Hypothyroidism - Resources

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T3 and T4 Combinations. Triiodothyronine (T3), the other important thyroid hormone, is not ordinarily prescribed except under special circumstances. Most patients respond well to thyroxine (T4) alone, which is converted in the body into T3. In addition, the use of T3 may cause disturbances in heart rhythms. Some patients treated only with thyroxine continue to have mood and memory problems or other symptoms.

Combination products containing T4 and T3, such as liotrix (Thyrolar), are available, but there is some controversy concerning their benefits. Several recent studies have indicated that, although some patients may prefer combination therapy, T3 and T4 together do not work better than T4 alone. Patients might like the combined drugs because they cause more weight loss, or a placebo effect may be involved. It does not appear that combination products offer any advantage for normalizing TSH levels.

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Levothyroxine Regimens

Levothyroxine needs to be taken only once a day. It is slowly assimilated by body organs, so it usually takes up to 6 weeks before symptoms improve in adults. Nevertheless, many patients feel better after 2 - 3 weeks of treatment. The speed at which specific symptoms improve varies:

• Weight loss, less puffiness, and improved pulse usually occur early in the treatment.
• Improvements in anemia and skin, hair, and voice tone may take a few months.
• High LDL ("bad" cholesterol) levels decline very gradually. HDL ("good" cholesterol) levels are not affected by treatment.
• Goiter size declines very slowly, and some patients may need high-dose thyroid hormone (called suppressive thyroid therapy) for a short period.

Levothyroxine reduces blood pressure in about half of hypothyroid patients with hypertension, although blood pressure medications may still be needed.

Appropriate Dosage Levels. Initial dosage levels are determined on an individual basis and can vary widely, depending on a person's age, medical condition, other drugs they are taking, and, in women, whether or not they are pregnant. For example, pregnant women with hypothyroidism may need higher than normal doses.