Theophylline

Pathology category

Biochemistry

Code

THEO

Referral code

Request form

Test information

Used to monitor treatment level of drug

Guidelines

Pre-analytical

Plasma-theophylline concentration is measured 5 days after starting oral treatment and at least 3 days after any dose adjustment. A blood sample should usually be taken 4–6 hours after an oral dose of a modified-release preparation (BNF)

Reference range

In most individuals, a plasma-theophylline concentration of 10–20 mg/litre (55–110 micromol/litre) is required for satisfactory bronchodilation, although a lower plasma-theophylline concentration of 5–15 mg/litre may be effective. Adverse effects can occur within the range 10–20 mg/litre and both the frequency and severity increase at concentrations above 20 mg/litre. (BNF)

Tube type

Tube type info

SST

Special requirements

Serum

Minimum volume

Assay frequency

TAT Inpatient (urgent)

TAT Inpatient

4 hrs

TAT GP/Outpatient

24 hrs

Referral lab

Local, Clinical Biochemistry