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Serum TSH values are frequently modestly elevated in patients
with nonthyroidal illnesses such as end- stage renal failure, and
titrating L-thyroxine dosages to return TSH values to the
mid-normal range in such patients may result in mild
hyperthyroidism and have cardiovascular and catabolic
consequences. If free T4 methods, other than ultrafiltration, are
used to monitor L-thyroxine therapy in patients with central
hypothyroidism and concurrent nonthyroidal illnesses,
over-therapy may result if the goal is to return free T4 values
to the mid-normal range.
Use of L-T4 or L-T3 therapy in the vast majority of patients with acute and chronic nonthyroidal illnesses or caloric deprivation who do not have demonstrable hypothalamic, pituitary, or thyroid disease, has not been shown to be beneficial and in some instances is detrimental (2,4,12). However, short-term L-T3 therapy may have beneficial effects in patients undergoing cardiothoracic or cardiopulmonary bypass procedures (4,12). Currently, such use of L-T3 therapy should be restricted to patient populations where a beneficial effect has been clearly demonstrated. |
