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Heyde's syndrome
Heyde's syndrome is the triad of aortic stenosis, gastrointestinal bleeding from angiodysplasia, and acquired von Willebrand syndrome caused by shear-induced loss of high-molecular-weight vWF multimers; aortic valve replacement resolves most cases.
HFB1011 (anti-CCR8 antibody)
HFB1011 (HFB101110) is HiFiBiO Therapeutics' humanized anti-CCR8 monoclonal antibody that depletes tumor-infiltrating regulatory T cells via ADCC and blocks CCL1 binding; licensed to FibroGen in 2021, returned to HiFiBiO in 2025.
HGH Fragment 176–191
HGH Fragment 176-191 (hGH 176-191, Frag 176-191) is the synthetic 16-amino-acid C-terminal fragment of human growth hormone, sequence FLRIVQCRSVEGSCGF, studied for lipolytic activity; distinct from AOD-9604, with no human trials and no regulatory approval.
Hh blood group
Hh blood group (ISBT H, 018): system based on the H antigen made by FUT1 and FUT2. Homozygous hh gives the rare Bombay (Oh) phenotype, anti-H, transfusable only with Bombay blood; para-Bombay is the weak-H variant.
HH2853 (EZH1/2 inhibitor)
HH2853 (HH 2853, HH-2853) is an oral dual EZH1/EZH2 inhibitor from Haihe Biopharma that blocks H3K27 methylation; phase I/II trials show responses in PTCL and epithelioid sarcoma.
Hiatal hernia
Hiatal hernia (hiatus hernia): the stomach's top bulges through the diaphragm's esophageal hiatus. Very common with age (70% over 70); type 1 sliding form is 95% of cases; treated with PPIs or laparoscopic fundoplication.
Hiatal hernia repair
Hiatal hernia repair is surgery that pulls a stomach herniated through the diaphragm back into the abdomen, narrows the hiatus, and usually adds a fundoplication to restore the antireflux barrier.
Hib vaccine
Hib vaccine, or Haemophilus influenzae type b conjugate vaccine, protects infants against Hib meningitis. Conjugate vaccines licensed since 1987 cut US Hib infection by over 99%; given at 2, 4, 6, and 12–15 months.
HIBIC-NSCLC study
HIBIC-NSCLC (NCT06518018) is a retrospective propensity score-matched study at Neijiang Second People's Hospital testing HDR brachytherapy plus immune checkpoint inhibitors and docetaxel as second-line treatment for advanced NSCLC, reporting improved OS and PFS.
Hiccup
Hiccup (singultus, hiccough): involuntary diaphragm spasm with sudden vocal cord closure producing the "hic" sound. Usually self-limiting; hiccups over 48 hours may indicate GERD, stroke, or tumors; chlorpromazine is the only FDA-approved drug.
Hick's law
Hick's law, or the Hick–Hyman law, states that choice reaction time rises linearly with the logarithm of the number of alternatives (RT = a + b log2 n). Established by W. E. Hick (1952) and Ray Hyman (1953) from information theory, with roots in Merkel's 1885 experiments; a foundational but debated principle of interface design.
Hickman line
Hickman line, also called Hickman catheter, a tunneled silicone central venous catheter with a Dacron cuff, invented by Robert Hickman in 1979 by enlarging the Broviac catheter for bone marrow transplantation; used for chemotherapy, parenteral nutrition, and blood sampling.
HiCM-188 (iPSC-derived cardiomyocytes)
HiCM-188 (人iPSC来源心肌细胞注射液) is HELP Therapeutics' allogeneic iPSC-derived cardiomyocyte injection for severe ischemic heart failure, given during CABG; first iPSC-CM therapy with IND clearance in both China and the US, with HEAL-CHF results published in Nature Medicine.
HIDEA syndrome
HIDEA syndrome is a rare autosomal recessive neurodevelopmental disorder caused by P4HTM gene variants, first described in 2014 in Finland; fewer than 50 patients worldwide show hypotonia, intellectual disability, and epilepsy.
Hidradenitis suppurativa
Hidradenitis suppurativa (acne inversa) is a chronic inflammatory skin disease causing painful nodules, abscesses, tunnels, and scarring in armpits, groin, and other skin-fold areas, typically starting after puberty, more common in women, and treated with antibiotics, biologics such as adalimumab, and surgery.
Hidrocystoma
Hidrocystoma (cyst of Moll, apocrine or eccrine hidrocystoma) is a benign cystic sweat gland lesion of the head and neck, especially eyelids; eccrine lesions grow in hot weather, apocrine ones do not, and excision is the main treatment.
Hidrotic ectodermal dysplasia
Hidrotic ectodermal dysplasia, or Clouston syndrome (HED2), an autosomal dominant GJB6/connexin 30 disorder with nail dystrophy, alopecia, and palmoplantar hyperkeratosis but normal teeth and sweating.
HIFU ablation
HIFU ablation is a noninvasive treatment using focused high-intensity ultrasound beams to heat and destroy targeted tissue, such as tumors, guided by MRI or ultrasound.
Higenamine hydrochloride
Higenamine hydrochloride (盐酸去甲乌药碱), also called norcoclaurine hydrochloride, is a benzylisoquinoline β-adrenoceptor agonist from aconite, approved in China in April 2026 as the first class 1 innovative cardiac stress agent for myocardial perfusion imaging.
High affinity haemoglobin
High affinity hemoglobin is an inherited autosomal dominant variant, first described in 1966, in which oxygen is loaded normally but released poorly, causing tissue hypoxia and erythrocytosis.
High anion gap metabolic acidosis
Anion gap metabolic acidosis: metabolic acidosis with elevated serum anion gap (AG = Na − (Cl + HCO3), normally 8–16 mmol/L) from unmeasured organic anions such as lactate, ketoacids, and toxic alcohols.
High bone mass osteogenesis imperfecta
High bone mass osteogenesis imperfecta (ORPHA:314029), a rare autosomal dominant OI subtype from BMP1 or procollagen C-propeptide cleavage-site variants, causes childhood fractures despite increased bone mineral density.
High pressure primary open-angle glaucoma
High pressure primary open-angle glaucoma (high-tension glaucoma, ICD-11 9C61.02): POAG with IOP above 21 mmHg, open angle, reduced trabecular outflow, lamina cribrosa damage, and IOP-lowering treatment goals of 20-30% reduction.
High- and low-affinity hemoglobin variants
High- and low-affinity hemoglobin variants are inherited mutations in alpha- or beta-globin genes that change how tightly hemoglobin binds oxygen, causing erythrocytosis or cyanosis; most run a benign course.
High-altitude cerebral edema
High-altitude cerebral edema (HACE), the severe end-stage form of acute mountain sickness, is hypoxia-induced brain swelling with ataxia and altered mental status above roughly 4,000 m, treated by descent, oxygen, and dexamethasone.
High-altitude pulmonary edema
High-altitude pulmonary edema (HAPE) is noncardiogenic lung edema after rapid ascent above about 2,500 m, driven by exaggerated hypoxic pulmonary vasoconstriction; treated by descent, oxygen, and nifedipine.
High-dose interleukin-2 therapy
High-dose interleukin-2 therapy, also known as aldesleukin or Proleukin, is an immunotherapy that activates T cells against metastatic renal cell carcinoma and melanoma, approved in 1992.
High-dose-rate brachytherapy
High-dose-rate (HDR) brachytherapy is a radiation therapy technique delivering short, intense doses from a radioactive iridium-192 source placed inside or next to the tumor, used mainly for cervix and prostate cancer.
High-Energy Radiotherapy
High-energy radiotherapy (megavolt radiotherapy) is cancer treatment with megavoltage-or-higher ionizing radiation: gamma rays, x-rays, electrons, protons, and heavy ions, delivered by cobalt-60 units and linacs since the 1950s.
High-Fat Diet
High-fat diet: consumption of excessive dietary fats (MeSH D059305). Covers habitual high-fat intake limited by WHO guidance and deliberate ketogenic regimens (4:1 ratio, under 50 g carbohydrate daily) used for epilepsy since the 1920s.