The PTH test measures the level of parathyroid hormone in the blood.
PTH stands for parathyroid hormone. It is a protein hormone released by the parathyroid gland.
A laboratory test can be done to measure the amount of PTH in your blood.
Parathormone; Parathormone (PTH) intact molecule
How the Test is Performed
A blood sample is needed. For information on how this is done, see: Venipuncture
How to Prepare for the Test
Ask your health care provider if you should stop eating or drinking for some period of time before the test. Most often, you will not need to fast or stop drinking.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
Parathyroid hormone (PTH) is released by the parathyroid glands. The four tiny parathyroid glands are located in the neck, near or attached to the back side of the thyroid gland. PTH controls calcium, phosphorus, and vitamin D levels in the blood. It is important for regulating bone growth. Your health care provider may order this test if:
You have a high calcium level or low phosphorus level in your blood.
You have severe osteoporosis that cannot be explained or does not respond to treatment.
To help understand whether your parathyroid hormone level is normal, your doctor will measure your blood calcium at the same time.
Normal values are 10 to 55 picograms per milliliter (pg/mL).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different specimens. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
A higher-than-normal level may occur with:
Disorders that increase phosphate or phosphorous levels in the blood, such as chronic kidney disease
Failure of the body to respond to parathyroid hormone (pseudohypoparathyroidism)
Lack of calcium, which may be due to not eating enough calcium, not absorbing calcium in the gut, or losing too much calcium in your urine
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.