All articles starting with H
20,046 articles
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.
Hypoglycin A
Hypoglycin A is a heat-stable, toxic amino acid found in unripe ackee fruit and maple seeds, causing Jamaican vomiting sickness in people and atypical myopathy in horses.
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.
Hypolimnion
The hypolimnion is the cold, dense bottom layer of a stratified lake, lying beneath the thermocline and cut off from atmospheric oxygen during summer stratification.
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.
Hypomania Checklist
The Hypomania Checklist (HCL-32) is a 32-item self-report questionnaire screening for lifetime hypomanic symptoms, developed by Jules Angst and colleagues in 2005 to help identify bipolar-II disorder in depressed patients.
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%.
Hypomyces lactifluorum
Hypomyces lactifluorum, the lobster mushroom fungus, is a parasitic Hypocreaceae ascomycete that infects Russula and Lactarius hosts, especially Russula brevipes, turning them into orange, deformed, choice-edible lobster mushrooms sold across North America.
Hypomyelination of early myelinating structures
Hypomyelination of early myelinating structures (HEMS) is a rare X-linked genetic disorder in which early-myelinating brain regions stay poorly myelinated, presenting in infancy with nystagmus and ataxia.
Hypomyelination with atrophy of basal ganglia and cerebellum
H-ABC (hypomyelination with atrophy of basal ganglia and cerebellum) is a rare TUBB4A- or UFM1-related leukodystrophy with hypomyelination, putamen and cerebellar atrophy, dystonia, spasticity, and ataxia, onset in infancy.
Hypomyelination with brain stem and spinal cord involvement and leg spasticity
HBSL (hypomyelination with brain stem and spinal cord involvement and leg spasticity), also called aspartyl-tRNA synthetase deficiency, is an autosomal recessive DARS1 leukodystrophy causing leg spasticity, nystagmus, and hypomyelination on MRI.
Hyponatremia
Hyponatremia, a serum sodium below 135 mmol/L, is the most common electrolyte disorder, affecting 15–30% of hospitalized patients; classified by volume status and treated with hypertonic saline, fluid restriction, or vaptans.
Hypoparathyroidism
Hypoparathyroidism, low PTH with hypocalcemia, is a rare endocrine disorder, about 75% postsurgical, treated with calcium and vitamin D; palopegteriparatide (Yorvipath) is the first PTH replacement approved.
Hypoparathyroidism-sensorineural deafness-renal disease syndrome
Hypoparathyroidism-sensorineural deafness-renal disease syndrome, also called Barakat or HDR syndrome, is a rare autosomal dominant inherited disorder from GATA3 gene variants, first described in 1977.
Hypophosphatasia
Hypophosphatasia (HPP) is a rare inherited metabolic bone disease caused by ALPL gene variants that impair bone and tooth mineralization, causing rickets, osteomalacia, and premature tooth loss.
Hypophosphatemia
Hypophosphatemia: serum phosphate below 2.5 mg/dL (0.81 mmol/L). Also called low phosphate. Causes include refeeding, alcohol use disorder, DKA recovery, diuretics, hyperparathyroidism; severe cases cause weakness, rhabdomyolysis, seizures.
Hypophosphaturia
Hypophosphaturia (低リン酸尿症), ICD-11 MF98.6, is abnormally low urinary phosphate, a lab finding distinct from hypophosphatemia; it indicates nonrenal causes such as poor absorption or cellular shift rather than renal phosphate wasting.