115 articles
Double diffusion (immunology)
Double diffusion, or the Ouchterlony double immunodiffusion assay, is an immunological technique in which antigen and antibody diffuse toward each other through agar gel, forming precipitin lines.
Electrochemiluminescence assay
An electrochemiluminescence (ECL) assay is a bioanalytical method that quantifies biomolecules by generating light through electrochemical reactions at an electrode, most commonly in sandwich immunoassays using a ruthenium label.
Elevated C-reactive protein
Elevated C-reactive protein (raised CRP, hs-CRP elevation; ICD-11 MA14.15) is a nonspecific blood marker of inflammation from infection, trauma, or chronic disease; normal below 0.3 mg/dL, marked above 10 mg/dL.
Elevated erythrocyte sedimentation rate
Elevated erythrocyte sedimentation rate (ESR, sed rate, Westergren sedimentation rate): red cells settle faster than normal in one hour, a nonspecific marker of inflammation; ICD-11 MA1A.0.
Erythrocyte Count
Erythrocyte count (RBC count, red count): a blood test measuring red blood cells per volume, almost always part of a CBC. Normal about 4–6 × 10^12/L, lower in women; used to diagnose anemia and polycythemia.
Erythrocyte Indices
Erythrocyte indices (RBC indices): MCV, MCH, MCHC, and RDW, calculated from the complete blood count to classify anemia by red cell size and hemoglobin content; Wintrobe-derived, with discrimination formulas of limited cross-population reliability.
External quality assessment
External quality assessment, also known as proficiency testing, is a laboratory medicine procedure in which an external organization sends blinded specimens to laboratories and evaluates their results.
Fibrinogen i 125
Fibrinogen i 125 (^{125}I-fibrinogen) is iodine-125-labeled fibrinogen used from 1965 in the fibrinogen uptake test to detect deep vein thrombosis; accurate for calf clots but limited in the thigh and later superseded.
FIGLU Test
FIGLU test, or formiminoglutamic acid test, a urine test measuring formiminoglutamic acid after an oral histidine load; elevated levels indicate folate or vitamin B12 deficiency or liver disease.
Finding of alcohol in blood
Finding of alcohol in blood (ICD-11 MA13.1) is laboratory ethanol measurement: enzymatic ADH assay on serum/plasma in hospitals, headspace gas chromatography on whole blood in forensic labs, with stricter uncertainty rules for legal use.
Finding of cocaine in blood
Finding of cocaine in blood: laboratory detection of cocaine, benzoylecgonine, and ecgonine methyl ester in blood. Covers detection windows, GC-MS/LC-MS confirmation, sodium fluoride preservation, and why concentrations predict neither toxicity nor postmortem levels.
Flocculation Tests
Flocculation tests are serological precipitin assays in which antigen-antibody complexes form visible clumps over a narrow antigen-antibody ratio. Key examples: VDRL and RPR syphilis tests and the Ramon Lf test for toxoid vaccines.
Focus reduction neutralization assay
The focus reduction neutralization assay (FRNT), or focus reduction neutralization test, is a serological assay measuring neutralizing antibodies against viruses such as dengue and SARS-CoV-2.
Formalin fixation
Formalin fixation preserves tissue by immersing it in dilute formaldehyde, which cross-links proteins and nucleic acids so microscopic structure, antigens, and biomolecules survive storage, staining, and molecular testing.
Frozen Sections
Frozen sections: rapid intraoperative histopathology of fresh frozen tissue cut on a cryostat, also called frozen section biopsy or intraoperative consultation; accuracy 92-98% versus permanent sections, used for margins, diagnosis, and lymph nodes.
Genotoxicity
Genotoxicity: damage to genetic material by chemical, physical, or biological agents. Assessed via the Ames test, micronucleus, chromosomal aberration, comet, and transgenic rodent OECD test guidelines.
Hemadsorption Inhibition Tests
Hemadsorption inhibition tests are virological assays in which erythrocytes bind virus-infected cell monolayers and specific antiserum blocks that binding, identifying hemadsorbing viruses such as influenza, parainfluenza, and mumps, or quantifying myxovirus antibodies.
Hemagglutination assay
The hemagglutination assay is a laboratory test that detects viruses such as influenza by watching red blood cells clump; its inhibition form measures antibodies instead.
Hemoglobinometry
Hemoglobinometry (haemoglobinometry): measurement of blood hemoglobin concentration to screen and diagnose anemia. Cyanmethemoglobin method and automated analyzers are reference standards; HemoCue dominates point-of-care field testing; WHO 2024 guidance favors venous blood.
Hemolytic Plaque Technique
Hemolytic plaque technique (Jerne plaque assay, plaque-forming cell assay): 1963 Jerne and Nordin method counting single antibody-secreting cells by complement lysis of sheep red blood cells in agar; predecessor of ELISPOT.
Histocytochemistry
Histocytochemistry (cytochemistry) is the study of intracellular distribution of chemicals, reaction sites, and enzymes via staining, isotope uptake, and electron microscopy; immunohistochemistry, PAS, and Prussian blue are its MeSH subfields.
Histocytological Preparation Techniques
Histocytological preparation techniques (MeSH D016591) are methods for preparing cells and tissues for microscopy: fixation, paraffin embedding, microtomy, staining, and cell blocks, from specimen handling to FFPE and frozen sections.
Histological Techniques
Histological techniques: methods of preparing tissue (fixation, embedding, sectioning, staining) for microscopic study of structure and pathology; MeSH D006652; H&E standard, IHC from the 1980s.
Immunoelectrophoresis
Immunoelectrophoresis (IEP) is a laboratory method, introduced by Grabar and Williams in 1953, that separates proteins by electrophoresis and identifies them with antibodies as stained precipitin arcs.
Immunologic Cytotoxicity Tests
Immunologic cytotoxicity tests are laboratory assays showing how lymphocytes, antibodies, or complement damage target cells, covering cell-mediated killing assays and antibody-mediated crossmatches used to prevent transplant rejection.
Immunologic Monitoring
Immunologic monitoring (immune monitoring, MeSH D015166): testing of immune status in diagnosis and therapy of cancer, immunodeficiency, autoimmune disease, and transplantation, using humoral assays, flow and mass cytometry, and functional T-cell assays.
ISO 15189
ISO 15189 is an international standard specifying quality and competence requirements for medical laboratories, covering personnel, equipment, testing, and result reporting; the current edition was published in 2022.
Killer cell immunoglobulin-like receptor typing
Killer cell immunoglobulin-like receptor typing, or KIR typing, is a genotyping method that determines which KIR genes a person carries, in what copy number, and at which alleles.
Kveim Test
Kveim test, or Kveim-Siltzbach test, an intradermal skin test for sarcoidosis using heat-treated sarcoid tissue suspension; a granulomatous nodule at the injection site, read histologically after 4 to 6 weeks, indicates active sarcoidosis.
Laboratory Critical Values
Laboratory critical values, also called panic or alert values, are life-threatening test results labs must report immediately. Introduced by Lundberg in 1972; required by CLIA, Joint Commission, and ISO 15189.