Autoimmune Hepatitis

(Hepatology 2002;36:479-97)

DEFINITION:

Autoimmune Hepatitis (AIH) is an unresolving inflammation of liver, unknown cause:
- Characterized by interface hepatitis (histology), autoantibodies & hypergammaglobulinemia (serum)

Types of AIH:

Features	Type 1 (Classic)	Type 2	Type 3 (Least Established Form)
Predominant age	Adult (some children)	Child (girls > boys)	All ages ? if really a variant of Type 1 AIH
Auto Antibodies	ASMA^*	LKM1^ˆ	anti-SLA^*ˆ
	ANA, p-ANCA	Liver cytosol 1	ANA
	Anti-Actin
Organ-specific Ab	± (thyroid)	± (thyroid, parietal cells)	?
Autoantigen	Unknown	P450 2D6 (CYP2D6)	tRNP
HLA phenotype	B8, DR3, DR4	DR3, DR7	DR3
Fulminant onset	Possible (but rare)	Possible	Unknown
Concurrent disease	40% (see below)	32% (see below)	60% (see below)
Gamma globulin ↑	Yes	Slight	Moderate
Progress Cirrhosis	35%	80%	Probably
Steroid responsive	Yes	Yes	Yes
^anti-smooth muscle antibody, ^ˆanti-liver/kidney microsome type 1, ^ˆanti-soluble liver antigen

Overlap or Variant Syndrome:
- Autoimmune Hepatitis & PBC or PSC; Has high titers of AMA and cholestasis; See also Liver- PBC (Chapter 4.23)

EPIDEMIOLOGY:

F:M = 5:1, can occur at any age but typically before 4th decade; Represents <10% of all chronic hepatitis in the U.S. but 6% of transplants
Concurrent immunologic diseases can be present in patients, most common: autoimmune thyroiditis, ulcerative colitis, Graves, synovitis, RA

Others:

Celiac sprue
Coomb’s + hemolytic anemia
Cyroglobulinemia
Dermatitis herpetiformis

Erythema nodosum
Focal myositis
Gingivitis
Glomerulonephritis

ITP
Insulin DM
Iritis
Lichen planus

Myasthenia gravis
Neutropenia
Pericarditis
Peripheral neuropathy

Pernicious anemia
Pleuritis
Pyoderma gangrenosum

Sjogren’s
SLE
Urticaria
Vitiligo

ETIOLOGIES:

▪	Differential diagnosis	Diagnostic tests (See each corresponding diagnosis/chapter for details)
	Wilson’s	Copper studies: ↓ ceruloplasmin, ↓ serum copper, ↑ urinary copper
	PSC	Cholangiography: Focal biliary strictures; Liver biopsy: fibrous obliterate changes
	PBC	Auto Antibodies: AMA >1:40; Liver biopsy: florid duct lesion, ↑ hepatic copper
	Autoimmune cholangitis	Liver biopsy: cholangitis, ductopenia
	Chronic Hepatitis C	Viral labs: anti-HCV/RIBA positive, HCV RNA present
	Drug-induced Hepatitis	Clinical history: exposure to minocycline, nitrofurantoin, propylthiouracil, isoniazide, methyldopa
	Hemochromatosis	Genetics: C282Y, H63D mutations; Labs: ↑ Iron/Ferritin; Liver biopsy: iron overload, HII >1.9
	α1-AT	Phenotype: ZZ or MZ; Liver biopsy: hepatic inclusions, PAS +
	NASH	Clinical: obesity, DM, hyperlipidemia; Liver biopsy: macrosteatosis; U/S: hyperechogenicity

PATHOPHYSIOLOGY:

Pathogenic mechanisms unknown; Two theories: 1. Antibody-dependent cell-mediated form of cytotoxicity & 2. Cellular form of cytotoxicity
- Defect in modulation of B-cell production of IgG, creating an antigen-antibody complex on hepatocyte surface
- Autoantigen displayed on surface of antigen-presenting cells in association with HLA class II antigens
Multiple viruses thought to trigger AIH, including HAV, HBV, HCV; Currently, the definite diagnosis requires the exclusion of viral infections

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Aug 24, 2016 | Posted by drzezo in GASTROENTEROLOGY | Comments Off

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