The Parathyroids

Fig.1: Indian rhinocerosThe parathyroid glands (usually four in number) are located in the neck behind the thyroid and are involved in the control of blood calcium levels in the body. They secrete one principal hormone, parathyroid hormone (PTH).

They were first discovered during dissection of an Indian rhinoceros (Fig. 1) at London Zoo by Sir Richard Owen, hence the fondness of parathyroid surgeons for this handsome animal pictured here!

It is important to note that although they have similar sounding names, the thyroid and parathyroids are not related, except as neighbours.

They are both parts of the endocrine gland system, the control system of the body, but their hormones have entirely different functions. Unlike thyroid hormone which acts quite slowly, parathyroid hormone has a very quick effect on the body, changing the calcium level in the bloodstream within minutes. PTH is involved in a complex web of interactions that maintains very tight control over the calcium levels, reflecting the vital importance of calcium in the body (see Function).

This Parathyroid section of the website covers all aspects of the parathyroids, including their  anatomy, function and the history of parathyroid surgery. The major diseases affecting the parathyroids can be studied in more detail on their own webpages; just click on the areas of the menu to the left that interest you.