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Fluoxetine Level (including Norfluoxetine)

Prozac, Fluoxetine (Prozac)

Test Codes

Antrim #16960, EPIC: LAB5390, SOFT: FLUOX

Department

Toxicology

Specimen Collection Criteria

Collect: One plain Red-top tube. (Minimum Whole Blood: 2.0 mL)

Do not use Serum Separator Tubes.
Time of Collection: Trough, just prior to the next dose.
Record the exact time of specimen collection on the tube or in the computer system.

Physician Office/Draw Specimen Preparation

Let specimens clot 30-60 minutes. Centrifuge specimen to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum: 0.5 mL serum)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL serum)

Rejection Criteria

• Serum Separator (SST) tubes.
• Severely lipemic or hemolyzed specimens.

In-Lab Processing

Let specimens clot 30-60 minutes. Centrifuge specimen to separate serum from cells. Deliver immediately to the appropriate testing station.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Frozen (-20°C/-4°F or below): 2 months

Laboratory

Royal Oak Toxicology Laboratory

Performed

Tuesday, Wednesday, Friday.
Routine results available the same day as testing performed (1-4 days).

Reference Range

100-1100 ng/mL (Fluoxetine + Norfluoxetine).
Combined levels above 2000 ng/mL will be called.

Test Methodology

Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS).

This test was developed and its performance characteristics determined by Beaumont Health. It has not been cleared or approved by the FDA. The Laboratory is regulated under CLIA as qualified to perform high-complexity testing. This test is used for clinical purposes and should not be regarded as investigational or for research.

Interpretation

Fluoxetine is converted to an active metabolite. Metabolism can vary widely between individuals. Measurement of both substances is necessary to assess clinical affect. Ideally, dosage should be titrated to affect. Drug concentrations can be helpful in determining the adequacy of a clinical trial.

Clinical Utility

Fluoxetine (Prozac®) is indicated for the treatment of depression and in patients with obsessive-compulsive disorder. This assay is used to monitor the therapeutic drug level and evaluate the toxicity of fluoxetine.

CPT Codes

80299 (alternate: G0480).
LOINC: 10339-0

Contacts

Last Updated

1/19/2023