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Parathyroid hormone (PTH) blood test

Parathormone; Parathormone (PTH) intact molecule; Intact PTH; Hyperparathyroidism - PTH blood test; Hypoparathyroidism - PTH blood test

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.

How the Test is Performed

A blood sample is needed.

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

PTH is released by the parathyroid glands. The 4 small parathyroid glands are located in the neck, near or attached to the back side of the thyroid gland. The thyroid gland is located in the neck, just above where your collarbones meet in the middle.

PTH controls calcium, phosphorus, and vitamin D levels in the blood. It is important for regulating bone growth. Your provider may order this test if:

To help understand whether your PTH is normal, your provider will measure your blood calcium at the same time.

Normal Results

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 provider about the meaning of your specific test results.

What Abnormal Results Mean

A higher-than-normal level may occur with:

A lower-than-normal level may occur with:

Other conditions for which the test may be ordered include:

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

Related Information

25-hydroxy vitamin D test
Calcium blood test
Chronic kidney disease
Hyperparathyroidism
Malabsorption
Osteomalacia
Rickets
Magnesium deficiency
Hypoparathyroidism
Bone tumor
Milk-alkali syndrome
Sarcoidosis
Multiple endocrine neoplasia (MEN) II
Multiple endocrine neoplasia (MEN) I

References

Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 28.

Chernecky CC, Berger BJ. Parathyroid hormone (PTH) - Blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:854-856.

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Review Date: 11/17/2017  

Reviewed By: Brent Wisse, MD, board certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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