Monitoring therapy in patients taking levothyroxine

Article Abstract:

Patients may receive L-thyroxine, sometimes called levothyroxine, as a supplement in cases of goiter or hypothyroidism. Patients with thyroid tumors may receive thyroxine to prevent the pituitary gland from secreting thyroid stimulating hormone (TSH), which can stimulate the growth of the tumor. An important consideration, however, is maintaining the proper dose of thyroxine. Excessive doses of thyroxine may contribute to osteoporosis; fear of this complication may cause physicians to err on the side of lower doses. Laboratory testing can assist the maintenance of more accurate blood levels of therapeutic thyroxine, but it is unclear whether these measurements contribute significantly to the patient's health. Laboratory testing of the pituitary hormone TSH provides a very sensitive indicator of appropriate thyroxine levels. Some clinicians feel that the suppression of TSH marks the limit of the proper dose of thyroxine. The rationale is that the pituitary gland is attempting to reduce the amount of thyroxine, so the proper level must have been surpassed. However, this does not take into account that these functions are occurring a patient who has already developed a thyroid abnormality, and it is uncertain that the pituitary function in these patients is completely reliable. A review of the medical literature indicates that using the sensitive-TSH assay is most beneficial among patients who are given from 100 to 150 micrograms of thyroxine per day. These patients have about a 50 percent chance of having a reduction in their TSH, and thus, a need for a dose adjustment. Patients taking over 250 micrograms per day are virtually certain to have TSH suppressed to undetectable levels; the test is not informative among these patients. The test may also reveal cases of patient noncompliance, as an elevated TSH level might indicate that the patient is not taking the prescribed dose. However, in cases where symptoms persist and the test indicates an appropriate dose of thyroxine, the test result cannot be considered definitive. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Care and treatment, Hypothyroidism, Goiter

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Screening for thyroid disease

Article Abstract:

The effectiveness of screening for impaired thyroid function was assessed in various clinical settings, such as the community, hospitals, and specialized medical centers for the elderly. Community screening was shown to identify thyrotoxicosis, or hyperactivity of the thyroid gland, and hypothyroidism, or decreased thyroid function, in about 0.5 percent of the general population. This approach was most effective for identifying thyroid function disorders in women over 40 years of age, and least effective among younger men. Case-finding, or screening patients visiting a clinic for reasons unrelated to thyroid disorders, was a more effective and less expensive approach for identifying thyroid disorders than the community screening approach. Routine thyroid function testing does not benefit the patient hospitalized for acute or sudden illness, but is useful for patients admitted to specialized geriatric units for disability, failure to thrive, and other problems. Studies show that 2 to 5 percent of patients admitted to geriatric units have thyroid disorders that can be treated. Initial screening tests include the measurement of blood thyroxine, a thyroid hormone, and tests of the hormone thyrotropin, which is released by the pituitary and which activates the thyroid gland. The results show that thyroid function tests are most beneficial for women over 40 years of age identified by case-finding, and for geriatric patients. Thyroid screening may not be cost-effective in community screening programs or for patients hospitalized for sudden medical or psychiatric disorders. (Consumer Summary produced by Reliance Medical Information, Inc.)

Usage, Evaluation, Medical screening, Health screening, Thyroid gland function tests, Thyroid function tests

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Screening for thyroid disease: an update

Article Abstract:

There is still disagreement over whether or not screening for thyroid dysfunction during the course of an office visit is appropriate, it may be indicated as useful at least for women of 50 yeas old. Because the test for thyroid-stimulating hormone (TSH) is quite sensitive, it could identify women with symptoms not yet presumed to be caused by thyroid disorder. The question as to whether or not treatment is useful can only be answered by screening and trials.

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