In the stable elderly patient, it is recommended to
begin therapy at a low synthetic T4 dose of 25 µg daily and increase the dose by
25- to 50-µg increments every 4 to 6 weeks, based on results of the TSH test.
Checking a TSH level before 4 weeks have passed is likely to show a falsely elevated
level. A sudden increase in levothyroxine may place excessive strain on the patients
cardiac reserve. The TSH level, not the T4 level, is used as the metabolic marker.
The goal of treatment is to normalize, not suppress, the TSH level. In patients with
central hypothyroidism, the T4 level is monitored because the cause of the
hypothyroidism is a low TSH level. This condition usually occurs as a result of
postpartum pituitary necrosis (Sheehans syndrome) or a pituitary tumor.
- Initial dose of 25 µg daily, titrated every 4 to 6 weeks to achieve a
normal serum TSH level.
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Seminars in Medical Practice
Hospital Physician Board Review Manuals
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Updated 1/04/08 kkj