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6.2.1 Hypothyroidism

Formulary choiceLevothyroxine tablets 25micrograms, 50micrograms, 100 micrograms

Initially 100 micrograms (50micrograms if elderly) daily, adjusted in steps of 25-50micrograms every 6 weeks until TSH is within normal reference range. Usual dose 100–150micrograms daily. Where there is cardiac disease, initially 25micrograms daily, adjusted in steps of 25micrograms

Prescribing Notes

  • Refer to NICE guidance on Thyroid disease: assessment and management
  • Prior to treatment, it is important to establish that thyroid stimulating hormone (TSH) is elevated, thus confirming primary hypothyroidism. A normal or low TSH may suggest pituitary or hypothalamic disease for which specialist referral is necessary.
  • TSH should be checked 6 weeks after starting levothyroxine or after any change in dose, then annually once stable.
  • Alteration in levothyroxine absorption may occur with introduction of other medication such as iron and calcium preparations or drugs altering gastric acid, such as proton pump inhibitors. Thyroid function should be checked 6 weeks after starting such treatment.
  • Pregnant women with hypothyroidism should be seen by a specialist for titration of levothyroxine regimens.  Upon confirmation of pregnancy it is recommended that, due to the early increase in levothyroxine requirements, levothyroxine dosage is doubled on Saturdays and Sundays until review by a specialist.
  • Although generic prescribing remains appropriate for the majority of patients, a small proportion report re-emergence of symptoms after switching between levothyroxine products and hence may benefit from consistent prescribing of a specific brand. See MHRA for further information.
  • Liothyronine should only be used on the recommendation of a Health Service endocrine specialist in secondary care; prescribers in primary care should not initiate liothyronine. For further information please see Shared Care Guideline.