MMSC423 - Hematology I Exam 2

Normal range for Bleeding Time (BT)

2-9 minutes

Normal range for PFA-100

• Collagen/EPI: 78-199 seconds

• Collagen/ADP: 53-137 seconds

Normal range for Prothrombin Time (PT)

12.6 - 14.6 seconds

TNR is 2-3

Normal range for APTT

25-35 seconds

APC-Resistance ratio

>/= 2.0

Fibrinogen Assay

200-400mg/dL

Thrombin Time

</= 21 seconds

D-Dimer

110-240 mg/dL

Diseases in which BT increases (prolonged BT)

vWD, Bernard-Soulier syndrome, Glanzmann’s thrombasthenia, Afrinogenemia

ISI

international sensitivity index

PT evaluates

extrinsic and common pathway (no factor 13)

APTT evaluates

intrinsic and common pathway (no factor 13)

relationship between % transmittance and platelet aggregation in platelet aggregometry studies

higher platelet aggregation = more light transmittance

Test to monitor Coumadin therapy

PT

Test to monitor Herapin therapy

APTT & FXA assay

Calculate % aggregation based on Plateletworks assay

% Aggregation = (Baseline PLT-Agonist PLT)/(Baseline PLT) x 100

Blood to anticoagulant ration required for the PT and APTT

1 part sodium citrate to 9 parts whole blood

Lupus Anticoagulant

• IgG or IgM immunoglobin directed towards phospholipids, which are used in the APTT test

• Inhibits formation of the prothrombinase complex

• patients will have prolonged APTT

TEG: increased R (reaction time) result

• 0 - 2mm

• normal: 5-10 minutes

• decreased clot formation

• treated with fresh frozen plasma (FFP)

TEG: increased K (coagulation time) result

• end of R - 20 mm

• normal: 1-3 minutes

• deficient fibrinogen

• treat with cryoprecipitate

cryoprecipitate includes

fibrinogen, vWF, VIII, XIII

TEG: decreased Alpha Angle (speed of fibrin accumulation)

• normal: 53 -72 degrees Celsius

• deficient fibrinogen

• treat with cryoprecipitate

TEG: decreased MA (Maximum Amplitude)

• normal: 50-70 mm

• deficient platelets

• treat with platelets

TEG: increased LY30

• normal: 0-8%

• hyperfibrinolysis

• treat with antifibrinolytic (tranexemic acid and/or aminocaproic acid)

Factor V Leiden

• normally protein C degrades factors Va & VIIIa

• patients with this mutation resist factors Va & protein C binding, thus factor V cannot degrade

Pre-analytical Coagulation Testing

• patient preparation

• sample collection

• specimen handling & transport

Analytical Coagulation Testing

• test methodology

• calibration & quality control

• interference

• instrumentation

Post-analytical Coagulation Testing

• result interoperation

• reporting & documentation

• follow up & action

Reflex Testing

when an initial screening test is performed → abnormal results are found → secondary confirmatory test is then performed

example: mixing study

TT

Thrombin Time

RT

Reptilase Time

Afibrinogenemia

• increased TT

• increased RT

• fibrinogen → undetectable

Hypofibrinogenemia

• increased TT

• increased RT

• fibrinogen → low

Dysfibrinogenemia

• increased TT

• increased RT

• fibrinogen → low/normal

Heparin

• increased TT

• normal RT

• fibrinogen → increased

Reactive Thrombocytosis

• elevation in platelet count with no change in platelet function

• caused by a disease or condition

Causes of Reactive Thrombocytosis

• acute blood loss

• splenectomy

• childbirth

• chronic inflammatory disease

• infection

• iron deficiency anemia

• malignancy

NAIT

• neonatal immune-mediated thrombocytopenia

• mother lacks a platelet-specific antigen that the fetus has inherited from the father and makes antibodies against it which attack the fetus

• IgG antibodies cross the placenta and attach to antigen -bearing fetal platelets, resulting in thrombocytopenia in the fetus

• treated with IVIG and platelet transfusions

PTP

• post-transfusion pupura

• rare disorder that typically develops about 1 week after transfusion of platelet-containing blood products

• severe thrombocytopenia, hemorrhage, petechia, and purpura

• decreased platelet count

• treated with IVIG

Thrombocytopenia

condition that occurs due to low platelet count in the blood

HIT

• heparin induced thrombocytopenia

• 5% of patients develop IgG antibody for heparin-PF4 complex

• those antibodies congregate into complexes that bind onto platelet Fc receptors

Platelet satellitosis & protocols to resolve CBC results

• platelets surround a neutrophil

• course of action: redraw the patient using sodium citrate

• repeat CBC using a correction factor 1.1 for WBC and platelet counts

Therapeutic range of INR

• INR = (patient PT/control PT) ^ ISI

• range for patients on Coumadin: 2-3

Coumadin

anticoagulant (blood thinner)

APC-Resistance Test

• a type of APTT-based test measured with addition of APC in the numerator

• Ratio = (patient clot time with calcium chloride & APC / Patient clot time with calcium chloride)

• Ratio: >/= 2.0

Name a vivo test to access platelet function

BT (Bleeding Time)

What does TEG stand for?

Thromboelastography

What effect will a hemolyzed sample have on coagulation tests like PT and APTT?

Shorter time to form a fiber clot because of the release of ADP

This blood product is indicated if the maximum amplitude is low on a TEG analysis:

Platelets

This blood product is indicated if the R Time is increased on TEG analysis:

Fresh Frozen Plasma (FFP)

What does PFA-100 measure?

Closure time (CT)

A mixing study was conducted after the PT and APTT yielded increased results. Which one of these tests constitutes the reflex test?

Mixing study

What sample is needed for APTT? PPP or PRP?

Platelet Poor Plasma (PPP)

PRP (Platelet Rich Plasma) is used for:

platelet aggregation studies

In platelet satellites, what sample is needed to resolve an invalid platelet count?

Sodium Citrate sample

In the fibrinogen assay, is a decreased time in seconds (for clotting) associated with higher or lower fibrinogen levels?

Higher fibrinogen levels

What percentage of platelets are stored in the spleen?

30%

What abnormal RBC morphology is found in DIC?

Schistocytes

True or False: Heparin is never given in DIC?

False

This disorder is caused by a deficiency in ADAMTS13 giving rise to Microangiopathic Hemolytic Anemia (MHA):

Thrombotic Thrombocytopenic Purpura (TTP)