Test ID: 


CPT code:



Aminophylline, Blood
Elixophyllin® Elixir

Clinical Use:

Theophylline is used in the treatment of bronchial asthma as well as in the treatment of chronic obstructive pulmonary disease and episodes of prolonged apnea in pre-term infants. Theophylline levels are monitored to assure adequate therapeutic levels are achieved and to avoid toxicity.

Test Information:

Theophylline is prescribed for bronchial asthma, for chronic obstructive pulmonary disease, and for newborn apnea. The drug is extensively metabolized with peak serum levels reached four hours after oral dose. Troleandomycin and erythromycin may slow theophylline elimination. Heart failure, liver disease, prolonged fever, certain infections, and obesity may have similar effects. Prolonged half-life occurs in premature infants. Dosage should be reduced in these situations.
By contrast, half-life is shortened in smokers, variable with phenobarbital administration; higher doses are also tolerated in acidemia. Smokers on the average are reported to need 1.5 to 2 times as much of the drug as nonsmokers to achieve the same effects. Optimal resampling time after change in dosage is 48 hours for adults, one to two days for children. The half-life of theophylline is from 3 to 10 hours for adults and 1.4 to 7.9 hours for children, but varies between individuals.
Studying serum concentrations and toxic effects, Bertino et al found toxicity with peak theophylline concentrations as low as 19.4 mg/L. Recognizing theophylline toxicity over a wide range of theophylline levels, these authors questioned the association between the severity of toxic effects and serum concentrations. Aitken and Martin also found lack of correlation between serum theophylline level and toxic effects
Blood levels should be interpreted in light of the patient’s clinical status and use of other medications.
Toxic effects include nausea, vomiting, diarrhea, headache, atrial and ventricular arrhythmias, tremors, and convulsions.

Specimen Type:

Serum or plasma

Requested Volume: 

1 mL

Minimum Volume: 

0.3 mL

Container Type: 

Red-top tube or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.


Transfer separated serum or plasma to a plastic transport tube. Trough: immediately prior to next dose; after change in dose: children: two days, adults: one to two days

Storage Instructions:

Room temperature

Stability Requirements:



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x2

Expected Turnaround Time:

1 to 2 Days

Rejection Criteria

Gel-barrier tube; hemolysis; gross lipemia; icteric specimen

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MCI Diagnostic

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Sun: 7AM-3PM

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Sun: 7AM-3PM


Mon – Sat: 7AM-11PM

Sun: 7AM-3PM

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