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Hypochondroplasia
Hypochondroplasia is an uncommon hereditary disorder of skeletal development caused by mutations in the FGFR3 gene, producing short stature with disproportionately short limbs, typically milder than achondroplasia.
Hypochromic anemia
Hypochromic anemia (historically chlorosis): anemia with abnormally low red cell hemoglobin concentration (MCHC < 32 g/dL), usually microcytic; most often iron deficiency, but thalassemia, sideroblastic anemia, and lead poisoning must be distinguished by iron studies.
Hypocomplementemic urticarial vasculitis
Hypocomplementemic urticarial vasculitis (HUV, McDuffie syndrome, HUVS) is a rare anti-C1q immune complex small vessel vasculitis with chronic urticaria, low C1q/C3/C4, arthritis, ocular, renal, and pulmonary involvement.
Hypocrea
Hypocrea Fr. (1825), type genus of Hypocreaceae, is the sexual teleomorph genus of Trichoderma molds, typified by H. rufa; since the 2011 one-fungus-one-name rules Trichoderma (1794) is the accepted name.
Hypocreales
Hypocreales (Lindau, 1897) is an order of Sordariomycetes fungi in Ascomycota, parasitic on plants, insects, or fungi, or saprotrophic; includes Beauveria, Cordyceps, Fusarium, and Trichoderma, spanning plant pathogens, biocontrol agents, antibiotics, and mycotoxins.
Hypodermic needle
Hypodermic needle: hollow stainless steel tube on a Luer hub for injecting medication or aspirating fluid below the skin; FDA Class II (880.5570), ISO 7864 single-use standard, sizes 0.18-3.4 mm, invented from Rynd's 1844 needle and Wood/Pravaz 1853 syringes.
Hypodermoclysis
Hypodermoclysis, or subcutaneous fluid infusion, rehydrates mildly to moderately dehydrated patients, especially older adults and palliative care patients, when venous access is difficult; about 3 L daily at two sites.
Hypodontia
Hypodontia, also called tooth agenesis or partial anodontia, is the developmental absence of one or more teeth, affecting 2–8% of people for permanent teeth; linked to PAX9, MSX1, AXIN2, EDA, and WNT10A mutations and treated by orthodontics, bridges, or implants.
Hypodontia-dysplasia of nails syndrome
Hypodontia-dysplasia of nails syndrome, also known as Witkop syndrome or tooth and nail syndrome, is a rare autosomal dominant ectodermal dysplasia causing missing permanent teeth and dysplastic nails, first described in 1965.
Hypogastric plexus
The hypogastric plexus is a network of nerve fibers in the pelvis, divided into superior and inferior parts, that supplies autonomic innervation to the bladder, rectum, and reproductive organs.
Hypoglossal nerve
Hypoglossal nerve (cranial nerve XII): pure motor nerve from the medulla's hypoglossal nucleus, exiting via the hypoglossal canal, supplying all tongue muscles except palatoglossus; lesions deviate the tongue toward the lesion.
Hypoglossal nerve stimulation
Hypoglossal nerve stimulation is a surgically implanted therapy that moves the tongue forward during sleep to treat obstructive sleep apnea in adults who cannot use CPAP.
Hypoglossia-hypodactyly syndrome
Hypoglossia-hypodactyly syndrome, also called Hanhart syndrome or aglossia-adactylia, is a rare congenital condition combining an underdeveloped tongue, a small lower jaw, and limb defects ranging from missing finger and toe bones to absent digits or limbs.
Hypoglycaemia unawareness
Hypoglycaemia unawareness, or impaired awareness of hypoglycaemia, is loss of autonomic warning symptoms of low blood glucose in insulin-treated diabetes, driven by recurrent hypoglycaemia via HAAF, raising severe hypoglycaemia risk about six-fold.
Hypoglycemia
Hypoglycemia, also known as low blood sugar or glucopenia, is a blood glucose concentration below 70 mg/dL (3.9 mmol/L); it is common in people treated with insulin and can cause confusion, seizures, or coma.
Hypogonadism
Hypogonadism, or male testosterone deficiency, is failure of the testes to produce normal testosterone or sperm due to hypothalamic, pituitary, or testicular disease; diagnosed by symptoms plus repeated low morning testosterone, treated with testosterone replacement therapy.
Hypogravity
Hypogravity (reduced gravity, low gravity): gravity below Earth's 1 g, between 0 and 1 g. Covers lunar 0.16 g and Martian 0.38 g environments, studied via Apollo data, parabolic flight, drop towers, and simulators.
Hypohidrosis
Hypohidrosis, also called anhidrosis, is abnormally diminished or absent sweating, focal or generalized, caused by skin injury, rheumatic disease, drugs, neurologic disorders, or genetic conditions such as ectodermal dysplasia.
Hypohidrosis-electrolyte imbalance-lacrimal gland dysfunction-ichthyosis-xerostomia syndrome
HELIX syndrome (hypohidrosis-electrolyte imbalance-lacrimal gland dysfunction-ichthyosis-xerostomia syndrome) is a rare autosomal recessive CLDN10 claudinopathy causing salt-losing nephropathy with hypermagnesemia, hypokalemia, hypocalciuria, reduced sweating, tears, and saliva, ichthyosis, and enamel wear.
Hypohidrotic ectodermal dysplasia
Hypohidrotic ectodermal dysplasia (HED, Christ-Siemens-Touraine syndrome) is a hereditary disorder causing sparse hair, reduced sweating, and missing teeth, usually X-linked via EDA mutations; prenatal EDA1 protein replacement is under trial.
Hypohidrotic ectodermal dysplasia with immunodeficiency
Hypohidrotic ectodermal dysplasia with immunodeficiency (HED-ID, EDA-ID) is a rare primary immunodeficiency with sparse hair, hypodontia, and hypohidrosis, caused by IKBKG (NEMO) or NFKBIA mutations impairing NF-κB signaling.
Hypokalemia
Hypokalemia is a serum potassium below 3.5 mmol/L, caused by intracellular shift, renal or GI losses, or poor intake. Also called low potassium. Key features: ECG changes, arrhythmia risk with digoxin, magnesium-linked refractory cases, and IV repletion limits.
Hypokalemic periodic paralysis
Hypokalemic periodic paralysis, also called Westphall disease, is a rare inherited muscle ion channel disorder causing recurrent attacks of weakness with low blood potassium, usually beginning in childhood or adolescence.
Hypokaluria
Hypokaluria, also spelled hypokaliuria, is a decreased concentration of potassium in the urine, measured in 24-hour collections to tell renal potassium wasting apart from poor intake or gastrointestinal loss.
Hypolepis
Hypolepis, known as beadfern or bramble fern, is a genus of coarse terrestrial ferns in Dennstaedtiaceae, recognized by long-creeping rhizomes, prickly scrambling fronds, and round sori at the frond margin.
Hypolipoproteinaemia
Hypolipoproteinaemia (ICD-11 5C81), abnormally low plasma lipoproteins; primary forms include abetalipoproteinemia (MTTP), familial hypobetalipoproteinemia (APOB), chylomicron retention disease (SAR1B), PCSK9 and ANGPTL3 defects; also secondary causes.
Hypomagnesuria
Hypomagnesuria (ICD-11 MF98.5) is abnormally low urinary magnesium excretion, usually signaling magnesium depletion with intact renal conservation; normal excretion is 6-10 mEq/24 h, distinguishing it from renal magnesium wasting.
Hypomandibular faciocranial dysostosis
Hypomandibular faciocranial dysostosis (ORPHA1790, OMIM 241310) is an ultra-rare cranial malformation with severe mandibular and tongue hypoplasia, microstomia, laryngeal hypoplasia, and craniosynostosis; inheritance unknown, fewer than 1 in 1,000,000.
Hypomania
Hypomania: a mild manic-type mood episode (elevated, expansive, or irritable mood plus increased energy, at least 4 days, no marked impairment, hospitalization, or psychosis) defining bipolar II disorder; term coined by Erich Mendel in 1881.
Hypomenorrhea
Hypomenorrhea, or scanty/light menstrual periods, is decreased menstrual blood flow lasting two days or less for several months. Causes include stress, weight loss, hyperthyroidism, PMOS, perimenopause, and cervical stenosis; pooled prevalence in Iran was 5.25%.