THEOPHYLLINE - serum

---

Specimen: 5 mL blood in plain tube.

Method: Immunoassay, HPLC.

Therapeutic Interval:

Neonate:	33-66 µmol/L (6-12 mg/L)
Child, adult:	55-110 µmol/L (10-20 mg/L)

Application: Monitoring theophylline therapy.

Interpretation: 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.

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

---