Thyroid hormones factors modifying

The effect of thyroid hormones on oxidative processes has long been considered to be their most fundamental action in adult mammals. In 1895, Magnus-Levy made the classic observation that respiratory exchange is depressed in hypothyroidism and elevated in hyperthyroidism. Many factors modify the effect of thyroid hormones in the intact animal, such as nutrition, other endocrine secretions, and the general health of the animal (cf. Boothby and Sandiford, 1924 Sundaram el al., 1956 Money, 1956) a consideration of these fa( tors is beyond the scope of this review. It should be noted that the thyroid hormones appear to exert no calorigenic activity in lower vertebrates (cf. Fromm and Reineke, 1956). 

Finally it should be noted that drug metabolism can be modified, often substantially, by a number of factors like animal species, age, sex and strain. Other modifications can be induced by the nutritional status of the animals and hormonal influences. Those of adrenocorticosteroids, thyroid, and insulin are particularly important. 

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