Theophylline - serum

Last updated: Tuesday, 30, March, 2004

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Item Process

5 mL blood in plain tube.

Preferably collected pre-dose; timing of post-dose peak varies with formulation.


Immunoassay, HPLC.

Therapeutic Interval

Neonate: 33-66 µmol/L (6-12 mg/L)

Child, adult: 55-110 µmol/L (10-20 mg/L)


Monitoring theophylline therapy.


During acute illness, the half-life may be prolonged beyond the usual range of 3-9 hours.

Toxicity may develop if the dosage is not reduced. Toxicity may occur within the therapeutic interval in some patients.

Cigarette smoking reduces the half-life and therefore decreases levels significantly.


Glynn-Barnhart A et al. Drugs 1988; 35: 711-726.