25,729 articles
Levosalbutamol
Levosalbutamol (levalbuterol, Xopenex) is the active (R)-enantiomer of salbutamol, a short-acting beta2 agonist bronchodilator approved in 1999; meta-analyses show no consistent clinical superiority over racemic salbutamol in acute asthma.
Levosimendan
Levosimendan, sold as Simdax, is an inodilator drug developed by Finland's Orion Pharma for short-term intravenous treatment of severe heart failure, approved in Europe from 2000 but not by the FDA.
Levothyroxine
Levothyroxine (synthetic T4, L-thyroxine) is the first-line drug for hypothyroidism and a top-ten prescribed medicine worldwide; a narrow-therapeutic-index prodrug converted to T3, taken fasting, dosed ~1.6 mcg/kg/day by TSH.
Lewis R. Goldfrank
Lewis R. Goldfrank is an American emergency physician and medical toxicologist at NYU Langone Health and Bellevue Hospital, considered a founder of both emergency medicine and medical toxicology.
Lewis S. Edelheit
Lewis S. "Lonnie" Edelheit is an American physicist who helped develop CT X-ray imaging at General Electric, led its CT business, and headed corporate research until retiring in 2001.
Lewy body
Lewy body: intraneuronal aggregate of misfolded alpha-synuclein protein, discovered by Friedrich Lewy in 1912. Defines Parkinson's disease, dementia with Lewy bodies, and Parkinson disease dementia; definitive diagnosis requires autopsy.
Lewy body dementias
Lewy body dementias: dementia with Lewy bodies (DLB) and Parkinson disease dementia (PDD), alpha-synuclein deposit disorders causing hallucinations, parkinsonism, and fluctuating cognition; about 20% of dementias, no cure.
Leydig cell
Leydig cells, or interstitial cells of the testes, are steroid-producing cells in the testis that make testosterone and were named after Franz Leydig, who identified them in 1850.
Leydig cell hypoplasia
Leydig cell hypoplasia (Leydig cell agenesis, LCH, OMIM 238320) is a rare autosomal recessive 46,XY disorder of sex development caused by inactivating LHCGR mutations, causing low testosterone, female or ambiguous genitalia, and absent puberty in genetic males.
LFRR study
LFRR study: Lupus Family Registry and Repository, formerly LMRR, an OMRF family-based lupus genetics registry and biobank started 1995, holding 2,618 SLE cases from 1,954 pedigrees by 2010.
Lhermitte's sign
Lhermitte's sign, also called Lhermitte's phenomenon or the barber chair phenomenon, is an electric shock-like sensation down the spine triggered by neck flexion, best known as a symptom of multiple sclerosis.
Li Ching-Yuen (李清云)
Li Ching-Yuen (李清云), Chinese herbalist from Sichuan who died May 6, 1933; claimed age 197, reported as 256, but gerontologists classify the claim as a longevity myth with no verifiable evidence.
Li Wenliang (李文亮)
Li Wenliang (李文亮, 1986–2020) was a Wuhan Central Hospital ophthalmologist who warned classmates on WeChat on 30 December 2019 about SARS-like cases, was reprimanded by police for rumors, died of COVID-19 on 7 February 2020, and was posthumously declared a martyr.
Lianhua Qingke tablets
Lianhua Qingke tablets (连花清咳片), a 15-herb Chinese patent medicine by Yiling Pharmaceutical approved in China in May 2020 for acute tracheobronchitis cough with phlegm-heat obstructing lung syndrome; medical insurance Category B, OTC, Singapore-registered.
Lianpu Yin
连朴饮 (Lianpu Yin), a seven-herb Qing dynasty formula from Wang Mengying's Huolun Lun, clears damp-heat in the middle burner; originally for huoluo, now used for gastritis, ulcer, and reflux esophagitis.
Libby Zion Law
Libby Zion Law: New York State resident work-hour and supervision regulations (1987, Bell Commission) following the 1984 death of 18-year-old Libby Zion at New York Hospital; catalyst for ACGME national 80-hour duty-hour limits.
Libevitug (HH-003)
Libevitug (立贝韦塔单抗, HH-003, brand 华优诺) is Huahui Health's first-in-class human IgG1 antibody against HBV PreS1, blocking HBV/HDV entry via NTCP; NMPA conditionally approved it for chronic hepatitis D in January 2026.
Libido
Libido, or sexual desire, is the motivation for sexual activity; derived from Freud's drive construct. Governed by excitatory and inhibitory brain processes, hormones, and affected by stress, illness, and drugs; deficiency defines HSDD.
Libman–Sacks endocarditis
Libman–Sacks endocarditis, also called verrucous endocarditis, is a nonbacterial endocarditis with sterile vegetations on the heart valves, most often the mitral valve, in systemic lupus erythematosus and antiphospholipid syndrome, first described in 1924.
LIBREAST study
LIBREAST study (NCT04817813), European retrospective multicenter cohort of 100 women operated for breast cancer liver metastases 2010-2015; 5-year overall survival 60%, disease-free survival 29%, median survival 7 years after liver surgery.
LIBRETTO-001 trial
LIBRETTO-001 (NCT03157128) is the pivotal phase I/II single-arm trial of selpercatinib (LOXO-292, Retevmo) in RET-altered cancers; it supported FDA approval in RET fusion-positive NSCLC, with ORR 84% treatment-naive and 61% pretreated.
Libyan Centre for Dental Research
Libyan Centre for Dental Research (المركز الليبي لأبحاث طب الأسنان), a Libyan government dental research center established 2023 by ministerial decision 260, based in Zliten, under the Libyan Authority for Scientific Research, with eight specialty research departments.
Licarbazepine
Licarbazepine (10-hydroxycarbazepine, MHD) is the chiral active metabolite of the antiepileptics oxcarbazepine and eslicarbazepine acetate; S-enantiomer (eslicarbazepine) predominates, half-life about 8-10 hours, sodium-channel blocker.
Licensed practical nurse
Licensed practical nurse (LPN), called licensed vocational nurse (LVN) in California and Texas: a nurse licensed after a roughly one-year program and the NCLEX-PN, providing basic bedside care under RN supervision; median pay $64,400 (May 2025).
Licensed professional counselor
Licensed professional counselor (LPC), also LMHC or LCPC: a state-licensed master's-level mental health clinician who assesses, diagnoses, and treats behavioral disorders; credentialed via CACREP-accredited education, supervised fieldwork, and the NCE or NCMHCE exam, with cross-state practice through the Counseling Compact.
Lichen amyloidosis
Lichen amyloidosis, also called lichen amyloidosus, is a rare chronic primary localized cutaneous amyloidosis with intensely itchy hyperkeratotic papules on the shins, keratin-derived amyloid in the papillary dermis, OSMR/IL-31RA links, and refractory treatment.
Lichen planopilaris
Lichen planopilaris (LPP, follicular lichen planus) is a rare variant of lichen planus attacking hair follicles, causing scarring scalp alopecia in adults 40-60, mostly women; treated with corticosteroids.
Lichen planus
Lichen planus: chronic T-cell-mediated inflammatory disease of skin, oral and genital mucosa, scalp, and nails; Wickham striae, 1.14% oral malignant transformation rate, topical steroids first-line.
Lichen planus of the nails
Nail lichen planus (NLP) is a chronic inflammatory nail disorder affecting about 10% of lichen planus patients, causing ridging, thinning, pterygium, and possible permanent nail loss; treated mainly with intralesional corticosteroids.
Lichen planus pemphigoides
Lichen planus pemphigoides (lichen ruber pemphigoides) is a rare autoimmune subepidermal blistering disease combining lichen planus lesions with tense blisters and autoantibodies against type XVII collagen (BP180), distinguished from bullous lichen planus by positive immunofluorescence.