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Parathyroid hormone test
Make it clearer
This test measures how much parathyroid hormone, or PTH, is in the blood. It is made by the parathyroids, four pea-sized glands in the neck. And their job is to control the calcium in the blood.
The circuit is easy to picture. When blood calcium drops, the parathyroids release just enough hormone to bring it back to normal. It works like a thermostat for calcium: it switches on when the level drops. And it raises calcium in two ways: it tells bone to release calcium into the blood, and it helps the intestine absorb calcium from food.
That is why the number is never read on its own. Because the amount of hormone changes with calcium, a blood calcium level is almost always ordered along with it. It also helps determine whether a parathyroid disorder explains a calcium result that came back abnormal.
In brief
The test measures blood parathyroid hormone, which controls calcium and is made by the four parathyroid glands in the neck.
When calcium drops, the parathyroids release just enough hormone to bring it back to normal: they tell bone to release calcium and they help the intestine absorb it.
It works like a thermostat for calcium: it switches on when the level drops.
Because the level depends on calcium, the test is almost always ordered with a blood calcium level, to see whether a parathyroid disorder explains the result.
Sources (1)
- MedlinePlus, U.S. National Library of MedicineParathyroid Hormone (PTH) Test, MedlinePlus Medical TestPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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