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Test Code DILFX or LAB32 Dilantin Level, Free, Serum

Important Note

Due to consumable backorder, these tests are being routed to our Mayo Reference Laboratory. Please order a miscellaneous test for PNYF. PNYF can be found in the lab test catalog. 

Specimen Requirements

Container Type:

Acceptable: Red

 
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:

1 mL whole blood
Collection Instructions:

1.  Specimen should be drawn just prior to next dose (trough level).

2. A minimum of 2 hours prior to next dose is also acceptable.

3. Indicate time of last dose.

4. Gently invert the sample 5-6 times after collection.
Specimen Transport:

Refrigerate
Processing Instructions: 

1. Allow the specimen to clot for 30 minutes.

2. Centrifuge specimen within 2 hours of collection.

3. After centrifugation, specimen tubes without a gel barrier should have the serum aliquoted to a false bottom container.

4. Keep the serum refrigerated until testing can be performed.

Specimen Stability

Specimen Type Temperature Time
Serum Refrigerated 4 days
Room Temperature 24 hours
Frozen 2 weeks

Specimen Rejection Criteria

Hemolysis Mild OK; Moderate OK; Gross Reject
Lipemia Mild OK; Moderate OK; Gross Reject
Icterus Mild OK; Moderate OK; Gross Reject
Other Quantity not sufficient

Useful For

This assay is useful for monitoring free Dilantin therapy.

Methodology

Roche Cobas - Kinetic interaction of microparticles in a solution (KIMS)

Reference Ranges

Therapeutic range: 1.2-2.5 ug/mL

 

Critical Value: > 3.0 ug/mL

Interpretive

PNYF - Clinical & Interpretive: Phenytoin, Free, Serum (mayocliniclabs.com)

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo

Sample Retention Time

7 days

CPT Code

80186

LOINC Code

3969-3