plasma mixing studies
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Introduction
A set of tests in which the patient's plasma is mixed with plasma from a healthy individual or with pooled plasma.
Indications
Principle
- addition of normal plasma to the patient's plasma will correct a deficiency in a coagulation factor, whereas will have less if any effect on a coagulation factor inhibitor
- the PT may correct initially after mixing, but not after 1 hour of incubation
* excess phospholipid is added to the patient's plasma & the aPTT corrects is consistent with antiphospholipid syndrome[3]
Interpretation
- mixing studies correct PT & aPTT for
- aPTT does not correct for coagulation factor inhibitor
- acquired hemophilia A (factor VIII inhibitor)[2]
- correction of aPTT without correction of PT (after incubation) suggests inhibitor of coagulation factor VIIA
- 'correction' is an ambiguous term
- complete correction of aPTT would imply aPTT < 35 seconds
- a correction of aPTT from 85 seconds to 48 seconds or 90 seconds to 45 seconds is only a partial correction & is consistent with a coagulation factor inhibitor[1]
More general terms
References
- ↑ Jump up to: 1.0 1.1 Medical Knowledge Self Assessment Program (MKSAP) 16, 17 American College of Physicians, Philadelphia 2012, 2015
- ↑ Jump up to: 2.0 2.1 2.2 Geriatric Review Syllabus, 11th edition (GRS11) Harper GM, Lyons WL, Potter JF (eds) American Geriatrics Society, 2022
- ↑ Jump up to: 3.0 3.1 NEJM Knowledge+ Hematology