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Thyroid test timing — GPhC CRA MCQ

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HardEndocrine TherapeuticsThyroid test timingGPhC CRA

Levothyroxine was increased two weeks ago in an otherwise stable adult. They are asymptomatic and ask for TSH testing tomorrow to decide whether another increase is needed. What is the best monitoring plan?

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Correct answer: E — Wait at least six weeks after the dose change for routine TSH testing

TSH responds slowly to levothyroxine dose changes, so SPS recommends testing from six weeks after initiation or a dose change and then continuing at suitable intervals until stable. A routine test at two weeks can mislead and prompt inappropriate escalation. Free T3 and serum levothyroxine concentrations are not substitutes for standard TSH-guided monitoring, while waiting six months would delay titration unnecessarily.

Reference: SPS: levothyroxine monitoring. https://sps.nhs.uk/monitorings/levothyroxine-monitoring/