Hypothyroidism: management
Key points
• initial starting dose of levothyroxine should be lower in elderly patients and those with ischaemic heart disease. The BNF recommends that for patients with cardiac disease, severe hypothyroidism or patients over 50 years the initial starting dose should be 25mcg od with dose slowly titrated. Other patients should be started on a dose of 50-100mcg od
• following a change in thyroxine dose thyroid function tests should be checked after 8-12 weeks
• the therapeutic goal is ‘normalisation’ of the thyroid stimulating hormone (TSH) level. As the majority of unaffected people have a TSH value 0.5-2.5 mU/l it is now thought preferable to aim for a TSH in this range
• there is no evidence to support combination therapy with levothyroxine and liothyronine
Side-effects of thyroxine therapy
• hyperthyroidism: due to over treatment
• reduced bone mineral density
• worsening of angina
• atrial fibrillation
Interactions
• iron: absorption of levothyroxine reduced, give at least 2 hours apart