T4: thyroxine; TSH: thyroid-stimulating hormone; ULN: upper limit of normal.
* Assumes adherence to medication regimen.
¶ There is an age-related shift toward higher TSH concentrations in older patients (≥70 years), with a ULN of approximately 7.5 mU/L in 80 year olds. Older patients with a TSH up to 7.5 mU/L may not require a dose increase, and treatment resulting in TSH levels under 1 mU/L should be avoided.
Δ Switching between levothyroxine manufacturers does not usually necessitate remeasuring TSH. We typically reserve remeasuring TSH for those concerned about efficacy or if it is important to maintain the serum TSH within a narrow range (eg, thyroid cancer treatment).
◊ Symptoms of hypothyroidism may include cold intolerance, fatigue, constipation. Symptoms of hyperthyroidism may include palpitations, heat intolerance, tremulousness. Refer to UpToDate topics on clinical manifestations of hypothyroidism and hyperthyroidism.Do you want to add Medilib to your home screen?