Week 4 - Hematology: clotting and platelet disorders

Question 1

Two Elements to Clotting

Answer 1

Injury to bl vessels > vasodilation to bring bl to the area > platelets stick together with collagen (platelet plug) > Fibrin (a string of protein) needs factor XIII(A)

Question 2

Function, Pathway, and Lab Values:

PT

INR

PTT

Answer 2

PT: 11-13 sec, extrinsic pathway (X, VII, V, II and fibrinogen) Extrinsic way, Warfain

INR: 0.9-1.3 (coumadin 2-3), International Normalized Ratio

PTT: 28-35 sec, Intrinsic Pathways (XII, XI, X, IX, VIII, V, II and Fibrinogen) Intrinsic Pathway

Question 3

Hemophilia

Type

describe bleeding behavior

PTT

PT

Factors

Symptoms and patient education

Answer 3

Hemophilia

• Genetic: X-link recessive, mostly males XY (get from mom); both parents must have disease to get as a female
• still have platelets, just no fibrin
• Type A: 80%, lack factor VIII (don’t have part of positive feedback) A8
• Type B: 15%, lack factor IX (have all of positive feedback, so less serious) B9
• Bleed long, not faster
• Infants bruising with mild irritation.
• Umbilical cord bleeds excessively
• Older noses bleeds easy bruising, blood in urine, severe joint pain, joint surgery
• Labs: Inc PTT, normal PT and bleeding time (normal bleeding time = how fast you bleed out) > bleed out longer
• Testing: Inc PTT, normal PT/BT, Factor 8 or 9

Question 4

Thrombocytopenia

Describe bleeding time

Answer 4

• Low platelet count = bleeding time (faster) goes up

Platelets are the bolders and fibrin is the sand to plug the tinny holes

Question 5

Von Willebrand’s Disease

cause?

Describe bleeding

Answer 5

• Genetic: autosomal dominant
• Don’t have Von Willebrand factor
• Platelets don’t clump together
• vWF is needed to make platelet aggregate and adhere (inadequate platelet plug = prolong bleeding)
• Labs: Incr PTT and bleeding time, but PT and PLT normal
• Positive vWF antigen

Question 6

DIC

describe

causes

labs

Answer 6

• Lots of tissue factor III (Extrinsic pathway) released, which is not normally in blood
• D-dimer goes up
• Widespread clotting > consumes platelets & clotting factors leading to hemorrhage
• Clotting and bleeding at the same time
• Causes: sepsis, bacterial infections, cancer, placenta retained or abruptions, anesthesia, burns, major trauma
• Inc PT, Inc PTT
• Dec PLT, dec fibrinogen
• Inc D-dimer (break down products of fibrin)

Question 7

Steps for Intrinsic and Extrinsic Pathways

Positive Feedback

Negative Feedback

Answer 7

Intrinsic Pathways: Collagen > XII > XI > (IX + VIII) > (X+V) > Thrombin II > (Fibrin 1A + XIII)

Extrinsic Pathway: Tissue Factor III > VII > X + Thrombin II > Fibrin I

Positive Feedback (V, VII, VIII, XI, XIII)

Negative Feedback (Plasmin, Antithrombin > X and II)