Hematology: Laboratory Evaluation of Secondary Hemostasis

Questions and Answers

What is the purpose of evaluating clotting factors in Secondary Hemostasis?

Identify factor deficiencies

Which tube is checked first for clotting formation in the process described?

Tube #1

What method is used to check clotting time in tube #3?

Slide/Drop Method

Why is the Activated Clotting Time considered insensitive to factor deficiencies?

It provides no information on specific clotting factors Signup and view all the answers

What issue makes the Capillary Tube Method unreliable for producing results?

Too many errors in the timing process Signup and view all the answers

Which method can specify factor deficiency but is insensitive to identifying the exact deficient clotting factor?

Dale and Laidlaw's Method Signup and view all the answers

What is the purpose of using a capillary tube with a blue mark (without anticoagulant) in a blood clotting test?

To accelerate the clotting process Signup and view all the answers

Which clotting factor deficiency cannot be specifically identified using the test described in the text?

Factor VIII deficiency Signup and view all the answers

What is the primary reason for the obsolescence of the Lee and White whole blood coagulation time method?

It is too sensitive to factor deficiencies Signup and view all the answers

Which factor is NOT part of the common pathway in the laboratory evaluation of intrinsic and common pathways as stated in the text?

Factor XIII Signup and view all the answers

What is the activator used in the activated clotting time test described in the text?

Diatomaceous earth Signup and view all the answers

Why are problems related to intrinsic and common pathways often associated with liver diseases according to the text?

As the liver produces most of the necessary clotting factors Signup and view all the answers

Study Notes

Laboratory Evaluation of Secondary Hemostasis

To evaluate clotting factors (coagulation factors) for Secondary Hemostasis, collect 4 mL of blood and divide it into three tubes.
Start timing as 1 mL of blood is transferred into tube #3, then 1 mL for tube #2 and tube #1, and incubate.

Clotting Time Methods

Slide/Drop Method: Useful for children, uses a small amount of blood, and is done by capillary puncture.
Capillary Tube Method/Dale and Laidlaw's Method: Uses a capillary tube with a blue mark, no anticoagulant; not usually performed due to skin puncture risk.
Lee and White Whole Blood Coagulation Time: An obsolete method, insensitive to factor deficiencies.

Activated Clotting Time (ACT)

Used for patients undergoing heparin therapy.
An activator, diatomaceous earth (12mg diatomide), is used to stimulate clotting factors.
Samples are incubated at 37℃; normal range: 75-120 secs, and 140-185 secs for patients undergoing heparin therapy.

Laboratory Evaluation of Intrinsic and Common Pathways

Intrinsic Pathway: Factors XII, XI, IX, VIII, HMWK, PK.
Common Pathway: Factors X, V, II, I, XIII (XIII not part of the common pathway).
Problems with intrinsic and common pathways are related to liver diseases since the liver produces clotting factors.
Affected by circulating anticoagulants (e.g., heparin, which prolongs clotting time) and hypofibrinogenemia (low fibrinogen levels).