High Molecular Weight Kininogen (HMWK)
Also known as: Fitzgerald Factor, HMWK
Use
Useful in the evaluation of an elevated aPTT. Measurement of high molecular weight kininogen concentration
Special Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Ensure the tube is filled properly to maintain the correct blood to anticoagulant ratio. The sample must be mixed immediately by gently inverting the tube at least six times. Plasma must be transferred into a Labcorp PP transpak frozen purple tube with a screw cap immediately after centrifugation, and kept frozen until testing. Separate frozen specimens are suggested if multiple tests are ordered on frozen samples.
Limitations
Contact factor deficiencies like HMWK deficiency do not result in bleeding consequences but can prolong aPTT in lab settings. The test is specific for diagnosing HMWK deficiency, which is inherited in an autosomal recessive manner. Increased aPTT can also be due to deficiencies in factors XII, prekallikrein, and HMWK. This test's results are for research purposes as the assay's performance characteristics have not been fully established by the manufacturer. Confirmatory diagnostics should be conducted using another medically established procedure.
Methodology
Chromosomal / Cytogenetics (Clot-based)
Biomarkers
LOINC Codes
- 52754-9
Result Turnaround Time
4-8 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
2 mL
Minimum Volume
1 mL
Container
Blue-top (sodium citrate) tube
Collection Instructions
Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Ensure proper mixing of blood with anticoagulant by gently inverting the tube immediately at least six times.
Patient Preparation
Do not draw from an arm with a heparin lock or heparinized catheter.
Storage Instructions
Freeze; stable at room temperature for four hours.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 hours |
| Frozen | Acceptable for four freeze/thaw cycles. |