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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.
Hieraaetus
Hieraaetus (Kaup, 1844) is a genus of small booted eagles in Accipitridae, including the Booted, Little, Pygmy, Ayres's, and Wahlberg's Eagles plus the extinct Hieraaetus moorei; its split from Aquila remains debated among authorities.
Hieraaetus morphnoides
Hieraaetus morphnoides, the Little Eagle (Aquila morphnoides), is a small 45-55 cm Australian booted eagle with pale and dark morphs, rabbit-heavy diet, Vulnerable in ACT, NSW, SA, and Victoria.
Hieraaetus pennatus
Hieraaetus pennatus, the booted eagle (Aquila pennata), a small trans-Saharan migratory eagle breeding in southern Europe and wintering mainly in the Sahel; IUCN Least Concern, Spain holds about 70% of the European population.
Hieracium
Hieracium (hawkweeds) is a large Asteraceae genus of perennial herbs with yellow flowerheads, 4,614 accepted species, apomictic polyploids, and a split-off relative genus Pilosella; Mendel's later experimental plant.
HIF1A
HIF1A (HIF-1α) is the human gene at 14q23.2 encoding the oxygen-regulated alpha subunit of hypoxia-inducible factor 1, the master hypoxia transcription factor; PHD/VHL degradation, 2019 Nobel Prize, cancer and anemia therapies.
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 mobility group protein HMGN
HMGN (high mobility group N) proteins, formerly HMG-14/17, are a family of five vertebrate nucleosome-binding chromatin proteins (HMGN1-5) that modulate chromatin structure, epigenetics, development, and disease.
High potential iron-sulphur protein
High potential iron-sulphur protein (HiPIP), small bacterial electron-carrier protein with a 4Fe-4S cluster using the 3+/2+ redox couple at +50 to +450 mV, distinct from ferredoxins.
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-affinity choline transporter
High-affinity choline transporter (CHT1, SLC5A7): Na+- and Cl−-dependent presynaptic transporter that recycles choline for acetylcholine synthesis; rate-limiting step, HC-3-sensitive, mutated in DHMN7A and CMS20.
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-amylose cornstarch
High-amylose cornstarch (high-amylose maize starch, HAMS, amylomaize starch) is cornstarch with over 50 percent amylose versus 25 to 30 percent normally, from the ae (SBEIIb) mutation; a resistant starch source, GRAS-notified by Yale for oral rehydration solutions at 50 g/L (GRN 000615).
High-amylose cornstarch acetate
High-amylose cornstarch acetate (acetylated HAMS, CAS 9045-28-7) is a resistant-starch food ingredient, GRAS via FDA GRN 616 (Yale, 2016) for oral rehydration solutions at 50 g/L.
High-content screening
High-content screening is a cell biology method combining automated microscopy and image analysis to measure many features of individual cells, introduced in 1997 for drug discovery.
High-density lipoprotein
High-density lipoprotein (HDL), "good cholesterol": small dense plasma lipoproteins (4-13 nm, >1.063 g/ml) with apolipoprotein A-I that perform reverse cholesterol transport; HDL-C levels inversely track cardiovascular risk but raising them is not proven causal.
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.
High-flow oxygen therapy
High-flow oxygen therapy (HFNC) delivers heated, humidified blended air and oxygen through wide-bore nasal prongs at 20 to 70 L/min, used for hypoxemic respiratory failure, post-extubation support, and pediatric bronchiolitis.
High-flux dialysis
High-flux dialysis is a form of hemodialysis that uses dialyzer membranes with high water permeability and larger pores, allowing removal of middle-molecular-weight solutes such as beta-2-microglobulin beyond conventional low-flux clearance.
High-frequency audiometry
High-frequency audiometry, also called extended high-frequency (EHF) audiometry, is a diagnostic hearing test measuring the quietest audible tones above 8 kHz, up to 20 kHz.