Which drugs can lower TSH without inducing true thyroid dysfunction?
Another interesting, but rare cause of hyperthyroidism is so-called hamburger thyrotoxicosis. Both types of disease are relatively common afflictions of man and animals. The half-life of amiodarone is extremely long, and elimination from adipose tissue may take several months.
Curr Opin Endocrinol Diabetes. Excellent concise review. In times past, consumption of dessicated animal thyroid gland was used for the same purpose. Carbohydrate metabolism: Thyroid hormones stimulate almost all aspects of carbohydrate metabolism, including enhancement of insulin-dependent entry of glucose into cells and increased gluconeogenesis and glycogenolysis to generate free glucose. Symptoms of IFN-induced hypothyroidism or hyperthyroidism may be difficult to distinguish from the side-effects of IFN therapy. The effect of the hormone-receptor complex binding to DNA is to modulate gene expression, either by stimulating or inhibiting transcription of specific genes.
In some cases, thyroid gland atrophy is seen. The most severe and devestating form of hypothyroidism is seen in young children with congenital thyroid deficiency.
Common symptoms of hypothyroidism arising after early childhood include lethargy, fatigue, cold-intolerance, weakness, hair loss and reproductive failure. J Clin Endocrinol Metab.. There have been some reports of a correlation between cancer response to sunitinib and the occurrence of hypothyroidism.
In euthyroid amiodarone-treated patients, the T4 and FT4 concentrations are high normal or slightly increased and the T3 and FT3 concentrations are in the lower range of normal. In iodine-deficient areas, iodine supplementation used to prevent endemic goiter has been associated with an increase in the incidence of hyperthyroidism. Transcription of some myosin genes is stimulated by thyroid hormones, while transcription of others in inhibited. They also promote vasodilation, which leads to enhanced blood flow to many organs. A number of plasma membrane transporters have been identified, some of which require ATP hydrolysis; the relative importance of different carrier systems is not yet clear and may differ among tissues.
Which drugs can cause thyroid dysfunction and should this be treated? Excellent review with recent evidence. Monitoring of thyroid function will allow the clinician to assess whether the hyperthyroidism is transient or more permanent. In most species, this condition is less common than hypothyroidism. In times past, consumption of dessicated animal thyroid gland was used for the same purpose.
Primary thyroid disease: Inflammatory diseases of the thyroid that destroy parts of the gland are clearly an important cause of hypothyroidism. Most cases of hypothyroidism are readily treated by oral administration of synthetic thyroid hormone. Common signs of hyperthyroidism are basically the opposite of those seen in hypothyroidism, and include nervousness, insomnia, high heart rate, eye disease and anxiety. As lithium is primarily used in the treatment of bipolar disorder, hyperthyroidism should be considered in the differential diagnosis during manic or anxious episodes. In humans the most common form of hyperthyroidism is Graves disease, an immune disease in which autoantibodies bind to and activate the thyroid-stimulating hormone receptor, leading to continual stimulation of thyroid hormone synthesis.
An exception is bexarotene, in which the associated central hypothyroidism that is occasionally seen normalizes after the discontinuation of the medication. Hyperthyroidism results from secretion of thyroid hormones. Growth: Thyroid hormones are clearly necessary for normal growth in children and young animals, as evidenced by the growth-retardation observed in thyroid deficiency. Iodine-containing medications and agents Exogenous iodine administration from topical disinfectants, radiologic contrast agents, amiodarone, and other sources can induce hyperthyroidism or hypothyroidism. Physiologic Effects of Thyroid Hormones It is likely that all cells in the body are targets for thyroid hormones.
Not surprisingly, the growth-promoting effect of thyroid hormones is intimately intertwined with that of growth hormone , a clear indiction that complex physiologic processes like growth depend upon multiple endocrine controls. Singh, N, Hershman, J. For additional details on mechanism of action and how these receptors interact with other transcription factors, examine the section Thyroid Hormone Receptors.