Human health and medicine

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.

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.

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.

Hepatomegaly or splenomegaly

Hepatomegaly or splenomegaly (hepatosplenomegaly, ICD-11 ME10.0) is abnormal enlargement of the liver or spleen, almost always secondary to liver disease, malignancy, infection, or storage disease, confirmed by ultrasound.

Hepatoportoenterostomy

Hepatoportoenterostomy, also called the Kasai procedure or hepatic portoenterostomy, is an operation that restores bile drainage in infants with biliary atresia by joining a jejunal loop to the liver's porta hepatis.

Hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS): hypoxemia from intrapulmonary vascular dilatations in liver disease or portal hypertension; diagnosed by A-a gradient and contrast echocardiography; cured only by liver transplantation.

Hepatorenal syndrome

Hepatorenal syndrome (HRS) is a form of kidney failure in people with advanced liver disease, most often cirrhosis, in which healthy kidneys stop filtering blood due to severe vessel constriction.

Hepatosplenic T-cell lymphoma

Hepatosplenic T-cell lymphoma (HSTCL), historically hepatosplenic gamma/delta T-cell lymphoma, is a rare aggressive peripheral T-cell lymphoma of the spleen, liver, and bone marrow, usually γδ TCR-positive, with isochromosome 7q, STAT/JAK mutations, and median survival near 12 months.

Hepatotoxicity

Hepatotoxicity, or drug-induced liver injury (DILI), is liver damage from drugs, herbals, or supplements; idiosyncratic DILI causes up to 13% of US acute liver failure and is diagnosed by RUCAM, RECAM, and exclusion.

HEPCPR trial

The HEPCPR trial was a randomized study of peginterferon alfa-2a plus ribavirin in 41 HCV/HIV-coinfected patients who had not responded to prior interferon therapy, reporting an intent-to-treat SVR of 21.9%.

Heptabarbital

Heptabarbital (Medomin, Heptabarb, CAS 509-86-4) is a withdrawn cycloheptenyl-ethyl barbiturate hypnotic, ATC N05CA11, DDD 0.2 g oral, half-life about 7.6 h, formerly marketed by Geigy for insomnia.

HER2 testing

HER2 testing is the laboratory measurement of HER2 protein overexpression or ERBB2 gene amplification in tumors, using immunohistochemistry and in situ hybridization, to guide anti-HER2 therapy.

HER2/CEP17 FISH ratio assay

The HER2/CEP17 FISH ratio assay is a dual-probe fluorescence in situ hybridization test measuring HER2 gene signals against chromosome 17 signals to determine breast cancer eligibility for anti-HER2 therapy.

HERA trial

HERA (HERceptin Adjuvant, BIG 1-01, NCT00045032) trial: phase 3 study of 5,102 women with HER2-positive early breast cancer randomized to 1 or 2 years of adjuvant trastuzumab versus observation after chemotherapy; 1 year improved survival, 2 years added none.

Herbal medicine

Herbal medicine, also known as phytotherapy, is healing that uses plant parts such as roots, leaves, flowers, and seeds to maintain health and treat illness.

Herd immunity

Herd immunity, also called community or indirect protection, occurs when enough of a population is immune, by vaccination or infection, that transmission chains break. Threshold is 1 − 1/R0; measles needs about 95% coverage, polio about 80%.

Hereditary amyloidosis with primary renal involvement

Hereditary amyloidosis with primary renal involvement (familial renal amyloidosis, Ostertag type, ORPHA:85450) is a group of rare autosomal dominant amyloidoses, subtypes AApoAI, AApoAII, AFib, and ALys, causing proteinuria and progressive renal failure.

Hereditary angioedema with C1Inh deficiency

Hereditary angioedema with C1 inhibitor deficiency (HAE-C1-INH, types I and II) is a SERPING1-related genetic disorder causing bradykinin-mediated swelling attacks, treated with C1-INH concentrate, icatibant, ecallantide, or sebetralstat.

Oct 20, 2026

Hereditary angioedema with normal C1Inh

Hereditary angioedema with normal C1 inhibitor (HAE-nC1INH), formerly HAE type III, is a bradykinin-mediated hereditary angioedema first described in 2000, with normal C1INH levels, genetic subtypes HAE-FXII, PLG, KNG1, ANGPT1, MYOF, HS3ST6, and expert-opinion-based treatment.

Hereditary arterial and articular multiple calcification syndrome

Hereditary arterial and articular multiple calcification syndrome (CALJA, ACDC) is an autosomal recessive NT5E (CD73 deficiency) disorder causing adult-onset calcification of lower-limb arteries and hand and foot joint capsules, with claudication and early arthritis.

Hereditary atrial fibrillation

Hereditary atrial fibrillation, also called familial or early-onset AF, is atrial fibrillation driven by inherited variants, from monogenic KCNQ1, SCN5A, TTN, and LMNA mutations to polygenic risk, with 2023 guideline Class IIb genetic testing for onset before age 45.

Hereditary ATTR amyloidosis

Hereditary ATTR amyloidosis (ATTRv, hATTR) is a rare autosomal dominant TTR gene disease causing misfolded transthyretin amyloid deposits in nerves and heart, treated with stabilizers and gene-silencing drugs.