Laboratory Medicine Flashcards
Anatomic pathology includes
autopsy services, surgical pathology, cytology
Autopsy service
infrequent due to costs, imaging procedures, malpractice
Virtual autopsy
detailed body scan without dissection (becoming popular)
Surgical pathology
specimen collected from surgery must be examined (gross appearance, tissue processing (paraffin) and staining (H&E, special stain)
Cytology
pap smear, tissue brushings
Should cancer be diagnosed by cytology tissue brushing?
No, cannot see cell arrangement, use biopsy
Rembrandt, Dutch painter born in
1606
Liffey Swim
annual swim in dublin
Rembrandt had what famous painting in 1632
Abduction of Europa (oil-based)
Who performs a fine-needle aspiration?
pathologist
Pathologist do what procedures
fine-needle biopsy and surgical removal of tissue
Clinical pathology includes:
Hematology, transfusion, microbiology, chemistry, immunology, STAT lab, point-of-care testing
What type of specimen is used for ON-SITE diagnosis
frozen section
Panic value
sufficiently abnormal lab result value that indicates an immediate threat
Hematology - CBC
Measures Hgb, RBC count, and MCV; Calculates HCT, MCH, MCHC; WBC, platelets, % of WBCs, and RDW
Hematology - CBC with diff
CBC + count of normal/abnormal WBCs, morphology included
Hemoglobin is measured
measured from whole blood using CYANOMETHEMOGLOBIN formation
Counts of RBC, WBC, and platelets are obtained by
cell counter that measures conductance of cells passing through a small aperture (electrical impulse indicates cell type)
WBC population analysis
RBC lysis -> WBC automated flow cytometry (size, granules, shape, etc)
Automated flow cytometry
single cell characterization by size, shape, biochemical, or antigenic composition, by a scattering of light beam
Forward scatter in flow cytometry
diffraction = cell volume
Side scatter in flow cytometry =
refraction = measures internal cellular granularity
Pre-analytic phase
decision to perform test, specimen collection, etc
Analytic phase
Specimen analyzed
Post-analytic phase
report + interpretation and response to result
Peripheral blood smear procedure
blood smear, Wright stain, view whole slide (large cells at edge)
Blood clotting times - initial screening
PT and PTT
PT (prothrombin factor) measures
extrinsic pathway and common pathway factors (thromboplastin + Ca + plasma) [warfarin]
PTT (partial thromboplastin time)
evaluates intrinsic pathway and common pathway (partial thromboplastin + activator + Ca + plasma) [heparin]
Coagulation factor assay is based on
PT: thromboplastin for factors II, V, VII, and X
PTT: partial thromboplastin for factors VIII, IX, XI, and XII *ONLY patient’s plasma contains factors = clotting time
2 Sickle cell screening tests
sickling test and solubility test
Sickle cell test - sickling test
Blood + reducing agent (to reduce oxyhemoglobin to hemoglobin to accelerate sickling), examined for sickling cells presence
Sickle cell test - solubility test
lysed RBCs (saponin): deoxyhemoglobin S is insoluble in phosphate buffer; HbS = crystal formation; HbA is soluble
Hgb electrophoresis test
purified RBC hemolysate is separated by electrophoresis; PRINCIPLE for diagnosing hgb abnormalities
Blood banking procedure
Collect anti-coagulated whole blood -> spin to isolate RBCs and platelet-rich plasma -> spin to isolate platelets and plasma
Plasma contains
Igs, albumin, cryprecipitate (factor VIII, XIII, fibronectin, etc)
Cryopoor plasma
plasma without cryprecipitate (factor VIII, XIII, fibronectin, etc)
ABO/Rh forward typing tests
detects antigens on patient’s RBCs; mix RBC with anti-sera A/B/Rh; agglutination = blood type
ABO/Rh reverse typing tests
detects Abs in the patient’s plasma; mix patient’s plasma with reagent cells-A/B antigen; agglutination = presence of antibody
Apheresis
removal of blood, followed by separation of blood components (some components may be returned)
RBCs can be stored for
35-42d @ 4C
Platelet-rich fraction can be stored for
<5 days @ 25C
Therapeutic plasma exchange procedure
blood continuously withdrawn, separated into cellular and plasma, cellular component is mixed with FFP or colloid solution and returned to patient
Use for Therapeutic plasma exchange
Guillain Barre: to remove Ab’s against self
Gram Stain procedure
- Crystal violet (1m) 2. Iodine (1m) 3. Destain EtOH 4. Counterstain Safranin (1m); rxn, shape, arrangement
Plating
plate microbe in culture medium
Antimicrobial susceptibility test - disc diffuse method
discs embedded with different antimicrobial agents + suspension of organism; zones of inhibition are measured to determine susceptibility, intermediate, or resistant to antibiotic
Antimicrobial susceptibility test - dilution method
determines MIC (minimal inhibitory concentration); increasing dilutions of antimicrobial + agent; MIC = 1st tube which shows NO growth
Automated chemical profile includes
total protein, albumin, Ca2+, inorganic phosphate, cholesterol, glucose, creatinine, uric acid, Bilirubin, alkaline phosphatase, lactate dehydrogenase, aspartate aminotransferase (may include more)
Complete Chemical Profile
Albumin. Alkaline Phosphatase. Alanine Aminotransferase (ALT). Aspartate Aminotransferase (AST). Bilirubin (total and direct). Blood Glucose. Blood Urea Nitrogen. Calcium (Ca) in Blood. Carbon Dioxide (Bicarbonate). Chloride (Cl). Cholesterol and Triglycerides Tests. Creatinine and Creatinine Clearance. Gamma-Glutamyl Transferase (GGT). Lactate Dehydrogenase. Phosphate in Blood. Potassium (K) in Blood. Sodium (Na) in Blood. Total Serum Protein. Uric Acid in Blood.
(alanine aminotransferase) ALT/SGPT indicate pathology in
Liver, heart, skeletal muscle
Amylase indicates pathology in
pancreas, salivary gland
LDH indicates pathology in
most organs, esp heart, liver, lung, kidney
PSA indicate pathology in
prostate
LDH1:
heart, kidney, RBCs
LDH2/LDH3
lung, lymphocyte, platelets
LDH4
some types of leukemia
LDH5:
liver, skeletal muscle, neutrophils, prostate
What is all enzymes are high?
shock or infectious mononucleosis
International unit of enzyme
amount that catalyzes 1 umol of substrate/min under defined conditions
Alkaline phosphatase
bone, liver, all tissues
GGT/P
Liver, bile duct
AST (SGOT)
heart, liver, RBCs, skeletal muscle
isozyme
molecular variant of an enzyme or DIFFERENT enzyme that catalyzes the same reaction
LDH1 > LDH2 suspect
necrosis (infarction) of heart or kidney or hemolysis
High LDH5 suspect
liver and skeletal muscle damage
High LDH3 suspect
pulmonary infarct
Urinanalysis examines
appearance, specific gravity (density), pH, leukocytes, nitrites, protein, glucose, ketones, urobilinogen, bilirubin, and blood
Microscopic analysis of urine
examine sediment: cells, casts, crystals, microorganisms
Antinuclear antibody testing tests for
autoimmune disorders such as lupus erythematous, rheumatoid arthritis, and Sjogren Syndrome
Antinuclear antibody testing Procedure
patient’s serum + Hep2 cells; rinse; + anti-human IgG-fluorescent tag; Fluorescence microscopy detects presence/absence and pattern/titer of fluorescence
Immunoassay
any (colorimetric) assay that relies on antigen/antibody complex; used to detect and quantitate proteins, hormones, and amino acids
Non-competitive immunoassay (Type I)
Excess antibody + antigen; # of complexes DIRECTLY relates to [antigen]
Competitive immunoassay (Type II)
excess antibody + analyte + labeled-analyte; labeled and non-labeled compete; amt of signal from label-bound-antigen INVERSELY relates to [antigen]
Flow cytometry is used to diagnose
leukemia and lymphoma; precise identification of tumor cell types
Flow cytometry + mAB-tag
label cell surface antigens with mAb-tag; side scatter, forward scatter, and intensity determine cell type
Agglutination reactions procedure
large particle-antigen or particle-antibody; aggregates = presence of antigen or antibody in specimen
Agglutination reaction use
detect antibodies or antigens in specimen
Protein electrophoresis
detect presence and relative concentration of proteins (from serum, urine, or CSF)
Stat tests include tests
whose results are ESSENTIAL for patient care, lab runs test before continuing other work
Direct ELISA
Plate with specificity for antigen + patient unknown [antigen] + antibody-tag + substrate; colorimetric (primary Ab)
Indirect ELISA
Plate with antigen + patient unknown [antibody] + anti-human IgG-tag + substrate; colorimetric (Primary and Secondary Ab)
Sandwich ELISA
Plate with antibody + patient’s unknown [antigen] + primary Ab + secondary Ab + substrate
Electrolyte Panel includes
Na, K, Cl, CO2, glucose, BUN, creatinine
Stat tests usually involve
electrolytes, gases, chemistry profile, clotting/coagulation test, gram stain
Blood gases measure
pH, pCO2, pO2, O2 sat, total CO2
Blood gas requires
whole blood + 3 electrodes
Hydrogen electrode measures
pH
Carbon dioxide electrode works by
measuring pH change due to CO2 diffusion; [CO2] is directly related to pH change
ELISA spot used for
monitoring cellular immune responses by visualizing secretory products of individual activated cells
ELISA spot procedure
sandwich ELISA: immobilized specific antibody + secreting cells, remove cells and add primary antibody for secreted antigen + secondary-enzyme + substrate; visualize
Immunoflourescence immunoassay
cells from patient + antibody of interest + secondary-tag; visualize for presence/titer/pattern
oxygen probe for blood gas testing
complete electrochemical cell producing a current as oxygen migrates; current is DIRECTLY related to [O2]
Point-of-care testing
specimen testing outside of a lab/hospital, hand-held portable analyzers, miniaturized test
