Life and health

Hepaticojejunostomy

Hepaticojejunostomy, also called the Rodney Smith operation when performed with transhepatic intubation, is a surgical operation connecting the hepatic bile duct to a Roux-en-Y jejunal limb to bypass strictures and repair bile duct injuries.

Hepatitis

Hepatitis: inflammation of the liver, mainly from viruses A through E. HBV (240 million chronic cases) and HCV (47 million) cause 95% of deaths; 1.3 million died in 2024; vaccines prevent A and B, drugs cure C.

Hepatitis A

Hepatitis A is an acute liver inflammation caused by the hepatitis A virus (HAV), a fecal-orally transmitted picornavirus. Distinguished from hepatitis B by its 28-day incubation, lack of chronicity, and preventability with vaccines licensed since 1995.

Hepatitis A virus internal ribosome entry site (IRES)

The hepatitis A virus (HAV) IRES, the type III picornavirus IRES, is a structured RNA in the 735 nt 5'UTR that drives cap-independent translation but uniquely requires intact eIF4G and eIF4E, is inefficient, and does not let HAV shut off host translation.

Hepatitis B

Hepatitis B, caused by the hepatitis B virus (HBV), a hepadnavirus, is a vaccine-preventable liver infection; 240 million chronic cases and 1.1 million deaths in 2024, vaccine since 1982.

Hepatitis B vaccine

Hepatitis B vaccine: recombinant HBsAg vaccine preventing HBV infection and liver cancer; first plasma-derived version 1981, recombinant 1986; birth dose recommended by WHO; US ACIP ended universal birth dose 2025.

Hepatitis B virus

Hepatitis B virus (HBV) is an enveloped DNA virus of the Hepadnaviridae family that infects the liver, chronically affecting 240 million people and preventable by vaccine.

Hepatitis C

Hepatitis C, liver inflammation caused by the bloodborne hepatitis C virus (HCV), formerly non-A, non-B hepatitis, identified in 1989; 47 million chronic infections, no vaccine, but direct-acting antivirals cure over 95% in 8–12 weeks.

Hepatitis C and HIV coinfection

HIV/HCV coinfection, simultaneous infection with HIV and hepatitis C virus, affects about 21% of US adults with HIV and up to 82% of those who inject drugs; HIV accelerates liver fibrosis, but direct-acting antivirals cure HCV in over 94% of coinfected patients.

Hepatitis C virus

Hepatitis C virus (HCV), bloodborne enveloped RNA virus causing liver disease; discovered 1989 (Nobel 2020); 47 million chronic infections; DAAs cure over 95%, no vaccine.

Hepatitis core antigen

Hepatitis core antigen (HBcAg) is the HBV capsid protein, 183–185 amino acids, forming T=4 capsids of 120 dimers; anti-HBc aids diagnosis and HBcrAg (HBcAg plus HBeAg and p22cr) serves as a low-cost serum marker of HBV replication and cccDNA.

Hepatitis D

Hepatitis D (hepatitis delta virus, HDV) is a defective circular RNA satellite virus causing liver inflammation only in people with hepatitis B; ~12 million affected, IARC-classified carcinogenic, treated with interferon and bulevirtide.

Hepatitis delta antigen (HDAg) domain

HDAg domain (IPR037517, PROSITE PS51838): conserved domain of hepatitis delta antigen, the sole HDV protein, and human NELF-A; coiled-coil oligomerization core, NLS, RNA-binding and RNAPII-binding regions.

Hepatitis Delta Virus

Hepatitis delta virus (HDV), also called hepatitis D virus or delta agent, is a defective circular RNA satellite virus of hepatitis B virus causing the most severe chronic viral hepatitis, infecting an estimated 12 million people, treated with bulevirtide and interferon.

Hepatitis due to Toxoplasma gondii

Toxoplasmic hepatitis is rare liver inflammation caused by Toxoplasma gondii, the protozoan of toxoplasmosis; it occurs in acute infection of healthy people, disseminated AIDS disease, and is associated with chronic liver disease (odds ratio 2.7).

Hepatitis E

Hepatitis E, caused by the hepatitis E virus (HEV), is a fecal-orally transmitted liver inflammation with ~20 million yearly infections, high pregnancy mortality, and one licensed vaccine, Hecolin (HEV 239).

Hepatitis serology

Hepatitis serology is blood-based testing for hepatitis virus antigens and antibodies, used to diagnose infection, stage it as acute or chronic, and establish immunity, complemented by nucleic acid testing.

Hepatobiliary scintigraphy

Hepatobiliary scintigraphy, also called cholescintigraphy or HIDA, is a nuclear medicine scan that tracks an injected radioactive tracer through the liver and bile system, chiefly to diagnose acute cholecystitis.

Oct 20, 2026

Hepatoblast

A hepatoblast is a bipotent progenitor cell of the fetal liver that gives rise to hepatocytes and cholangiocytes, and is distinct from the adult hepatic stem cell.

Hepatoblastoma

Hepatoblastoma (HB), childhood embryonic liver cancer, most common pediatric primary malignant liver tumor, ages 0-4, Wnt/CTNNB1-driven, treated with cisplatin chemotherapy, resection, or liver transplant; survival now about 80%.

Hepatocellular adenoma

Hepatocellular adenoma (HCA, liver cell adenoma) is a rare benign hepatocellular liver tumor of non-cirrhotic liver, mainly in young women on oral contraceptives; molecular subtypes (HNF1A, inflammatory, beta-catenin, sonic hedgehog) determine hemorrhage and HCC transformation risk.

Hepatocellular ballooning

Hepatocellular ballooning is a liver biopsy finding in which injured hepatocytes become markedly swollen with rarefied cytoplasm from keratin 8/18 cytoskeleton collapse, a required feature for diagnosing steatohepatitis.

Hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the main primary liver cancer (80-90% of cases), arises mostly in cirrhosis from viral hepatitis, alcohol, or MASLD; treated by resection, transplant, ablation, TACE, and immunotherapy.

Hepatocyte

Hepatocyte: the liver cell, main parenchymal cell of the liver (~80% of liver cells). Multipolar epithelial cell with bile canaliculi, three perfusion zones, plasma protein synthesis, and drug metabolism; isolated by collagenase perfusion since 1967.

Hepatocyte growth factor

Hepatocyte growth factor (HGF, hepatotropin, scatter factor) is a 728-amino-acid cytokine ligand of the Met receptor tyrosine kinase, discovered in 1984, essential for liver development and regeneration, and a major target in cancer therapy.

Hepatocyte nuclear factor 1

Hepatocyte nuclear factor 1 (HNF-1, HNF1) is a homeodomain transcription factor that controls liver proteins such as albumin and works in the liver, pancreas, kidney, and intestine.

Hepatoerythropoietic porphyria

Hepatoerythropoietic porphyria (HEP), also called UROD-related hepatoerythropoietic porphyria, is an ultra-rare autosomal recessive porphyria from biallelic UROD variants, causing childhood-onset blistering photosensitivity, hypertrichosis, scarring, red urine, and anemia, with fewer than 100 reported cases.

Hepatology

Hepatology is the medical specialty covering liver, biliary, and pancreatic disease, from viral hepatitis and MASLD to cirrhosis and transplantation. Key facts: AASLD founded 1950; ABIM transplant hepatology certification 2006; liver biopsy still proves NASH.

Hepatomegaly

Hepatomegaly, or enlarged liver, is abnormal liver enlargement from hepatitis, fatty liver disease, alcohol-related disease, heart congestion, or cancer; detected by percussion span or imaging and treated by addressing the cause.