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Thyroid hormones induce catabolism by enhancing proteoanabolism
Take the tadpole tail: it is catabolized (resorbed) at the moment when
the thyroid hormones start to act in a metamorphosing tadpole (becoming
a frog). On the other hand, the human brain needs thyroid hormones for
its development - a clearly anabolic effect. The thyroid hormones are indispensable
for proteosynthesis and development in surplus; they are, however, catabolic
and produce tissue wasting, as in Graves-Basedow's disease. It is relatively
easy to explain this controversy by thyroid-hormone stimulation of the
proteosynthesis of catabolically acting enzymes. But important questions
remain. Take the bones: an excess of thyroid hormones leads to bone wasting,
to osteoporosis. This is an important problem in the treatment of hypothyroidism
in the menopausal age. Question: does not the thyroid gland, forecasting
the detrimental effect of its hormones on the bone, start to produce calcitonin?
Is there a link between hyperthyroidism and calcitonin secretion? We all
know that calcitonin is a physiological antagonist of parathyroid hormone:
but is it not also an antagonist of T3?
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