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Test Code 510 Theophylline (Aminophylline)

Important Note

Human anti-mouse antibodies (hama) may be present in samples from patients who have received immunotherapy or diagnostic procedures utilizing monoclonal antibodies or in individuals who have been regularly exposed to animals. Additionally, other heterophile antibodies, such as human anti-goat antibodies may be present in patient samples. Manufacturers formulate assays to minimize the effects of these antibodies; however careful evaluation of patient results must be done when patients are known to have such antibodies.

Additional Codes


PowerChart: Theophylline Level

MA Cerner: Theophylline.

Specimen Requirement

0.5 mL serum or plasma is required.

Additional Specimen Collection Information

Collect blood in a lithium heparin, green-top or red-top tube. Serum and plasma gel tubes are not acceptable.

  • Suspected toxicity specimens are collected when symptoms appear.
  • Acute therapy specimens are collected 30 minutes following I.V. loading dose and again at 4-8 hour intervals.
  • Peak specimens should be collected at least 2 hours after last dose for plain uncoated tablet and liquids; 4 hours after oral dose for sustained release prducts. 

Serum or plasma should be separated from contact with the cells within 2 hours of collection. Specimens not centrifuged within 4 hours of collection may be rejected. Refrigerate the specimen if unable to assay within 8 hours of collection. Samples with >3+ lipemia must be cleared prior to analysis.

Useful For

Assessing and adjusting dosage for optimal therapeutic level

Assessing toxicity


Monday through Sunday

Routine: Typically completed within 4 hours after arrival at the testing site.

Expedite: Typically completed within 1 hour after specimen arrives at the testing site.

STAT: Typically completed within 30 minutes after specimen arrives at the testing site.

CPT Code Information

80198 Therapeutic Drug Levels: Theophylline

LOINC Code Information

4049-3 Theophylline [Mass/Volume] In Serum Or Plasma

Test Method

Turbidimetric Inhibition Immunoassay; Beckman DXC880i

Reference Values

Therapeutic: 8-20 mcg/mL

  • Critical Value: > 20 mcg/mL