| Primary
Name |
Partial
Thromboplastin Time Mixing Study |
| Synonym |
Partial
Thromboplastin Time Mixing Study |
| Synonym |
Partial
Thromboplastin Time Substitution |
| Contraction |
APTT
Mix |
| Contraction |
PTT
Mix |
| Contraction |
PTT
Substitution |
| UAB
Procedure Number |
2500168 |
| CPT
Code |
85732 |
| Specimen |
Collect one (1)
blue-stopper tube (3.2% sodium citrate), filled to specified volume.
Do not underfill or overfill.
|
| Specimen
Management |
Centrifuge
blue-stopper tube within 1 hour of collection, separate
plasma and test or quick-freeze at -70°C. |
| Specimen
Accepted |
Daily
including weekends |
| Times
Available |
All
times |
| Test
Performed |
All
times |
| Available
Stat? |
Yes |
| Description |
An
APTT mixing study is indicated when the APTT is prolonged in the absence
of heparin therapy. Patient plasma is mixed with normal plasma and the
APTT is repeated. If the mixture's APTT result does not correct, the patient
may have an inhibitor. There are specific inhibitors such as anti factor
VIII, associated with bleeding, and lupus anticoagulants, associated with
thrombosis. If the mixture's APTT result does correct, the patient may
have a coagulation factor deficiency. The results of the APTT mixing study
are used to direct further studies in consultation with the ordering physician. |
| Reference
Interval |
*
Correction suggests factor deficiency.
*No correction suggests presence of an inhibitor. |
| Critical
Value |
-- |
| Therapeutic
Range |
-- |
| Follow-up
Test |
*
If APTT corrects, follow up with factor assays.
*If APTT does not correct, follow up with lupus anticoagulant testing.
*An incubated mixing study may be ordered with pathologist's approval. |
| Associated
With |
Coagulation
factor inhibitors |
| Associated
With |
Bleeding
disorders |
| Associated
With |
Venous
thrombosis |
| Associated
With |
Lupus
anticoagulant |
