25,729 articles
Hyperintensity
Hyperintensity: MRI term for tissue brighter than a comparison structure on a given sequence; covers T1/T2/FLAIR signal causes, white matter hyperintensities, and clinical significance.
Hyperkalaemia
Hyperkalaemia (hyperkalemia), elevated blood potassium above 5.5 mmol/l, caused by kidney disease, RAAS-inhibiting drugs, or excess intake; severe cases cause ECG changes, arrhythmia, and need calcium, insulin-glucose, salbutamol, dialysis, or binders.
Hyperkalemia
Hyperkalemia is abnormally high blood potassium, usually from impaired kidney excretion or drugs; defined as K+ ≥ 5.5 mmol/L (UKKA), graded mild to severe, treated with IV calcium, insulin-glucose, binders like SZC and patiromer, or dialysis.
Hyperkalemic periodic paralysis
Hyperkalemic periodic paralysis (Gamstorp disease, HyperPP) is a rare autosomal dominant SCN4A sodium channelopathy causing childhood-onset attacks of flaccid weakness with raised serum potassium, treated with carbohydrates, salbutamol, and diuretics.
Hyperkeratosis
Hyperkeratosis: thickening of the skin's stratum corneum from excess keratin or poor shedding; covers corns, calluses, keratosis pilaris, ichthyoses, psoriasis, actinic keratosis, and skin cancers.
Hyperkeratosis lenticularis perstans
Hyperkeratosis lenticularis perstans (Flegel disease, HLP, OMIM 144150) is a rare keratinization disorder with red-brown 1–5 mm scaly papules on the feet and lower legs, linked to SPTLC1 variants, lacking standard treatment.
Hyperlacrimation
Hyperlacrimation (ICD-11 9A10.3) is overflow of tears from excessive lacrimal gland secretion, caused by drugs, emotion, or trigeminal reflex irritation; distinct from epiphora, a drainage failure.
Hyperlexia
Hyperlexia: precocious, self-taught word reading far exceeding comprehension, usually with autism (about 84% of cases); coined by Silberberg and Silberberg in 1967; not a standalone DSM-5 diagnosis; three described types.
Hyperlipidemia
Hyperlipidemia (hypercholesterolemia, lipid disorder) is abnormally high blood lipids or lipoproteins. High LDL and triglycerides drive atherosclerosis; detected by lipid profile, treated with statins, ezetimibe, PCSK9 inhibitors.
Hypermagnesemia
Hypermagnesaemia (hypermagnesemia; ICD-10-CM E83.41) is an elevated serum magnesium level, defined above 2.6 mg/dL (1.05 mmol/L). Rare, usually caused by kidney failure with magnesium intake; causes reflex loss, hypotension, respiratory depression; treated with calcium gluconate, furosemide, or dialysis.
Hypermetabolism
Hypermetabolism is an abnormally fast metabolism causing weight loss and fatigue, seen after severe burns (REE 40-80% above normal, lasting up to two years), sepsis, eating disorder recovery, hyperthyroidism, and cancer.
Hypermethioninemia due to glycine N-methyltransferase deficiency
Hypermethioninemia due to glycine N-methyltransferase deficiency (GNMT deficiency, OMIM 606664) is a rare autosomal recessive disorder causing permanent marked hypermethioninemia with high AdoMet, normal AdoHcy, and mild liver enzyme elevations.
Hypermetropia
Hypermetropia, also called hyperopia or farsightedness, is a refractive error in which light focuses behind the retina with accommodation relaxed, blurring near vision; caused by short axial length or flat cornea, corrected with plus lenses.
Hypermobile Ehlers-Danlos syndrome
Hypermobile Ehlers-Danlos syndrome (hEDS), formerly EDS type III, is the most common Ehlers-Danlos type: a clinically diagnosed connective tissue disorder with joint hypermobility, no known gene, prevalence about 1:3,100, and updated criteria due December 2026.
Hypermobility (joints)
Joint hypermobility, also called being double-jointed, means joints with unusually large range of movement; assessed by the Beighton Score, it ranges from an asymptomatic trait to hypermobility spectrum disorders and hypermobile Ehlers-Danlos syndrome.
Hypernatremia
Hypernatremia is a serum sodium above 145 mmol/L from a water deficit relative to sodium, causing thirst and neurologic symptoms; treatment is controlled water replacement, with recent evidence favoring faster correction in admission-related and severe cases.
Hyperosmia
Hyperosmia is a quantitatively increased sense of smell, defined as an exceptionally high psychophysical olfactory test score (above the 90th percentile); distinct from olfactory intolerance, and often contradicted by objective testing showing hyposmia.
Hyperosmolar hyperglycemic state
Hyperosmolar hyperglycemic state (HHS), formerly hyperglycemic hyperosmolar nonketotic coma: a life-threatening type 2 diabetes emergency with glucose over 600 mg/dL, osmolality over 320 mOsm/kg, dehydration without ketoacidosis, and 5–16% mortality.
Hyperostosis corticalis generalisata
Hyperostosis corticalis generalisata, or van Buchem disease, is a rare autosomal recessive craniotubular hyperostosis caused by a 52-kb SOST regulatory deletion, causing skull and mandible thickening, cranial nerve palsies, and hearing loss, mainly in the Dutch population.
Hyperostosis cranialis interna
Hyperostosis cranialis interna (HCI, OMIM 144755) is an extremely rare autosomal dominant bone dysplasia, first described in 1990, causing endosteal hyperostosis of the calvaria and skull base with cranial nerve I, II, V, VII, and VIII entrapment; mapped to chromosome 8p21, SLC39A14 implicated.
Hyperostosis of skull
Hyperostosis of skull (ICD-10 M85.2), chiefly hyperostosis frontalis interna, benign nodular thickening of the frontal bone's inner table, common in postmenopausal women, usually incidental.
Hyperparathyroidism
Hyperparathyroidism is a condition that occurs when the parathyroid glands excessively secrete parathyroid hormone. It can manifest in primary, secondary, or tertiary forms, impacting calcium levels.
Hyperparathyroidism-jaw tumor syndrome
Hyperparathyroidism-jaw tumor syndrome (HPT-JT, OMIM 145001) is a rare autosomal dominant CDC73/parafibromin disorder causing primary hyperparathyroidism, jaw ossifying fibromas, renal and uterine tumors, and parathyroid carcinoma risk.
Hyperphenylalaninemia due to tetrahydrobiopterin deficiency
Hyperphenylalaninemia due to tetrahydrobiopterin deficiency (BH4 deficiency, atypical/malignant PKU): rare autosomal recessive disorders of GCH1, PTS, QDPR, or PCBD1 causing elevated phenylalanine plus dopamine and serotonin deficiency, treated with BH4, L-dopa, and 5-hydroxytryptophan.
Hyperpigmentation
Hyperpigmentation: excess melanin causing darker skin patches, mainly melasma and postinflammatory hyperpigmentation (PIH). Most common in Fitzpatrick phototypes III-VI; treated with sunscreen, hydroquinone, azelaic acid, retinoids, tranexamic acid, and procedures.
Hyperplasia
Hyperplasia is an increase in the number of cells in an organ or tissue, making it larger; the cells look normal and are not cancer, though some forms may become cancer.
Hyperplasia of appendix
Hyperplasia of appendix (ICD-11 DB11.1) is benign, reactive proliferation of appendiceal lymphoid tissue that can obstruct the lumen, mimic appendicitis, and be mistaken histologically for LAMN.
Hyperplastic duodenal polyp
Hyperplastic duodenal polyp (過形成性十二指腸ポリープ), ICD-11 DA53.0: a rare benign non-neoplastic duodenal epithelial growth, serrated microvesicular histology, often linked to H. pylori and gastroduodenal disease, treated by endoscopic resection.
Hyperpolarized MRI
Hyperpolarized MRI is a molecular imaging technique that boosts the carbon-13 MRI signal over 10,000-fold, letting scans map enzyme-driven metabolism, most often with injected pyruvate, in real time.
Hyperpolarized MRI of inhaled xenon
Hyperpolarized MRI of inhaled xenon is an MRI technique in which magnetically prepared xenon-129 gas is inhaled to map lung ventilation and gas exchange without ionizing radiation.