How often should I monitor TSH levels in a patient who is stable on levothyroxine therapy for hypothyroidism?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 14 August 2025Updated: 14 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

For a patient who is stable on levothyroxine therapy for hypothyroidism, thyroid-stimulating hormone (TSH) levels should be monitored annually once stability is confirmed by two similar TSH measurements within the reference range taken 3 months apart.

Initially, TSH should be measured every 3 months until the level stabilises (defined as two similar measurements within the reference range 3 months apart). After this, annual monitoring is recommended.

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