Return to Test Directory
PHENYTOIN, serum (087-0439)
Test Mnemonic:


Specimen Requirements:


Routine venipuncture. Collect immediately prior to next dose.  Collect 7 mL of blood in red-topped tube. Do not use SST/serum separator tube. (Min: 3 mL of blood).

DO NOT draw blood in SST/gel separator vacutainer tube.


Red-topped tube

Minimum Volume:

3 mL of blood



Delivered to Sample Management within 2 hours of collection.  

Centrifuge specimen within 2 hours after collection. Remove serum from cellular material within 2 hours after collection. Place serum in labeled plastic transport tube. Refrigerate serum aliquot.

Specimen Preparation:


Allow specimen to clot completely at room temperature. Centrifuge to separate serum from cells within 2 hours of collection. Transfer serum from red-topped tube to labeled plastic transport tube. 


Room Temperature for ≤8 hours; Refrigerated for ≤7 days; Frozen for ≤12 weeks

Causes for Rejection:

Blood drawn in SST/gel separator vacutainer tube, incomplete and/or incorrect sample identification, improper storage/transport , gross hemolysis, icterus or lipemia,                                                                                                  

Reference Range:

By report (reports may vary based on instrumentation, patient age and sex).

Turnaround Time:

Routine: 8 hours; ASAP: 4 hours; STAT: 1 hour


Multi-point Immuno-Rate


Clinical Chemistry

CPT 4 Code:


When ordering tests for which Medicare or Medicaid reimbursement will be sought, physicians should only order tests that are medically necessary for the diagnosis or treatment of the patient. Components of the organ or disease panels may be ordered individually. The diagnostic information must substantiate all tests ordered and must be in the form of an ICD-10 code or its verbal equivalent.
Return to Test Directory