Possible mechanisms of TSH--independent thyroid growth.

Considerable evidence has been accumulated which indicates the participation of the autonomic nervous system in the growth of adrenals, ovaries, testes and thyroid lobes. Results have been gathered indicating that the pituitary is not required for the growth of the thyroid, adrenals and ovaries; interest is currently focused on the involvement of the pineal gland in the control of growth not only of the gonads, but also of the thyroid. This paper summarizes the data currently available on the concepts of thyroid hypertrophic and hyperplastic mechanisms, which occur independently of thyrotropin (TSH), and which suggest the existence of a reciprocal relationship between the pineal and the thyroid.