Coagulation

Important findings :

1. Bleeding time-Normal
2. Clotting time- prolonged
3. APTT- prolonged
4. Prothrombin time- Normal
5. Platelet count- Normal

1^st four clotting factor are essential

Erythroblastosis fetalis-Hemolytic disease of newborn

Rickets, Fragile-X syndrome—X-linked dominant

[Ganong 24th p-565]

1^st four are essential

Explanations: 1st four clotting factors are regarded as primary clotting factors.

[Ganong 24th p-569]

Vit-k dependent blood clotting factors
 1. Factor ll(prothrombin)
2. Factor Vll
3. Factor IX  
4. Factor X

Explanations:
Serum contains no fibrinogen

Explanations:
The normal range for INR in a healthy person is 0.9 to 1.3. A high INR level (e.g., 4 or 5) indicates a high risk of bleeding, whereas a low INR (e.g., 0.5) suggests that there is a chance of having a clot. Patients undergoing warfarin therapy usually have an INR of 2.0 to 3.0.

Explanations:
Activation of Factor X is pivotal in both pathways.

If whole blood is allowed to clot and the clot is removed the remaining fluid is called serum.

Ref: Guyton 14th; P-482

• Heparin is a highly sulfated glycosaminoglycan with the highest negative charge density of any known biological molecule. It is a naturally occurring anticoagulant produced by mast cells and basophils that plays an important role in vivo in the fine balance of anticoagulant and procoagulant processes. Although it does not break down preformed clots like tissue plasminogen activator, it instead potentiates the progression of the body’s natural clot lysis mechanisms to prevent the formation of clots.

• Heparin is administered parenterally because it is not absorbed in the gut due to its high negative charge and size; intramuscular injections are avoided because of the risk of developing hematomas. Subcutaneous administration is predominantly given for deep vein thrombosis prophylaxis. In order to maintain its antithrombotic effect throughout the duration of percutaneous coronary intervention (PCI), heparin must be rebolused or continually infused because of its short half-life.

• Heparin is the most commonly used anticoagulant in the world administered to minimize thrombotic complications during PCI; its onset of action is immediate after intravenous administration. In addition to avoiding thrombotic complications, anticoagulation strategies must be designed to avoid major bleeding complications, as they are associated with increased morbidity, mortality, and cost.

• The combination of heparin and glycoprotein (GP) IIb/IIIa inhibitors has a potent anti-ischemic effect, but also has an increased risk of serious bleeding complications that must be balanced carefully. Although randomized trials have demonstrated the reduction of ischemic events with GP IIb/IIIa inhibitors in patients who undergo PCI for non-ST elevation acute coronary syndromes and ST-elevation myocardial infarction, bleeding complications are also increased.

Explanations:
The principal haemostatic mechanism is believed to be via extrinsic pathway which is assessed by PT.

Explanations:
Hemostasis means prevention & arrest of bleeding from a cut vessel.

Explanations:
The time required for coagulation to take place is known as the prothrombin time. The shortness of the time is determined mainly by the prothrombin concentration. The normal prothrombin time is about 12 seconds.

Explanations:
The normal range for INR in a healthy person is 0.9 to 1.3. A high INR level (e.g., 4 or 5) indicates a high risk of bleeding, whereas a low INR (e.g., 0.5) suggests that there is a chance of having a clot. Patients undergoing warfarin therapy usually have an INR of 2.0 to 3.0.

Common anticoagulants used in laboratory :
1. 3.8% sodium citrate or oxalate 
2. Potassium oxalate
3. Paul Heller's mixture                                   
(1.2 gm ammonium oxalate + 0.8% potassium oxalate+100ml distilled water) 
4. Heparin
5. Warfarin
6. Normal saline
7. Dicumarol
8. EDTA