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Sulfonamides (Sulfas)

Bactrim, Septra, Trimethoprim

Test Codes

EPIC: LAB6338, Beaker: XSULF, ARUP: 20044

Department

Send Outs

Instructions

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/Draw 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). (Minimum: 0.5 mL)

Rejection Criteria

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

In-Lab Processing

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).

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

Storage

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 Send Outs Laboratory with any questions.

Laboratory

Sent to ARUP Laboratories, Salt Lake City, UT.

Performed

Monday.
Results available in 3-9 days.

Reference Range

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

Test Methodology

Quantitative Colorimetry.

Interpretation

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 Codes

80299

Contacts

Last Updated

10/3/2023