Laboratory Flashcards
What is the purpose of Neoplastin
starting reagent for PT that contains a heparin inhibitor made of rabbit brain, helps ID factor deficiencies
What are the contents and purpose of PTT reagent. **
contains-CaCl, starting reagent for PTT test
What test is for evaluating the intrinsic pathway?
PTT
What test is for evaluating the extrinsic pathway
PT
What test can be used to evaluate the functioning of the common pathway
both PT and PTT
What is the mechanism of heparin
binds to anti-thrombin to form a complex, inhibits Xa
How is the therapeutic range of heparin determined
PTT will be 2-3x normal when pt is on heparin
What test is used to monitor heparin therapy
PTT
What protein accelerates the effects of heparin
AT3
What neutralizes the effects of heparin
protamin sulfate
What is the action of coumadin
its an oral anticoagulant that affects the vitamin K dependent factors
What factors are vitamin K dependant
2,7,9,10
What neutralizes coumadin
vitamin K
What test is used to monitor coumadin
PT
Why is coumadin overlapped with heparin therapy
they overlap for 5-7 days because protein C levels drop in this time period and the pt is at risk of throwing a clot
What is the INR
the standardized PT standardized thromboplastin across the country and world
What is the formula for the INR
patients PT/ mean PT of population
What is the ISI, how is it determined
international sensitivity index, calculated by manufacturer with each lot of STA neoplastine- changes once a year
What is the PTT reference range
23.5-32.9
What is the INR range for pts on coumadin
2-3
What kind of plasma do routine specimen have
plt poor plasma
What is the centrifuge time and speed for coag specimen
10 min
3000rpm
What is the reason a coag tube should be completely full
9:1 ratio of coagulant vs blood
What are 2 reasons a coag specimen will be rejected
clotted
QNS
What does an increased hematocrit do to PTT results
if higher than 55%, PTT increases, less plasma in tube, less factors, clot takes longer
What mechanism does the anticoagulant in blue top tubes use, which anticoagulant is it
sodium citrate, binds Ca, prevents clot from forming
What methodology does the STAR MAX use
mechanical for detecting clot times
What should you do if QC fails on STAR MAX
rerun QC. if still bad makeup new reagents, if still bad- rerun patients and make new reagents again
if still bad, recalibrate
What is the principle of Clauss FBG, what is the purpose of diluting the specimen
measures the amount of FBG through clotting method Clauss. quantitative test
dilutions are to keep value in range of what the instrument can read- within linearity
What is the normal range for FBG
200-400
What disease states cause FBG to be low
DIC, fibrinogenolysis, hypofibrinogenemia
What disease states cause BG to be high
DIC, diabetes, obesity
pregnancy or trauma- really high
What coag tests are normally ordered for a pt that has just delivered a baby
PTT, PT, FBG
What is the principle of the D-dimer test
photometry measures particles that coat monoclonal D-dimer abs, quantifies D-dimer present by turbidity
increased agglutination=increased turbidity = increased absorbance= increased D-dimer abs
The presence of D-dimer is proof that the _____system is in action
fibrinolytic
What disease states cause an elevated D-dimer
covid, fibrinolysis, infections, bleeding, VTW
What fibrin split products are early degradation? Which ones are late degradation products?
early-X and Y
late- D and E
What coag factor splits fibrin products
plasmin
What is the principle of FDP/ FSP testing
Test that measures latex beads that coat abs against D and E, which are late products of X and Y, measured agglutination
What disease states are associated with increased FSP/FDP
DIC, increased fibrinolysis,
DVT 10-40,
pulmonary embolism higher than 40,
myocardial infarction 40-160
snake bites
pregnancy complications, hemolytic anemia, transfusion rxns
What tube is FSP performed with
FDP vacutainer with atrox venom a rapid clotting promoter that works even if heparin is present
specimen must clot before centrifuging
What is the principle of the thrombin time test
measures the time it takes to convert
FBG into fibrin, tests clotting time, functionality of FBG
What are the 2 inhibitors that affect TT?
heparin increases TT
hirudin, argatroban
What conditions cause an elevated TT?
DIC, dysfibrinogenemia
hypofibrinogenemia- congenital or acquired by liver disease
ant thrombin medication like heparin
What is the difference between FBG and TT?
FBG- measure amount of FBG present
TT- measures functionality of FBG
If FBG is low. TT will be high
What if the principle of a PFA
platelet function test- measures quality of aggregation and plts
What does it mean if in a PFA, both EPI and ADP are abnormal?
indicates pt has VWD or Glanzmann’s thrombastenia
What does it mean if in a PFA, EPI is abnormal but the ADP is normal
aspirin is causing plt inhibition
What is the mechanism of aspirin
it binds to arachidonic acid and cyclo oxygenase
What do factor assays measure
clotting time for specific factors
What is the principle of the P2Y12 Assay?
detects the P2Y12 inhibitor that inhibits plavix a stroke/ heart disease medication
If an assay result is too high even after being diluted, then the patient has a
factor deficiency
What is the most common hemophilia and what factor is deficient in it
VIII
Hemophilia A
How quickly should a mixing study correct
within 5 seconds
If a mixing study correct then the pt has a
factor deficiency
If a mixing study doesnt correct, the pt has a
inhibitor
What is CACS
circulating anticoagulant screen
inhibitors are the circulating anticoagulants here
What is the most commonly found factor inhibitor
anti-VIII
IF a pt has a factor inhibitor, what will the results of the mixing study be
will stay prolonged
What is the unit in which factor inhibitors are expressed
Bethesda
What is the principle of TEG
a large test that measures full coag cascade, measures clot formation
What test is ordered for HIT
heparin induced thrombocytopenia
an assay that measures abs to heparin
What is the role of VWF
a carrier protein for factor VIII
What test results for DIC
FBG
PT, PTT and TT
D-dimer
plt count
FBG decreases
PT, PTT and TT increase- takes longer to clot
D-dimer and FSP increase
plt count decreases
factors and plts are eaten and destroyed, takes longer time to form clot
Which one is affected by diet? and body weight?
coumadin
heparin
coumadin- not affected by body weight, is affected by diet
heparin- affected
What are the main reasons we do coag testing
diagnose:
Myocardial infarctions
Deep vein thrombosis
Strokes- ischemic and hemorrhagic
pulmonary embolism
Which test tube binds to Ca- reversible and irreversible
EDTA
Sodium citrate
EDTA- irreversible
sodium citrate- reversible
How soon must a sodium citrate tube be spun, what temp should it be at
within 8hrs, room temp
What are some main reasons coag specimen get rejected
hemolysis, WNS, clotted, Delayed transportation
What are the HCT requirements in coag and why do we care
must be >55% causes prolonged tests
What is the formula to obtain HCT from a CBC EDTA tube
(60/ 100-pt HCT) x 4.5
Match the instrument and reagents used in these tests
PT
PTT
TT
FBG
D-Dimer
PT- Neo and KOH desorb
PTT- PTT, CaCl, Desorb KOH
TT- thrombin, desorb
FBG- FBG, OK buffer, KOH
D-dimer- latex particle with anti- human D-dimer, TRIS buffer
What is a critical value for a PTT
> 200 secs or less than <20
What is cephalin
a plt substitute
What might interfere with a PTT result
heparin therapy especially if high PF4
What are the common causes of factor deficiencies?
Liver disease
DIC
Fibrinolysis
Autoimmune disorders- lupus
heparin or anticoagulant therapy
thrombin inhibitors
What is the TT reference range
15.4-18
What factor deficiency will not prolong a TT
factor XIII
When is a TT necessary
if PT or PTT is abnormal but unexplained
What does an abnormal TT indicate
dysfibrinogenemia
Which is susceptible to lipemia, which isnt
otpical detection- sucseptible
mechnical- not affected
What are the clinical uses of a PFA
preoperative
menorrhagia evaluation
drug indcuced plt dysfunction
pt compliance with aspirin and other antiplt drugs
determining if high risk pregnancy
pts with suspected VWD
What are in the ADP and EPI cartridges for a PFA and why
collagen- in both, plts adhere to it start coag cascade
EPI-epinephrine
ADP- adenosine diphosphate
What is the normal range for EPI? and ADP?
EPI- 98-172
ADP-50-132
How long is the half life of FBG
3-5 days
What does TPA do
tissue plasminogen activator- degrades fibrin
What neutralizes plasmin
alpha 2 antiplasmin
What is fibrin cleaved into
D-dimer and FDP
What is the normal D-dimer range
<0.50
How is FDP testing performed
Thrombo Welllcotest Kit
What are the normal results for Anti-Xa assay
0
What does Xa do
cleaves prothrombin into thrombin, creates fibrin
Why is the Anti-Xa assay performed
to measure LMWH and UFH
What pts do not need FFP
pts with no coagulation deficiencies or active bleeds
What does it mean if after a mixing study, the results become prolonged again after 1-2 hrs
indicates factor VIII inhibitor
How is Hemophilia A inherited
affects males on X chromosome, F carriers are silent
What factor deficiency is associated with Ashkenazi jews
Facotr XI
What factor deficiency is not associated with any bleeding problems
facror XII deficiency
What factor deficiency is a very rare disorder
factor XIII
What are Lupus anticoagulants
abs directed against phospholipids and protein complexes
What does it mean if a pt has a prolonged PTT with a protein C assay
cant stop the activation of Va and VIIIa
What does protein C do
inhibit factor V and VIII
What inhibits protein C
alpha 1 antitrypsin
What activates protein C
agkistrodon contortix vemnon
What does protein S do
antagonistic to coagulation, cofactor for protein C
What consequences can protein S deficiencies cause
chronic inflammation, hepatic disorders, nephrotic syndrome, thromboembolism
How is HIT tested for
ELISA testing detects abs for PF4 that complexes with heparin
What blood type tends to have less VWF
group O
What tube is needed for plt mapping
green top
What does the TEG activator do
Kaolin
TF
Heparinase
maximizes thrombin generation time
kaolin- starts intrinsic pathway
TF- activates extrinsic pathway
What do these terms mean in TEG
R
K
Alpha
MA
G
CI
LY30
EPL
R clotting time
K and alpha clot kinetics
Ma and G clot strength
CI coagulation index
LY30, EPL- clot stability
What does a hemorrhagic TEG look like
thinner longer fork
LY30 CI and R show that there are low clotting factors
What does a hypercoagulopathy TEG look like
Fat fork, prothrombic state due to enzymes and plt hyperativity
What does an increased fibrinolytic TEG look like
sensei legs, excess of tPA and plasmin
What is a DIC
disseminated intravascular coagulation- systemic or body wide clotting, multiple organ failure
