Medical terms, defined.

Ixekizumab (Taltz) is a humanized IgG4 monoclonal antibody that binds and neutralizes IL-17A. It is used for moderate-to-severe plaque psoriasis, psoriatic arthritis, ankylosing spondylitis, non-radiographic axial spondyloarthritis, and...

Secukinumab (Cosentyx) is a fully human IgG1κ monoclonal antibody that neutralizes interleukin-17A (IL-17A). It is used for moderate-to-severe plaque psoriasis, psoriatic arthritis, ankylosing spondylitis/non-radiographic axial spondyloa...

Pertuzumab (Perjeta) is a humanized monoclonal antibody that binds the extracellular dimerization domain (subdomain II) of HER2, blocking HER2 heterodimerization (especially with HER3). It is used with trastuzumab and chemotherapy in HER...

Ustekinumab (Stelara) is a human monoclonal IgG1 antibody that binds the shared p40 subunit of IL-12 and IL-23, blocking Th1 and Th17 differentiation and signaling. It is used for moderate-to-severe plaque psoriasis, psoriatic arthritis,...

Dupilumab is a fully human monoclonal IgG4 antibody that binds the IL-4 receptor alpha subunit, blocking both IL-4 and IL-13 signaling (Th2 pathway). It is used for atopic dermatitis, asthma (eosinophilic or oral steroid-dependent), chro...

Obinutuzumab is a humanized, glycoengineered, type II anti-CD20 monoclonal antibody used in CLL (with chlorambucil, or venetoclax), follicular lymphoma, and (more recently) lupus nephritis. Compared with rituximab (type I), it produces g...

Brentuximab vedotin (Adcetris) is an antibody-drug conjugate targeting CD30, used for CD30+ lymphomas such as Hodgkin lymphoma and anaplastic large cell lymphoma. It delivers the antimitotic agent MMAE into cells. Key toxicities: periphe...

Vedolizumab (Entyvio) is a humanized monoclonal IgG1 antibody against α4β7 integrin on gut-homing T lymphocytes. It blocks binding to MAdCAM-1 on gut endothelium, giving gut-selective anti-inflammatory effects. It is used for moderate-to...

Daratumumab is a human IgG1-kappa monoclonal antibody against CD38, which is highly expressed on multiple myeloma plasma cells. It is a cornerstone of treatment for multiple myeloma, both newly diagnosed and relapsed/refractory, and is u...

Basiliximab is a chimeric (murine/human) monoclonal antibody against the alpha chain of the IL-2 receptor (CD25) on activated T cells. It is used for induction immunosuppression to prevent acute rejection in kidney transplantation, and i...

Abaloparatide is a synthetic PTHrP (parathyroid hormone-related peptide) analog (PTHrP 1-34) given as a daily subcutaneous injection. It is an anabolic osteoporosis drug that stimulates osteoblasts through the PTH1 receptor, increasing b...

Aflibercept (Eylea, Zaltrap) is a recombinant fusion protein ("VEGF trap") made of VEGFR-1 and VEGFR-2 extracellular domains fused to the Fc portion of human IgG1. It binds VEGF-A, VEGF-B, and placental growth factor (PlGF). It is given...

Ravulizumab (Ultomiris) is a long-acting humanized monoclonal antibody against complement protein C5 that blocks cleavage of C5 into C5a and C5b, preventing formation of the membrane attack complex (MAC). It is used for paroxysmal noctur...

Alemtuzumab is a humanized monoclonal IgG1 antibody against CD52 (on B and T cells, monocytes, NK cells, macrophages) that causes complement- and antibody-dependent cell lysis. It is used for B-cell chronic lymphocytic leukemia (Campath)...

Ranibizumab (Lucentis) is a recombinant humanized monoclonal antibody Fab fragment that binds and inhibits all isoforms of VEGF-A. It is given by intravitreal injection to treat neovascular (wet) age-related macular degeneration, diabeti...

Dronedarone (Multaq) is a non-iodinated benzofuran amiodarone derivative, a multichannel-blocking (class III, with class I, II, IV properties) antiarrhythmic used to reduce hospitalization for AF in patients with paroxysmal/persistent AF...

Isosorbide mononitrate is a long-acting oral organic nitrate used for chronic stable angina prophylaxis. It is a prodrug-independent NO donor that causes venodilation (↓preload) and, at higher doses, arteriolar dilation, reducing myocard...

Sodium nitroprusside is a rapid-acting, short-acting (half-life ~2 min) IV vasodilator that releases nitric oxide (NO), dilating both arteries and veins (balanced). It is used for hypertensive emergencies and acute decompensated heart fa...

Isosorbide dinitrate is an oral organic nitrate vasodilator used for angina prophylaxis and, combined with hydralazine, for HFrEF (especially in self-identified Black patients, per A-HeFT). It is a NO donor that increases cGMP in vascula...

Lipoprotein(a) is an LDL-like particle in which apolipoprotein(a) is covalently linked (disulfide bond) to apoB-100. Its plasma level is ~70-90% genetically determined (LPA gene), largely unaffected by diet or exercise. It is an independ...

Lipoprotein(a) [Lp(a)] is an LDL-like particle in which apolipoprotein(a) is covalently linked via a disulfide bond to apoB-100. Its plasma level is ~90% genetically determined (LPA gene) and is an independent, causal risk factor for ASC...

Apolipoprotein A-I (ApoA-I) is the major structural protein of HDL (~70% of HDL protein), synthesized by the liver and intestine. It activates LCAT and mediates reverse cholesterol transport via ABCA1 interaction, making it atheroprotect...

Apolipoprotein E (ApoE) is a ligand on chylomicron remnants, IDL, VLDL, and HDL that mediates hepatic uptake via LDL receptor and LRP-1. The ε4 allele is the major genetic risk factor for late-onset Alzheimer disease, while ε2 homozygosi...

Intermediate-density lipoprotein (IDL) is a transient remnant formed when lipoprotein lipase hydrolyzes triglycerides from VLDL. It is either taken up by the liver (via LDL receptor/LRP recognizing apoE) or further processed by hepatic l...

LDL (low-density lipoprotein) cholesterol is the main cholesterol-carrying lipoprotein delivering cholesterol from the liver to peripheral tissues. It is the primary atherogenic lipoprotein and the major target of lipid-lowering therapy...

HDL (high-density lipoprotein) cholesterol mediates reverse cholesterol transport, carrying cholesterol from peripheral tissues and vessel walls back to the liver. Higher levels are epidemiologically associated with lower ASCVD risk, but...

LDL is the major cholesterol-carrying lipoprotein in blood, formed from VLDL/IDL metabolism by lipoprotein lipase and hepatic lipase. Its core apolipoprotein is ApoB-100, and it delivers cholesterol to peripheral tissues and the liver vi...

VLDL is a triglyceride-rich lipoprotein assembled in the liver (apoB-100, C-II, E) that carries endogenous triglycerides to peripheral tissues. Lipoprotein lipase (LPL) removes its triglycerides, converting VLDL → IDL → LDL. Elevated VLD...

HDL is the smallest, densest lipoprotein (highest protein:lipid ratio) and mediates reverse cholesterol transport, carrying cholesterol from peripheral tissues and vessel walls back to the liver. Higher levels are epidemiologically assoc...

Chylomicron remnants are the triglyceride-depleted, cholesterol ester-rich particles left after lipoprotein lipase (LPL) hydrolyzes chylomicron triglycerides in capillaries. They retain apoB-48 and acquire apoE from HDL, allowing hepatic...

Lecithin-cholesterol acyltransferase (LCAT) is a plasma enzyme, activated by apoA-I on HDL, that esterifies free cholesterol by transferring a fatty acid from lecithin (phosphatidylcholine) to cholesterol, forming cholesteryl esters. Thi...

CETP (cholesteryl ester transfer protein) is a plasma protein that transfers cholesteryl esters from HDL to VLDL/IDL/LDL (apoB-containing lipoproteins) in exchange for triglycerides. This lowers HDL-C and raises LDL/VLDL remnants, so CET...

Tension-type headache (TTH) is the most common primary headache disorder, characterized by bilateral, non-pulsatile, pressing/band-like pain of mild-to-moderate intensity that is NOT worsened by routine physical activity and lacks nausea...

Epididymitis is inflammation of the epididymis, presenting as acute unilateral scrotal pain and swelling, often with dysuria or urethral discharge. In men <35 it is usually caused by Chlamydia trachomatis and Neisseria gonorrhoeae; in me...

Pelvic inflammatory disease (PID) is an ascending polymicrobial infection of the upper female genital tract (endometritis, salpingitis, tubo-ovarian abscess, pelvic peritonitis), most often caused by Chlamydia trachomatis and Neisseria g...

A tubo-ovarian abscess (TOA) is an inflammatory, encapsulated collection of pus involving the fallopian tube and ovary, most often a complication of ascending pelvic inflammatory disease (PID) from Chlamydia trachomatis, Neisseria gonorr...

Glioblastoma (GBM, WHO grade 4 astrocytic tumor, IDH-wildtype) is the most common and most malignant primary adult brain tumor. It classically appears as a ring-enhancing, "butterfly" lesion crossing the corpus callosum with central necr...

Cluster headache is a trigeminal autonomic cephalalgia: severe, strictly unilateral periorbital/orbital pain lasting 15–180 minutes, occurring in clusters (up to 8/day) with ipsilateral autonomic signs (lacrimation, rhinorrhea, ptosis, m...

Astrocytoma is a primary CNS glial tumor arising from astrocytes, graded by WHO from low-grade (pilocytic, grade 1) to the highly malignant glioblastoma (IDH-wildtype, grade 4). Pilocytic astrocytoma is the classic pediatric cerebellar t...

Squamous cell carcinoma (SCC) of the lung is a non-small cell lung cancer strongly associated with smoking. It typically arises centrally in a main or lobar bronchus, often cavitates, and is classically linked to PTHrP-mediated hypercalc...

Oligodendroglioma is a slow-growing diffuse glioma of oligodendrocyte lineage, classically in the frontal lobe of adults. It is defined by IDH1/2 mutation plus 1p/19q co-deletion. Histology shows "fried egg" cells with perinuclear halos...

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematopoietic stem cell disorder caused by somatic PIGA mutation (X-linked), leading to deficient GPI-anchored proteins (CD55/DAF and CD59/MIRL) on blood cells. This causes...

A solitary pulmonary nodule (SPN) is a single, round or oval lung opacity ≤3 cm in diameter, surrounded by aerated lung parenchyma, without associated atelectasis, hilar enlargement, or pleural effusion. Most are benign (granulomas, hama...

Heparin-Induced Thrombocytopenia (HIT) is an immune-mediated adverse reaction to heparin in which IgG antibodies against platelet factor 4 (PF4)–heparin complexes activate platelets. It causes thrombocytopenia (typically 5–10 days after...

Immune thrombocytopenia (ITP; formerly "idiopathic thrombocytopenic purpura") is an autoimmune disorder in which IgG autoantibodies against platelet glycoproteins (GP IIb/IIIa, Ib/IX) cause splenic macrophage destruction of platelets and...

Disseminated Intravascular Coagulation (DIC) is an acquired, life-threatening syndrome of widespread pathologic activation of coagulation, causing microvascular thrombi, consumption of platelets and clotting factors, and secondary fibrin...

Histaminase (diamine oxidase) is an enzyme that degrades histamine by oxidative deamination, helping terminate histamine's biological activity. It is notably produced in increased amounts by the placenta during pregnancy, which can reduc...

Filgrastim is a recombinant human granulocyte colony-stimulating factor (G-CSF) used to stimulate neutrophil production in bone marrow. It is primarily used to treat or prevent chemotherapy-induced neutropenia and to mobilize hematopoiet...

Major basic protein (MBP) is a cytotoxic protein stored in the granules of eosinophils that plays a key role in the body's defense against helminthic (parasitic worm) infections. It causes direct damage to parasite membranes and also con...

Arylsulfatase B (ARSB, N-acetylgalactosamine-4-sulfatase) is a lysosomal enzyme required for the stepwise degradation of glycosaminoglycans (GAGs), specifically dermatan sulfate and chondroitin-4-sulfate. Deficiency causes Mucopolysaccha...