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Beaumont Laboratory

Sulfonamides (Sulfas)

Bactrim, Septra, Trimethoprim, ARUP #20044, EPIC: LAB6338, SOFT: XSULF


Indicate which sulfa drug is being administered.

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.
Also acceptable: One Lavender-top EDTA tube.

Do not use Serum Separator Tubes.

Time of Collection: Peak, 2 hours post dose.

Physician Office/Drawsite Specimen Preparation

Centrifuge to separate serum or plasma from cells within two hours of collection. Transfer serum or plasma to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 1.0 mL serum or plasma, refrigerated (2-8°C or 36-46°F). (Min: 0.5 mL)

Rejection Criteria

  • Serum Separator (SST) tubes.
  • Specimens not collected and processed as indicated.


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 14 days
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 14 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Sendout Laboratory with any questions.


Sent to ARUP Laboratories, Salt Lake City, UT.


Tuesday, Friday.
Results available in 2-6 days.

Reference Range

Therapeutic: 5.0-15.0 mg/dL.
Toxic: Greater than 20.0 mg/dL.

Test Methodology

Quantitative Colorimetry.


Peak Sulfonamide blood levels of 5-15 mg/dL may be considered effective for most infections, concentrations of 12-15 mg/dL being optimal for serious infections. Sulfonamide levels should not exceed 20 mg/dL.

Clinical Utility

Sulfonamides are used in the treatment of urinary tract infections, often in combination with trimethoprim, as well as otitis, bronchitis, sinusitis, and pneumocystic pneumonia. This assay is used for the therapeutic monitoring and toxicity assessment of sulfonamides (Sulfas).

CPT Code


Test Codes


Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.