Mixing Studies Flashcards
a process which is used to determine the missing factors or problems in plasma/serum
a process which is used to determine the missing factors or problems in plasma/serum
MIXING STUDIES
patient plasma is mixed with normal pooled plasma and test(s) is(are) repeated
MIXING STUDIES
indicates a factor deficiency (hereditary, or acquired causes such as warfarin therapy or liver disease)
• shortening of the time into the reference range (correction)
indicates a circulating inhibitor (heparin, lupus inhibitor, VIII inhibitor, IX inhibitor)
• partial or no correction
used interchangeably with
factor assays
:part of the testing process to determine the specific cause of an unexpected, prolonged PT or aPTT
factor assays
performed when the (?) is prolonged to differentiate the
PT (E/CP) or aPTT (I/CP)
cause:
• coagulation factor deficiency (most common)
• specific factor inhibitor
• nonspecific/circulating inhibitor (usually in immunocompromised individuals)
primary purpose: to determine the
deficient coagulation factor
used to confirm a suspected factor deficiency, as suggested by a mixing study that shows correction
FACTOR ASSAY
measures the ability of patient plasma to correct the PT or aPTT result obtained with plasma known to be factor deficient (compared to known standards)
FACTOR ASSAY
done through mixing studies
FACTOR ASSAY
performed after mixing studies have been performed and a deficiency of one or more coagulation factors is suspected
FACTOR ASSAY
performed after mixing studies have been performed and a deficiency of one or more coagulation factors is suspected
FACTOR ASSAY
done through mixing studies
FACTOR ASSAY
PROCEDURE
mix equal parts of (?) then repeat the prolonged test
patient plasma + fresh normal plasma
RESULTS AND INTERPRETATIONS
(?) the prolonged test
repeat
remains prolonged
NOT CORRECTED
NOT CORRECTED may be due to the presence of the following:
• circulating anticoagulants
• specific factor inhibitors
• mixing sample
lupus anticoagulant targeting V and X → [DRRVT])
• circulating anticoagulants
autoantibodies that target specific factor (e.g. (?) → [BETHESDA Test])
• specific factor inhibitors
FVIII inhibitor
inappropriate sample used
• mixing sample:
due to factor deficiencies in patient’s plasma thus corrected upon the addition of fresh normal plasma
CORRECTED
CORRECTED next step (identification of deficient factor):
• identify the deficient factor by performing (?)
additional mixing study or factor assay
CORRECTED
• procedure: mix equal parts of (?)
patient’s plasma + an appropriate mixing sample)
Fresh plasma FACTORS PRESENT
all factors
Fresh plasma FACTORS ABSENT
Aged plasma FACTORS PRESENT
all (w/exception)
Aged plasma FACTORS ABSENT
V, VIII
Fresh serum FACTORS PRESENT
Prothrombin gp. (II, VII, IX, X)
Contact gp.(XI, XII, PK, HMWK)
Fresh serum FACTORS ABSENT
Fibrinogen gp. (I, V, VIII, XIII)
Aged serum FACTORS PRESENT
Prothrombin gp. (w/exception)
Contact gp.
Aged serum FACTORS ABSENT
Fibrinogen gp., II
BaSO4 adsorbed plasma FACTORS PRESENT
Fibrinogen and contact group
BaSO4 adsorbed plasma FACTORS ABSENT
Prothrombin group
BaSO4 adsorbed serum FACTORS PRESENT
Contact group
BaSO4 adsorbed serum FACTORS ABSENT
Prothrombin and fibrinogen group
PT:
VII, TF
APTT:
VIII, IX, XI, XII
PT and APTT:
X, V, II, I
I
APTT: P
PT: P
II
APTT: P
PT: P
III (TF)
IV (calcium)
V
APTT: P
PT: P
VII
APTT: N
PT: P
VIII
APTT: P
PT: N
IX
APTT: P
PT: N
X
APTT: P
PT: P
XI
APTT: P
PT: N
XII
APTT: P
PT: N
XIII
APTT: N
PT: N
PT: normal
APTT: prolonged
corrected by fresh serum but not adsorbed plasma
POSSIBLE DEFICIENT FACTORS:
• prolonged APTT: VIII, IX, XI, XII
• fresh serum: IX, XI, XII
• adsorbed plasma: VIII, XI, XII
MISSING FACTOR: IX
PT and APTT: prolonged
Corrected by: Fresh serum
Not corrected by: Adsorbed serum
POSSIBLE DEFICIENT FACTORS:
• Prolonged PT/APTT: I, II, V, X
• Fresh serum: II, VII, IX, X
• Adsorbed serum: no II, VII, IX, X, I, VIII, XIII
MISSING FACTOR: II or X (perform confirmatory tests e.g., TT, RVVT)
PT: prolonged
APTT: normal
Corrected by: normal plasma and adsorbed serum
Not corrected by: adsorbed plasma
POSSIBLE DEFICIENT FACTORS:
• prolonged PT: TF, VII
MISSING FACTOR: VII (TF does not cause prolonged PT/APTT; cannot be corrected by any substitution)
