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Alternative names, keywords |
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Samples required |
● Clotted blood (gold cap, 5 mL tube). Smaller tubes are available for paediatric samples. Oral use: Take samples 4-6 hr post dose for oral modified-release preparations. Take samples at least 5 days after starting oral treatment, and at least 3 days after dose adjustment. (Source: BNF September 2025) Intravenous use: refer to local guidance. |
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Test indications |
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Factors affecting test performance/ results |
No significant interference from theobromine up to 20 μg/mL. Concentrations above this toxic level may result in negative bias of >10 %. In very rare cases, gammopathy, in particular type IgM (Waldenström’s macroglobulinemia), may cause unreliable results. Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings. |
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Reference range |
Therapeutic range: 10 - 20 mg/L A lower concentration (5 - 15 mg/L) may be effective in some individuals. Adverse effects can occur within the 10 - 20 mg/L range, increasing in frequency and severity above 20 mg/L. (Source: BNF September 2025) |
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Turnaround time |
RSCH same day (within 1h if urgent), PRH 24h (4h if urgent). |
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Enquiries |
Biochemistry (Automation) |