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Beaumont Laboratory

Theophylline Level

Aminophylline, Theodur, Slo-phyllin, Theophylline Level, Serum, Antrim #17140, EPIC: LAB5419, SOFT: THEO

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube. (Minimum Whole Blood: 1.0 mL)
Also acceptable (not preferred): One Gold-top SST tube.

See Minimum Pediatric Specimen Requirements for Microtainer® collection.
Time of Collection: Peak, 2 hours post oral dosing.
Record the exact time of specimen collection on the tube or in the computer system.

Physician Office/Drawsite Specimen Preparation

Let specimens clot 30-60 minutes and refrigerate (2-8°C or 36-46°F) the collection tube within two hours of collection. (Min: 1.0 mL blood)

Preparation for Courier Transport

Transport: Collection tube, refrigerated (2-8°C or 36-46°F). (Min: 1.0 mL blood)

Rejection Criteria

  • Severely lipemic or hemolyzed specimens. 


Specimen Stability for Testing:

Collection Tubes
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 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:

Refrigerated (2-8°C or 36-46°F): 7 days


Farmington Hills Chemistry Laboratory.
Grosse Pointe Chemistry Laboratory.
Royal Oak Toxicology Laboratory.


Sunday - Saturday, 24 hours a day.
STAT results available within 1 hour of receipt in the Laboratory.
Routine results available within 24 hours.

Reference Range

Therapeutic Range: 10-20 mcg/mL.
Critical Range: Greater than 25 mcg/mL.

Test Methodology

Enzyme Immunoassay.


Theophylline metabolism may be increased by infections and metabolic inducers such as Phenytoin and Phenobarbital. Its metabolism may be decreased by metabolic inhibitors such as Erythromycin.

Clinical Utility

Theophylline is a naturally occurring compound with bronchodilator effects. It is used in the treatment of bronchospasm associated with bronchial asthma, chronic bronchitis and pulmonary emphysema. This assay is used to monitor the therapeutic drug level and evaluate the toxicity of theophylline. Due to the drug's narrow therapeutic range and the wide personal variation in the rate of metabolism and clearance, essentially every patient taking theophylline should have their serum levels monitored.

CPT Code


Test Codes

Antrim #17140, EPIC: LAB5419, SOFT: THEO

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.