There remains some controversy in the literature and in clinical practice about the merits of replacing both T3 and T4 versus T4 alone . At present, there are few good randomized controlled clinical studies that have examined this issue in large numbers of patients. For an overview of this topic, see a discussion on controversies Optimal Thyroid Hormone Replacement. As thyroid hormone has a long half life, it takes 3-4 weeks for a new steady state level of thyroid hormone to equilibrate in the blood. Hence retesting too early after initiation of thyroxine may give inaccurate results.
Many patients taking thyroid hormone are concerned about the possibility of Osteoporosis .
The individual risk factors for osteoporosis in each patient should be reviewed with your physician. Nevertheless, many patients with normal levels of thyroid hormone are concerned about osteoporosis and their thyroid status, and these concerns may often be alleviated by briefly reviewing the evidence linking thyroid disease and osteoporosis . Simply put, in patients taking thyroxine who have normal levels of TSH, there is no evidence linking physiological thyroid hormone replacement with an increased risk of osteoporosis. Although treatment of hypothyroid patients who have heart disease may increase energy and cardiac function, treatment must be initiated slowly, and low doses of thyroid hormone should be used. Many patients with significant degrees of hypothyroidism may have a reduced heart rate, and occasionally reduced function of the heart due to the lack of the beneficial action of thyroid hormone on the heart muscle.