Enhanced Liver Fibrosis (ELF) Test

The ELF test measures three direct serum biomarkers of fibrogenesis: hyaluronic acid, tissue inhibitor of metalloproteinase-1 (TIMP-1), and procollagen III amino-terminal peptide (PIIINP). An ELF score ≥9.8 indicates advanced fibrosis. The ELF test is available in Australia through major pathology providers (e.g., Sonic Pathology, Douglass Hanly Moir) and is Medicare-rebatable in selected clinical contexts.

FibroScan (Transient Elastography)

FibroScan (transient elastography) measures liver stiffness as a surrogate for fibrosis stage. It is widely available across major Australian metropolitan and regional centres. Controlled attenuation parameter (CAP) is simultaneously obtained and quantifies steatosis severity.

Lifestyle intervention remains the cornerstone and most effective treatment for NAFLD across all stages. Sustained weight loss of ≥7–10% of total body weight has been shown in randomised controlled trials to resolve NASH, reduce hepatic steatosis, and — in earlier stages — reverse fibrosis. The evidence supports a multidisciplinary approach combining dietary modification, structured physical activity, and targeted management of metabolic comorbidities.

Weight Loss Targets

Dietary Recommendations

• Mediterranean-style diet is the most evidence-based dietary pattern for NAFLD: rich in extra-virgin olive oil, vegetables, legumes, whole grains, nuts, fish; moderate poultry; limited red meat, processed foods, and added sugars.
• Reduce fructose and added sugars: Fructose-containing beverages (soft drinks, fruit juices) are strongly associated with hepatic de novo lipogenesis. Complete elimination of sugar-sweetened beverages is recommended.
• Reduce ultra-processed foods: High-calorie, nutrient-poor foods promote weight gain and metabolic dysfunction.
• Limit alcohol: Even within "safe" limits, alcohol may worsen hepatic inflammation in patients with NASH. Advisable to minimise or abstain.
• Coffee: Moderate coffee consumption (2–3 cups/day) is associated with reduced fibrosis progression and is not contraindicated.
• Referral to an accredited practising dietitian (APD) is strongly recommended — available under Medicare Chronic Disease Management (CDM) plans (Item 10954, up to 5 allied health sessions per calendar year).

Physical Activity

• Aerobic exercise: ≥150 min/week of moderate-intensity activity (brisk walking, cycling, swimming) or ≥75 min/week of vigorous activity. Reduces hepatic steatosis independent of weight loss.
• Resistance training: ≥2 sessions/week targeting major muscle groups. Improves insulin sensitivity and may reduce intrahepatic fat.
• Reduce sedentary time: Prolonged sitting is independently associated with NAFLD severity. Break up sitting every 30–60 minutes.
• Exercise physiology referral (MBS Item 10953 under CDM plans) is recommended for patients requiring structured exercise prescription.

Pharmacological Management of Metabolic Comorbidities

Lipid and Blood Pressure Management

• Statins: Safe to use in NAFLD/NASH and cirrhosis (Child-Pugh A). Do not worsen liver disease. Strongly indicated for cardiovascular risk reduction — the leading cause of death in NAFLD. Atorvastatin 20–80 mg or rosuvastatin 10–40 mg as first-line. Monitor LFTs at baseline, then only if clinically indicated.
• ACE inhibitors / ARBs: Preferred antihypertensives in NAFLD. May have anti-fibrotic properties. Perindopril, ramipril, telmisartan, valsartan are commonly used agents.
• Empagliflozin / Dapagliflozin (SGLT2 inhibitors): Emerging evidence for hepatic steatosis reduction; cardiovascular and renal benefits; weight loss of 2–3 kg. Increasingly used as second-line antidiabetics in T2DM + NAFLD.

Bariatric Surgery

Bariatric surgery (laparoscopic sleeve gastrectomy, Roux-en-Y gastric bypass) should be considered in patients with BMI ≥40 (or ≥35 with significant comorbidities including NASH) who have failed sustained lifestyle intervention and pharmacological weight management. Surgery produces durable weight loss of 20–35%, with histological resolution of NASH in 80–90% and fibrosis improvement in 50–70% at 1–5 years post-operatively. Referral to an accredited bariatric surgical service is recommended. Medicare and private health insurance may cover costs if eligibility criteria are met.

Timely hepatology referral is essential for patients with high-risk features suggesting advanced fibrosis, cirrhosis, or diagnostic uncertainty. The following thresholds guide referral decisions from primary care to specialist hepatology services.

Indications for Hepatology Referral

Assessing for Cirrhosis Complications

Once cirrhosis is confirmed (F4), the following screening protocols should be initiated:

• HCC surveillance: 6-monthly abdominal ultrasound ± serum alpha-fetoprotein (AFP). MBS items: Ultrasound (Item 55056) and AFP (Item 66507). If ultrasound sensitivity is reduced (e.g., obesity, steatosis), consider contrast-enhanced CT or MRI.
• Variceal screening: Gastroscopy at diagnosis of cirrhosis. If no varices found and no decompensation, repeat in 2–3 years. If small varices, consider non-selective beta-blocker (carvedilol or propranolol).
• Assess for hepatic decompensation: Ascites (ultrasound), hepatic encephalopathy (clinical assessment), variceal bleeding, jaundice. Urgent hospital admission if decompensation is suspected.
• Calculate Child-Pugh and MELD scores to guide prognosis and transplant referral if indicated.

The following investigations are recommended in the assessment and monitoring of patients with NAFLD. Availability across Australian pathology and imaging services is indicated.

NAFLD pathophysiology is best understood through the "multiple-hit" model, which has superseded the older "two-hit" hypothesis. The progression from simple steatosis to NASH and fibrosis involves the interplay of metabolic, genetic, environmental, and gut-microbial factors.

Key Pathogenic Mechanisms

• Insulin resistance is the central driver: excess caloric intake and visceral adiposity lead to systemic and hepatic insulin resistance, promoting lipolysis in adipose tissue and delivery of free fatty acids (FFAs) to the liver.
• De novo lipogenesis (DNL): Hyperinsulinaemia and hyperglycaemia paradoxically stimulate hepatic DNL via SREBP-1c and ChREBP transcription factors, further increasing intrahepatic triglyceride content.
• Lipotoxicity: Saturated FFAs, diacylglycerols, and ceramides induce hepatocyte injury (lipotoxicity), endoplasmic reticulum stress, mitochondrial dysfunction, and activation of inflammatory pathways (NF-κB, JNK).
• Oxidative stress: Mitochondrial β-oxidation overload generates reactive oxygen species (ROS), causing lipid peroxidation and hepatocyte damage — the rationale for vitamin E therapy.
• Gut-liver axis: Altered gut microbiota (dysbiosis), increased intestinal permeability, and bacterial translocation activate hepatic Kupffer cells via toll-like receptors (TLR4, TLR9), driving inflammation and fibrogenesis.
• Hepatic stellate cell activation: The common pathway to fibrosis. Activated stellate cells produce extracellular matrix (collagen I, III), driven by TGF-β, PDGF, and other pro-fibrotic cytokines. Progressive collagen deposition leads to bridging fibrosis, architectural distortion, and eventually cirrhosis.
• Genetic modifiers: PNPLA3 (I148M variant), TM6SF2, and MBOAT7 polymorphisms significantly influence NAFLD susceptibility and progression. PNPLA3 I148M is particularly prevalent in certain populations, including some Indigenous Australian communities.

Disease Spectrum

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