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Test Code CARFT Carbamazepine, Free and Total, Serum

Profile Information

Test ID Reporting Name Available Separately Always Performed
CARTA Carbamazepine, Tot, S Yes Yes
CARF Carbamazepine, Free, S Yes Yes

Method Name

CARF: Ultrafiltration Followed by Homogeneous Microparticle Agglutination Immunoassay

CARTA: Homogeneous Microparticle Agglutination Immunoassay

Specimen Type

Serum Red


Specimen Required


Container/Tube: Red top (serum gel/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 2 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Refrigerated (preferred) 7 days
  Frozen  28 days
  Ambient  48 hours

Reject Due To

Gross hemolysis Reject

Clinical Information

Carbamazepine (Tegretol) is an effective treatment for complex partial seizures, with or without generalization to tonic-clonic seizures. It is frequently administered in conjunction with other antiepileptic agents, such as phenytoin and valproic acid.

 

Under normal circumstances, 75% of the carbamazepine that circulates in blood is protein bound. In severe uremia, carbamazepine may be displaced from protein, resulting in a higher free (unbound) fraction of the drug circulating in blood. Since neurologic activity and toxicity are directly related to the circulating free fraction of drug, adjustment of dosage based on knowledge of the free carbamazepine level may be useful in patients with severe uremia.

Reference Values

CARBAMAZEPINE, TOTAL

Therapeutic: 4.0-12.0 mcg/mL

Critical value: ≥15.0 mcg/mL

 

CARBAMAZEPINE, FREE

Therapeutic: 1.0-3.0 mcg/mL

Critical value: ≥4.0 mcg/mL

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 day

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

80156

80157

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.