Blood is the most important tissue in the body as it transports oxygen, protein, blood cells, and drugs.
Blood metabolizes through ion exchanges.
Blood is involved in immunity through white blood cells (WBC).
Blood is involved in hemostasis through platelets and coagulation factors.
The 3.2% Sodium Citrate Tube is a light tube with an A:B ratio of 1:9.
The 3.2% Sodium Citrate Tube must not be hemolyzed or lipemic.
The sample should be stored at room temperature (22 - 25°C).
A short draw in the 3.2% Sodium Citrate Tube results in a whole blood volume that is less than 90% of the required volume or less than the manufacturer-specified minimum.
If a clot is present in the specimen, it must be removed prior to centrifugation.
Visible hemolysis in the 3.2% Sodium Citrate Tube indicates vitro activation of platelets and coagulation and results will be unreliable.
Lipemia or icterus in the 3.2% Sodium Citrate Tube may cause optical instruments to not measure clots in cloudy or highly colored specimens.
Advanced partial thromboplastin time (aPTT) detects disorders involving the intrinsic and common pathway.
Capillary tube/Dale and Laidlaw: break capillary tube every 30 seconds and check for fibrin clot (use plain or blue banded capillary tube).
Venous blood (start timing after collection) is placed in tubes 3, 2, 1 and put in a water bath at 37°C.
Whole Blood/Lee and White (N.V.: 7 - 15mins) uses a glass tube: 13 x 100mm.
The results of the 3 test tubes are averaged.
Modern coagulation tests screen for defects in the coagulation pathway.
The extrinsic pathway is activated by tissue damage resulting from trauma.
The intrinsic pathway is activated by damage in the vascular wall.
There are two main types of coagulation screening tests: Prothrombin time (PT) and Advanced partial thromboplastin time (aPTT).
Prothrombin time (PT) detects disorders involving the extrinsic and common pathway.
Prolonged Prothrombin time (PT) indicates factors VII, V, X, II, I deficiencies.
Normal Prothrombin time (PT) indicates factors VIII, IX and XIII deficiencies.
The tubes are tilted every 30 seconds until they can be inverted without flowing out and the timer is stopped.
The Antithrombin Ill assay principle is the neutralization of serine proteases, with the first step being to neutralize thrombin with test plasma.
The Activated clotting time is a bedside test to monitor heparin therapy.
Abnormal PT combined with abnormal PTT is associated with factors I, very rare.
In the Thrombin time procedure, platelet-poor plasma is diluted 1:10 with Owren's buffer, aqueous solution of 28.4 mM barbital, 125.4 mM sodium chloride, and 0.05 % sodium azide.
Abnormal PT indicates a factor V II defect ONLY.
Abnormal PTT indicates factors XI, IX, VIII, and is not associated with bleeding.
Abnormal PT combined with abnormal PTT and abnormal APTT is associated with anticoagulants, DIC, liver disease, and vitamin K deficiency.
Fibrinogen Assay is a procedure modified by Clauss that minimizes the effect of heparin.
The 5M Urea Solubility Test is used to detect factor X II I deficiency, as factor XIII stabilizes fibrin clot.
The Bethesda titer for anti-factor VIII inhibitor is performed by incubating platelet-poor plasma with an equal volume of pooled normal plasma at 37°C for 2 hours, then performing APTT on the mixture.
Combined abnormal PT and PTT indicates factors X, V, II, and is very rare.
In the Fibrin split product test, the clotting process is monitored during streptokinase therapy.
Reptilase Time uses Bothrops atrox venom, a thrombin like enzyme, and is unaffected by heparin therapy.
The International sensitivity index (ISI) is a value given to a batch of PT reagents when compared to a reference tissue factor, usually 1,0 to 3.0, with 1,3 to 1.5 being the ideal range.
Thrombin Time uses commercially prepared thrombin from bovine sources and triggers the formation of a fibrin clot.
Activated Partial Thromboplastin Time (APTT) uses a reagent that includes phospholipids and a negatively charged particulate activator (silica, kaolin, celite, ellagic acid).