Hemostasis and Coag Practical Review

• decreased platelet count

• increased white cell count

• giant platelets are accidentally counted as WBCs on an automated counter

how do giant platelets affect the automatic platelet counts?

• ITP

• TTP

• HUS

• DIC

which conditions are associated with thrombocytopenia?

• myeloproliferative disorders

• IDA

• acute blood loss

which conditions are associated with thrombosis?

• aspirin

• vWD

• Glanzmann’s

which conditions are a cause of abnormal platelet function?

• platelets surround neutrophils due to an interaction with EDTA

• platelets satellites falsely decrease the platelet count

• platelet satellites cause automated analyzers to falsely flag the white blood cells as immature

• to correct for platelet satellites, redraw the patient in both an EDTA tube and a Sodium Citrate tube

• the WBC and platelet count from a Sodium Citrate tube must be multiplied times 1.1

• RBC parameters must be done on an EDTA tube

pick true statements about platelet satellitism.

entire large center square

platelets are counted in the

4 large corner squares

White Cells are often counted in the

5 squares within the center square

red blood cells are counted in

refractile

debris is

small dense dark bodies

platelets are seen as

round or oval-like rods

platelets can be (shape)

pearlescent sheen

platelets may have a

decreased

how does platelet satellitism affect platelet count?

unchanged

how does platelet satellitism affect white blood cell count?

unchanged

how does platelet satellitism affect red blood cell count?

increased

how does platelet satellitism affect immature granulocytes?

unchanged

how does platelet satellitism affect MCV?

unchanged

how does platelet satellitism affect MPV?

unchanged

how does platelet satellitism affect hemoglobin?

unchanged

how does platelet satellitism affect neutrophil count?

R3

which flag will display on the cell counter when there is platelet satellitism?

R1

which flag will display when there are platelet clumps or giant platelets?

• Factor I

• Factor II

• Factor V

• Factor VII

• Factor X

which coagulation factors are measured by the PT?

Vitamin K Dependent Factor

Which group of factors is predominantly altered by liver disease?

Factor VII

Which factor is the first to decrease activity due to the onset of liver disease? (it has the shortest half life, 6 hours)

protime

which test is very sensitive to the factor that decreases due to onset of liver disease?

protime

which coagulation test is a sensitive early marker of liver disease?

Factor V and Factor VII

Which factors need to be measured to distinguish between Vitamin K deficiency and Liver Disease?

Factor V and Factor VII

Which factors are reduced in liver disease?

Factor VII

Which factor is reduced in Vitamin K Deficiency?

Falsely prolong

what is the effect of a short draw resulting in incorrect blood to anticoagulant ratio on coagulation testing?

falsely shorten

what is the effect of prolonged application of tourniquet on coagulation testing?

falsely shorten

what is the effect of hemolysis on coagulation testing?

falsely prolong

what is the effect of lipemia on coagulation testing?

falsely prolong

what is the effect of an icteric specimen on coagulation testing?

falsely prolong

what is the effect of a clotted specimen on coagulation testing?

The presence of an inhibitor

A patient has a PT result of 36 seconds. After performing a mixing study, where the patient plasma is mixed 1:1 with normal plasma, the PT does not correct. Which of the following should be suspected?

Thromboplastin, prepared from recombinant tissue factor suspended in Calcium Chloride

what is the reagent used in PT?

Commercial phospholipid and negatively charged particulate activator such as silica, kaolin, ellagic acid, or celite; and calcium is also required as a reagent

what is the reagent used in PTT?

Bovine thrombin

what is the reagent used in fibrinogen tests?

PTT

which coagulation test is used to measure intrinsic pathway?

PT

what coagulation test is used to measure extrinsic pathway?

PT and PTT

what coagulation test is used to measure common pathway?

PT

what coagulation test is used to measure Coumadin (Warfarin) therapy?

PTT

what coagulation test is used to measure heparin therapy?

Mechanical (such as fibrometer)

Which of the following options is the preferred clot detection method if the sample is lipemic?

adjust the amount of anticoagulant to 0.33 mL of sodium citrate

A phlebotomist receives orders to collect samples for coagulation testing on a patient. This particular patient's diagnosis is polycythemia vera, and has a current hematocrit of 65%. What action, if any, during the sample collection process to collect a 5mL sodium citrate tube should be taken to ensure correct coagulation results are reported?

Possible heparin contamination. Request a specimen recollection, specifying if a line draw is used, flush the line with normal saline, and then discard the first 5 mL of collected blood. 

A sample of blood was drawn out of a central line. The PT and PTT are both prolonged prior to beginning any anticoagulation therapy. Which of the following actions would you recommend?

Results are not as expected. Check specimen quality. Request redraw. Investigate the possibility of the presence of Factor VII deficiency or the presence of an inhibitor

The PT on a pre-surgical patient is 40 seconds. Which of the following actions would you recommend?

yes; redraw the patient, could be wrong patient or poor venipuncture

A hospitalized patient on Coumadin has consistently had Protimes of 19-20 seconds. Is this what is expected? Today, the same patient has a protime of 11.4 seconds. What is the best course of action?

1.5-2 times the normal PTT mean

The expected PTT result on a patient receiving heparin therapy is:

• Factor I

• Factor II

• Factor V

• Factor VIII

• Factor IX

• Factor X

• Factor XI

• Factor XII

Which coagulation factors are measured by the PTT?

The CaCl₂ in the PTT reagent activates the cascade and provides Ca++ that was chelated by citrate

Pick the true answer.

Fibrinogen to Fibrin

What does thrombin time directly measure the conversion of?

Fibrinogen

What is cleaved by thrombin?

Thrombin time

What test is prolonged when it bypasses the coagulation cascade?

Heparin therapy, dysfibrinogenemia, DIC

What causes a prolonged Thrombin time?

INR= (patient PT/PT geometric mean of normal)^ISI

Which of the following is the correct formula for calculating the INR value?

The INR is used to compensate for the inherent variation among thromboplastin reagents used for coumadin therapy

Which of the following statements best explains the purpose of the INR?

0.8-1.3

What is the normal INR range?

2-3

What is the INR therapeutic range?

2.5-3.5

what is the INR mechanical heart valve therapeutic range?

>5.0

what is the INR critical range?

true

An INR value greater than 5 is associated with increased risk of hemorrhage and requires immediate “read-back” communication with the clinician who is managing the patient’s care.