3.10 Inherited, Autoimmune & Drug-Induced Liver Disease

1. Gilbert Syndrome: The Benign Distractor

Gilbert syndrome is a common, benign, inherited reduction in UDP-glucuronosyltransferase activity. It matters on the exam because it is the correct answer whenever a well patient has an isolated bilirubin elevation and the tempting wrong answer is an expensive hepatology workup.

The signature is precise:

• Unconjugated (indirect) hyperbilirubinemia, usually below 3–4 mg/dL
• Normal aminotransferases, alkaline phosphatase and albumin
• No hemolysis — normal haptoglobin, reticulocyte count and lactate dehydrogenase
• Bilirubin rises with fasting, dehydration, intercurrent illness, stress or exertion, which is why it is so often discovered during an unrelated admission

No treatment, no imaging and no biopsy are needed. One practical consequence: Gilbert syndrome impairs glucuronidation of some drugs, notably irinotecan, increasing toxicity.

The differential for unconjugated hyperbilirubinemia is short — Gilbert syndrome, hemolysis, and resorption of a large hematoma. A conjugated (direct) elevation is never Gilbert syndrome and always signals hepatocellular or cholestatic disease.

2. Hereditary Hemochromatosis

Autosomal recessive iron overload, most often from HFE C282Y homozygosity, with highest prevalence in people of northern European ancestry.

Screening sequence:

1. Transferrin saturation — the most sensitive early marker; a value at or above roughly 45% is abnormal
2. Ferritin — reflects total body stores but is also an acute-phase reactant
3. HFE genotyping when both are elevated
4. MRI quantification of hepatic iron; biopsy is now rarely required

Organ involvement produces the classic multisystem picture: cirrhosis and hepatocellular carcinoma, diabetes (bronze diabetes), skin hyperpigmentation, restrictive or dilated cardiomyopathy, hypogonadotropic hypogonadism, and a distinctive arthropathy of the second and third metacarpophalangeal joints — the blueprint lists arthropathy of hemochromatosis separately under Rheumatology.

Treatment is therapeutic phlebotomy, continued until ferritin reaches the low-normal range and then maintained. Iron chelation is reserved for those who cannot tolerate phlebotomy, typically because of anemia. Patients should avoid iron and vitamin C supplements and uncooked shellfish (Vibrio vulnificus thrives in iron-replete hosts). Phlebotomy prevents cirrhosis if started early but does not reverse established cirrhosis, and those patients still require hepatocellular carcinoma surveillance.

3. Wilson Disease

Autosomal recessive impairment of biliary copper excretion from ATP7B mutation. Presentation is typically between the ages of 5 and 40, and the rule worth memorizing is: consider Wilson disease in any patient under 40 with unexplained liver disease.

Screening: low serum ceruloplasmin with elevated 24-hour urinary copper. Ceruloplasmin is an acute-phase reactant and may be falsely normal during inflammation, so a normal value does not exclude the diagnosis.

The fulminant presentation has a distinctive laboratory fingerprint, frequently tested: a disproportionately low alkaline phosphatase relative to total bilirubin, with Coombs-negative hemolysis and only modest aminotransferase elevation. Fulminant Wilson disease is not salvageable medically and requires urgent transplant evaluation.

Chronic treatment uses chelation with penicillamine or trientine, or zinc to block intestinal copper absorption, plus dietary copper restriction.

4. Alpha-1 Antitrypsin Deficiency

Misfolded protein accumulates in hepatocytes (causing liver disease) while circulating levels are insufficient to protect the lung (causing panacinar, basilar-predominant emphysema). The paired presentation — early emphysema in a minimal or non-smoker plus unexplained liver disease — should trigger measurement of the alpha-1 antitrypsin level and phenotyping. Liver biopsy shows periodic acid-Schiff-positive, diastase-resistant globules. Augmentation therapy addresses the lung disease only; it does not help the liver, because the hepatic injury results from intracellular accumulation rather than deficiency.

5. Autoimmune Hepatitis

A chronic immune-mediated hepatitis that most often affects women and frequently coexists with other autoimmune disease. It may present indolently, as an acute hepatitis, or as established cirrhosis.

Typical laboratory profile:

• Hepatocellular pattern with aminotransferases often several hundred to over a thousand
• Elevated IgG / polyclonal gammopathy — a highly characteristic feature
• Type 1: antinuclear antibody and/or anti-smooth muscle antibody
• Type 2: anti-liver-kidney microsomal type 1 antibody, typically younger patients

Liver biopsy shows interface hepatitis with a plasma-cell-rich infiltrate. Treatment is prednisone, with azathioprine added as a steroid-sparing agent; thiopurine methyltransferase activity should be assessed before starting azathioprine. Untreated disease progresses to cirrhosis, so a positive antibody with active hepatitis should not simply be observed.

Overlap syndromes with primary biliary cholangitis or primary sclerosing cholangitis occur and are suggested by a mixed hepatocellular and cholestatic enzyme pattern.

6. Drug-Induced Liver Injury

The blueprint lists drug-induced liver disease other than acetaminophen separately, precisely because acetaminophen behaves differently from idiosyncratic injury.

Acetaminophen injury is the most common cause of acute liver failure in the United States. It occurs not only after intentional overdose but with therapeutic misadventure — repeated supratherapeutic dosing in a patient who is fasting, malnourished or consuming alcohol, all of which deplete glutathione and induce CYP2E1. N-acetylcysteine should be given when injury is suspected; it is most effective early but retains benefit late.

High-yield idiosyncratic offenders: isoniazid, amoxicillin-clavulanate (the most common cause of drug-induced cholestatic injury, often with delayed onset after the course is finished), nitrofurantoin, minocycline, methotrexate, azole antifungals, anabolic steroids and herbal or dietary supplements — green tea extract, anabolic-containing bodybuilding products and kava among them. Always ask about supplements; patients rarely volunteer them as medications.

Hy's law identifies a high risk of fatal outcome: hepatocellular injury with aminotransferases above three times the upper limit of normal and bilirubin above twice the upper limit of normal, without biliary obstruction.

7. Budd-Chiari Syndrome

Hepatic venous outflow obstruction. The classic triad is abdominal pain, ascites and hepatomegaly, with a paradoxically high serum-ascites albumin gradient but a high ascitic protein, distinguishing it from cirrhotic ascites.

Diagnosis is by Doppler ultrasonography of the hepatic veins. Because roughly 80% of cases have an identifiable prothrombotic cause, the finding obliges a hypercoagulability evaluation — myeloproliferative neoplasms including the JAK2 V617F mutation (the single most common association), paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, oral contraceptive use and pregnancy. Management is anticoagulation, treatment of the underlying disorder, and escalation to angioplasty, transjugular intrahepatic portosystemic shunt or transplantation.

8. Acute Liver Failure and Transplantation

Acute liver failure is coagulopathy (INR ≥ 1.5) with any degree of encephalopathy in a patient without pre-existing cirrhosis. The encephalopathy is what separates acute liver failure from severe acute hepatitis, and it mandates immediate transfer to a transplant center.

Causes in approximate order: acetaminophen, idiosyncratic drug injury, viral hepatitis, autoimmune hepatitis, Wilson disease, Budd-Chiari syndrome, and ischemic or shock liver.

N-acetylcysteine improves transplant-free survival in non-acetaminophen acute liver failure as well as in acetaminophen toxicity — a point that is frequently missed. Cerebral edema is the leading cause of death, so intracranial pressure management and avoidance of hypotonic fluids matter. Prophylactic correction of coagulopathy with plasma is generally avoided because it obscures the INR trend used to assess prognosis and transplant need.