115 articles
Laboratory medicine
Laboratory medicine (clinical pathology) is the medical discipline of analyzing blood, urine, and tissue specimens for diagnosis. Covers the total testing process, preanalytical error dominance, EQA, CLIA, and CAP/ISO 15189 accreditation.
Laboratory quality control
Laboratory quality control: IQC monitors precision within a lab via control charts (Levey-Jennings, Westgard rules), while EQA/proficiency testing independently compares accuracy between laboratories under ISO 15189.
Leukocyte Adherence Inhibition Test
Leukocyte Adherence Inhibition Test (LAI test), an in vitro assay of cell-mediated antitumor immunity first described by Halliday in 1972, in which cancer patients' leukocytes lose glass adherence when exposed to matching tumor extracts, mediated by LAIF and blocked by serum.
Leukocyte Count
Leukocyte count, also called WBC count or white blood cell count, is a CBC blood test measuring leukocytes, normally about 4,500–11,000 cells/µL in adults; high counts (leukocytosis) suggest infection or inflammation, low counts (leukopenia) suggest marrow or immune disease.
Leukocytosis
Elevated white blood cell count (leukocytosis): WBC above 11,000/mm³ in nonpregnant adults, usually reactive from infection, inflammation, stress, smoking, or drugs, but sometimes leukemia; classified by cell type.
Loss of heterozygosity analysis
Loss of heterozygosity (LOH) analysis is a genomics method detecting chromosomal regions where one allele is lost in tumors, used to locate inactivated tumor suppressor genes.
Lymphocyte Count
Lymphocyte count: the number of lymphocytes in blood, reported as a differential percentage (normally 20-40%) or absolute count (ALC). Low or falling ALC predicts mortality in critical illness and sepsis; ranges decline with age.
Microbiological analysis
Microbiological analysis detects, identifies, and quantifies microorganisms in food, water, environmental, and clinical samples using culture, microscopy, immunoassay, PCR, and metagenomic methods, governed by standards such as ISO/TC 34/SC 9 and CDC biosafety guidance.
Microbiological Techniques
Microbiological techniques: laboratory methods to detect, culture, identify, and study microorganisms, from microscopy, Gram stain, and pure-culture methods to 16S rRNA sequencing, metagenomics, PCR, and automated clinical diagnostics.
Micropore Filters
Micropore filters (microporous membrane filters) are 0.01-to-several-micrometer pore membranes of MCE, PVDF, PES, or PTFE that retain bacteria by sieve retention and adsorption; sterilizing grades retain 10^7 Pseudomonas diminuta per cm², though Acholeplasma and Leptospira can penetrate.
Microtomy
Microtomy is the laboratory technique of cutting tissue, usually embedded in paraffin wax, into thin slices with a microtome for examination under a light or electron microscope.
Microvascular Density
Microvascular density (MVD, microvessel density) is the measured density of microvessels in a tissue field, a surrogate biomarker of angiogenesis. Developed by Weidner et al. in 1991, it is assessed by endothelial immunohistochemistry (factor VIII, CD31, CD34, CD105) and studied as a prognostic marker in solid tumors.
Mitotic Index
The mitotic index (MI) is the ratio of cells undergoing mitosis to total cells in a population, reported as a percentage and used as a prognostic marker in tumor grading.
Molecular Typing
Molecular typing, or pathogen DNA fingerprinting, identifies microbial strains by genetic material to distinguish outbreak from nonoutbreak strains; methods span PFGE, MLST, cgMLST, and whole-genome sequencing.
Mycological Typing Techniques
Mycological typing techniques, or fungal typing, are laboratory procedures for identifying types and strains of fungi, spanning phenotypic biotyping, RFLP, karyotyping, MLST, microsatellite typing, and whole genome sequencing.
Neoplasm Grading
Neoplasm grading, also called histologic or tumor grade, describes how abnormal cancer cells look under a microscope and how quickly they are likely to grow and spread.
Neural autoantibody positive
Neural autoantibody positive (ICD-11 MA14.1A, 神経系自己抗体陽性) is a laboratory finding of antibodies against neuronal or glial antigens in serum or CSF, linked to autoimmune encephalitis and paraneoplastic syndromes but prone to false positives.
Neutralization assay
A neutralization assay, including virus and toxin neutralization variants, is a serological test measuring whether antibodies block viral infectivity or toxin activity, considered the reference method for protective antibodies.
Neutralization Tests
Neutralization tests are serology assays measuring functional antibodies that block virus infection of cell cultures. Formats include PRNT, microneutralization, pseudovirus tests, and surrogate RBD-ACE2 blocking ELISAs; PRNT is the gold standard.
Open flow microperfusion
Open flow microperfusion (OFM) is a minimally invasive method that continuously collects unfiltered interstitial fluid from tissue through a membrane-free catheter, measuring drugs, metabolites, and proteins over time.
Osmotic Fragility
Osmotic fragility (erythrocyte osmotic fragility test, OFT, NESTROFT, AGLT) measures red blood cell resistance to lysis in hypotonic saline; spherocytes in hereditary spherocytosis lyse at higher NaCl, thalassemia cells resist, and the test lacks specificity for autoimmune hemolytic anemia.
Paraffin embedding
Paraffin embedding is a histology technique in which fixed tissue is infiltrated with molten paraffin wax, forming FFPE blocks cut into thin sections for microscopy.
Parasite Egg Count
A parasite egg count is a laboratory measurement of parasite eggs per gram of feces, estimating helminth infection intensity in humans and animals and guiding public-health deworming programs.
Pathologic Complete Response
Pathologic complete response (pCR), or pathologic complete remission: no residual cancer found microscopically in surgical specimens after neoadjuvant therapy. Prognostic in breast, digestive, lung cancers; FDA accelerated-approval endpoint in breast cancer; weak trial-level surrogate.
Photomicrography
Photomicrography: photographing magnified images through a microscope; distinct from microphotography. Pioneered by Talbot (1830s) and Woodward (1870s sunlight apparatus); now digital, with QC metrics, OME metadata standards, and contests like Nikon Small World.
Plastination
Plastination, invented by Gunther von Hagens in 1977 at Heidelberg, preserves anatomical specimens by replacing water and fat with curable polymers via vacuum impregnation, yielding dry, odorless, durable teaching and exhibition specimens (Body Worlds).
Positive sputum culture
Positive sputum culture: growth of pathogenic bacteria or fungi from coughed-up lung mucus (phlegm), used to diagnose pneumonia, tuberculosis, and bronchiectasis; interpretation limited by oropharyngeal contamination and prior antibiotics.
Positive throat culture
A positive throat culture is a laboratory result showing group A Streptococcus growing from a throat swab, confirming strep throat and usually leading to antibiotics.
Pre-Analytical Phase
Pre-analytical phase (pre-examination phase): all laboratory testing steps from test ordering through patient preparation, sample collection, transport, and preparation before analysis; source of 60-70% of laboratory errors, led by hemolysis.
Primary Cell Culture
Primary cell culture: freshly isolated, non-immortalized cells grown in vitro, retaining native tissue morphology and function; finite lifespan (Hayflick limit, ~6-10 passages), unlike immortalized cell lines.