A 46-year-old woman presents to her primary care provider for itching. She reports that she has always had dry skin but that the itching has gotten significantly worse over the last few years. The patient also endorses fatigue and dull abdominal pain. Her past medical history includes Hashimoto’s thyroiditis, mitral valve prolapse, and osteoarthritis. She takes levothyroxine and ibuprofen for pain in her knees. The patient drinks 2-3 beers per week. She has a 10 pack-year smoking history but quit 15 years ago. She denies any family history of cancer. On physical exam, her sclera are anicteric. Her abdomen is soft and tender to palpation in the right upper quadrant. Her bowel sounds are normal and hepatomegaly is present. A right upper quadrant ultrasound shows no evidence of extrahepatic biliary dilation. Laboratory studies are performed which reveal the following: Aspartate aminotransferase (AST): 76 U/L Alanine aminotransferase (ALT): 57 U/L Alkaline phosphatase: 574 U/L Total bilirubin: 1.6 mg/dL This patient is most likely to have which of the following additional findings?

Anti-neutrophil cytoplasmic antibodies

A 62-year-old woman with a history of hypertension, hyperlipidemia, and rheumatoid arthritis presents for evaluation of elevated serum liver chemistries. She has had three months of intense, unremitting itching. Current medications include chlorthalidone, atorvastatin, and ibuprofen. Physical exam is unremarkable. Laboratory studies show aspartate aminotransferase (AST) 42 units/L, alanine aminotransferase (ALT) 39 units/L, alkaline phosphatase 790 units/L, total bilirubin 0.8 mg/dL, and antimitochondrial antibody titer 1:80. What do you expect to see on liver biopsy?

Intrahepatic bile duct destruction

Bile plugging of hepatocytes and bile ducts

Intrahepatic and extra hepatic bile duct destruction

Lymphoplasmacytic and eosinophilic infiltration of portal tracts

A 31-year-old man presents to his primary care physician with shortness of breath. He states that he had a “cold” 2 weeks ago and since then has had a persistent cough and worsening shortness of breath. He denies fever, chills, chest pain, sore throat, or rhinorrhea. His medical history is significant for seasonal allergies. He uses fluticasone nasal spray. He had his tonsils removed when he was 8 years of age. His mother and maternal grandfather have cirrhosis, and his father has depression and hypertension. The patient endorses that he smokes tobacco socially on the weekends and uses marijuana daily. He drinks 1-2 beers after work with his co-workers most evenings. A chest radiograph shows hyperinflation of the lungs and hyperlucency. Routine labs are drawn, as shown below. Serum: Na+: 139 mEq/L Cl-: 105 mEq/L K+: 4.0 mEq/L HCO3-: 26 mEq/L Urea nitrogen: 15 mg/dL Glucose: 100 mg/dL Creatinine: 0.8 mg/dL Alkaline phosphatase: 98 U/L Aspartate aminotransferase (AST, GOT): 46 U/L Alanine aminotransferase (ALT, GPT): 49 U/L Pulmonary function tests are pending. Which of the following is most likely to confirm the patient’s diagnosis?

Enzyme-linked immunosorbent assay

Non-alcoholic fatty liver disease for USMLE Step 3: High-Yield Internal Medicine Lessons

NAFLD Fundamentals - A Fatty Situation

Definition: Hepatic steatosis (fat accumulation >5% by weight) without secondary causes like significant alcohol consumption.
Core Pathophysiology: Insulin resistance is the key driver, leading to:
- ↑ Peripheral lipolysis & FFA delivery to the liver.
- ↑ Hepatic de novo lipogenesis.
- ↓ VLDL export.
Disease Spectrum:
- NAFL (Simple Steatosis): Fat accumulation; generally benign.
- NASH (Nonalcoholic Steatohepatitis): Steatosis + inflammation + hepatocyte injury (e.g., ballooning). Carries risk of fibrosis progression.
- Cirrhosis & HCC: End-stage complications.

NAFLD progression: healthy liver to carcinoma

⭐ NAFLD is the hepatic manifestation of metabolic syndrome and the most common chronic liver disease in the United States.

Diagnosis - Catching the Culprit

Initial Clues: Often asymptomatic; discovered via incidental finding of elevated aminotransferases.
- AST/ALT ratio is typically < 1, distinguishing it from alcoholic liver disease (where the ratio is often > 2).
Non-Invasive Assessment: First, rule out other liver disease causes (viral, alcohol, autoimmune).
- Imaging: Ultrasound is the primary screening tool, revealing hepatic steatosis (a bright, echogenic liver).
- Fibrosis Scoring: Use tools like the FIB-4 or NAFLD Fibrosis Score to estimate fibrosis risk using patient age, AST, ALT, and platelet count.
- Elastography: Transient elastography (FibroScan) or MRE can quantify liver stiffness to assess fibrosis non-invasively.
Gold Standard:
- Liver Biopsy: The definitive test to differentiate simple steatosis (NAFL) from NASH (inflammation, ballooning) and to accurately stage fibrosis. Reserved for cases where the diagnosis is uncertain or there's a high risk of advanced fibrosis.

⭐ The diagnosis of NAFLD is fundamentally a diagnosis of exclusion. A thorough workup to rule out other etiologies of chronic liver disease is a critical first step.

Ultrasound: Normal vs. Grade 1 Fatty Liver

Management - The Great Reversal

Cornerstone: Lifestyle Modification
- Weight Loss: The most effective intervention. Target >7-10% of body weight to resolve steatosis and inflammation.
- Diet: Mediterranean diet is preferred. Crucially, ↓ intake of high-fructose corn syrup.
- Exercise: 150-200 mins/week of moderate-intensity aerobic activity.
- Control comorbidities: Aggressively manage diabetes, hypertension, and dyslipidemia.
Pharmacotherapy (for biopsy-proven NASH & fibrosis ≥ F2)
- Vitamin E (Tocopherol): An antioxidant that improves liver histology.
- Pioglitazone: Insulin sensitizer, improves steatosis and inflammation.

NAFLD: Healthy Liver vs. NAFL vs. NASH vs. Cirrhosis

⭐ For patients with co-existing Type 2 Diabetes, Pioglitazone is a key consideration as it addresses both insulin resistance and liver inflammation in NASH.

High‑Yield Points - ⚡ Biggest Takeaways

NAFLD is a spectrum from simple steatosis to NASH, which can progress to cirrhosis and HCC.

It's the liver manifestation of metabolic syndrome, driven by insulin resistance.

Most patients are asymptomatic with incidentally elevated liver enzymes.

Lab hallmark is an AST/ALT ratio < 1, unlike alcoholic liver disease.

Liver biopsy is the gold standard to diagnose NASH and stage fibrosis.

Management cornerstone is weight loss and managing metabolic comorbidities.

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Non-alcoholic fatty liver disease