Human health and medicine

Regadenoson anhydrous

Regadenoson anhydrous (Lexiscan, Rapiscan) is a selective A2A adenosine receptor agonist coronary vasodilator given as a fixed 0.4 mg IV bolus for myocardial perfusion imaging stress testing.

REGAIN (NCT02614261), Evaluation of Galcanezumab in the Prevention of Chronic Migraine: Eli Lilly phase 3 trial showing galcanezumab 120 mg and 240 mg reduced monthly migraine headache days more than placebo in chronic migraine.

Oct 20, 2026

Regdanvimab

Regdanvimab (CT-P59, Regkirona), Celltrion's monoclonal antibody for COVID-19; approved in South Korea 2021 and EU 12 Nov 2021, withdrawn in EU 14 April 2025; lost activity against Omicron.

Regenerative endodontic procedure

A regenerative endodontic procedure (REP) is a dental treatment using disinfection and induced bleeding to promote root development in an immature permanent tooth with a necrotic pulp.

Regenerative Endodontics

Regenerative endodontics (revascularization, revitalization) treats immature permanent teeth with necrotic pulps using disinfection, induced blood clots, and stem cell homing to promote root maturation, unlike apexification.

Regenerative peripheral nerve interface surgery

Regenerative peripheral nerve interface (RPNI) surgery implants a transected nerve into a free muscle graft, amplifying EMG signals for prosthetic control and reducing neuroma pain.

Regina S. Cunningham

Regina S. Cunningham is an American nurse scientist and executive who has led the Hospital of the University of Pennsylvania since 2017 and was elected to the National Academy of Medicine in 2022.

Regional chemotherapy

Regional chemotherapy is a cancer treatment that delivers anticancer drugs directly into the arteries supplying a tumor region, concentrating drug exposure while limiting toxicity to the rest of the body.

Regional Health Planning

Regional health planning: coordinated planning of health resources at a regional or multi-state level (MeSH D012040, 1977). Central to US health policy 1950s-1980s via Hill-Burton, CHP, NHPRDA, and CON review; ended in failure, survives in regional health authorities abroad.

Oct 20, 2026

Regional odontodysplasia

Regional odontodysplasia (ROD, ghost teeth) is a rare non-hereditary dental anomaly with hypoplastic, hypomineralized enamel and dentin in one quadrant, usually maxillary, showing ghost-like radiographs, delayed eruption, and extraction-based multidisciplinary treatment.

Registered nurse

Registered nurse (RN): a licensed nursing professional who provides and coordinates patient care. Requires an approved nursing program and state licensure; about 3.5 million U.S. jobs, median pay $97,550 (May 2025), 6% projected growth 2025-2035.

REGISTRY study

REGISTRY was a multi-national European observational study of Huntington's disease run by the European Huntington's Disease Network from 2004 to 2017, with annual assessments of thousands of participants.

Regulatory T cell

Regulatory T cell (Treg, FOXP3+CD4+CD25+): suppressive CD4+ T cell maintaining immune tolerance; discovered by Sakaguchi 1995, Foxp3 identified 2001; 2025 Nobel Prize; first approved Treg therapy Tregzi (2026).

Regurgitation (digestion)

Regurgitation (digestion): effortless return of gastric contents or recently ingested food to the mouth, a typical GERD symptom alongside heartburn, distinct from vomiting and from rumination syndrome, and mimicked by achalasia and gastroparesis.

Rehabilitation Centers

Rehabilitation centers (MeSH D012047) are health facilities providing programs for rehabilitating mentally or physically disabled people, offering medical, psychosocial, and vocational services in inpatient and outpatient hospital and community settings worldwide.

Rehabilitation of Speech and Language Disorders

Rehabilitation of speech and language disorders, also called speech and language therapy, helps people with speech or language disorders communicate; covers history, settings, evidence, and technology.

RehaMS trial

RehaMS (NCT04294979) is a completed single-group Italian trial at IRCCS San Raffaele Roma testing a 6-week intensive exercise program in MS (EDSS 4.5-6.5), measuring EDSS, MSFC, immune markers, vagal HRV, and TMS synaptic measures.

Reidar F. Sognnaes

Reidar F. Sognnaes (1911–1984) was a Norwegian-born dentist and oral biologist who served at Harvard before founding the UCLA School of Dentistry and publishing dental evidence identifying Adolf Hitler.

Reiki

Reiki, also known as Reiki healing, is a complementary health practice from Japan where practitioners place hands on or above the body to channel energy for healing, founded by Mikao Usui in 1922.

Reintubation

Reintubation is the reinsertion of a breathing tube into the trachea after extubation, needed when up to 15% of ICU patients fail to breathe on their own.

Reis-Bücklers corneal dystrophy

Reis-Bücklers corneal dystrophy (RBCD, granular corneal dystrophy type 3, CDB1) is a rare autosomal dominant TGFBI corneal dystrophy causing painful recurrent erosions and geographic Bowman layer opacities, distinguished from Thiel-Behnke dystrophy.

RELA fusion-positive ependymoma

RELA fusion-positive ependymoma, now ZFTA fusion-positive ependymoma (ST-EPN-ZFTA), a supratentorial grade II-III brain tumor of children and young adults driven by C11orf95/ZFTA-RELA fusion activating NF-κB.

Relaparotomy

Relaparotomy is a second full laparotomy through a previously operated abdomen, done to treat bleeding, leaking intestinal suture lines, bowel necrosis, or abdominal abscess.

Relapsed and refractory acute myeloid leukemia

Relapsed and refractory acute myeloid leukemia (R/R AML) is AML that fails induction chemotherapy or relapses after remission, treated with salvage regimens, mutation-directed drugs like gilteritinib, and allogeneic stem cell transplant.

Relapsing fever

Relapsing fever, a Borrelia spirochete infection with recurrent fever episodes; louse-borne (Borrelia recurrentis) and tick-borne (B. duttonii, B. hermsii, B. parkeri, B. miyamotoi) forms, driven by antigenic variation.

Relapsing polychondritis

Relapsing polychondritis (RP) is a rare autoimmune disease causing recurrent cartilage inflammation of ears, nose, and airway, with tracheomalacia, three clinical phenotypes, empirical steroid/biologic treatment, and VEXAS overlap.

Relapsing-remitting multiple sclerosis

Relapsing-remitting multiple sclerosis (RRMS), ICD-11 8A40.0, is the MS course of relapses with recovery and no progression between them; the initial course in about 85% of MS patients, treated with disease-modifying therapies.

Relative afferent pupillary defects

Relative afferent pupillary defects (RAPD), also called Marcus Gunn pupil, is an asymmetry in the afferent sensory limb of the pupillary light reflex caused by disease.

Relative polycythaemia

Relative polycythaemia (Gaisbock syndrome, spurious or apparent erythrocytosis, ICD-11 3A81.2) is a raised hematocrit with normal red cell mass caused by contracted plasma volume, from dehydration, diuretics, smoking, obesity, or hypertension; treated by hydration and risk-factor correction, not phlebotomy.