Parathyroid hormone (PTH) blood testParathormone; 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.
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.Read Article Now Book Mark Article
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:
- You have a high calcium level or low phosphorus level in your blood.
High calcium level
Hypercalcemia means you have too much calcium in your blood.Read Article Now Book Mark Article
Hypophosphatemia is a low level of phosphorus in the blood.Read Article Now Book Mark Article
- You have severe osteoporosis that cannot be explained or does not respond to treatment.
Osteoporosis is a disease in which bones become fragile and more likely to break (fracture).Read Article Now Book Mark Article
- You have kidney disease.
To help understand whether your PTH is normal, your provider will measure your blood calcium at the same time.
The calcium blood test measures the level of calcium in the blood. This article discusses the test to measure the total amount of calcium in your blo...Read Article Now Book Mark Article
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. Try to go back to the same lab each time you need to have your PTH level tested so your provider can reliably compare your results over time.
A PTH value in the normal range can still be inappropriate when serum calcium levels are high. Talk to your provider about what your result means.
What Abnormal Results Mean
A higher-than-normal level may occur with:
- Disorders that increase phosphate or phosphorous levels in the blood, such as long-term (chronic) kidney disease
Long-term (chronic) kidney disease
Chronic kidney disease is the slow loss of kidney function over time. The main job of the kidneys is to remove wastes and excess water from the body...Read Article Now Book Mark Article
- Failure of the body to respond to PTH (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
- Pregnancy or breastfeeding (uncommon)
- Swelling or tumors (adenomas) in the parathyroid glands, called primary hyperparathyroidism
Hyperparathyroidism is a disorder in which 1 or more of the parathyroid glands in your neck produce too much parathyroid hormone (PTH).Read Article Now Book Mark Article
- Vitamin D disorders, including not enough sunlight in older adults and problems absorbing, breaking down, and using vitamin D in the body
A lower-than-normal level may occur with:
- Accidental removal of parathyroid glands during thyroid surgery
- Autoimmune destruction of the parathyroid gland
- Cancers that start in another part of the body (such as the breast, lungs, or colon) and spread to the bone (releasing calcium into the blood stream)
- Excess calcium over a long period of time usually from excess calcium supplements or certain antacids, that contain calcium carbonate or sodium bicarbonate (baking soda)
Excess calcium over a long period of ti...
Milk-alkali syndrome is a condition in which there is a high level of calcium in the body (hypercalcemia). This causes a shift in the body's acid/ba...Read Article Now Book Mark Article
- Parathyroid glands do not produce enough PTH (hypoparathyroidism)
Hypoparathyroidism is a disorder in which the parathyroid glands in the neck do not produce enough parathyroid hormone (PTH).Read Article Now Book Mark Article
- Low levels of magnesium in the blood
Low levels of magnesium in the blood
Magnesium deficiency is a condition in which the amount of magnesium in the blood is lower than normal. The medical name of this condition is hypoma...Read Article Now Book Mark Article
- Radiation to the parathyroid glands
- Sarcoidosis and tuberculosis
Sarcoidosis is a disease in which inflammation occurs in the lymph nodes, lungs, liver, eyes, skin, and/or other tissues.Read Article Now Book Mark Article
- Excess vitamin D intake
Excess vitamin D intake
Hypervitaminosis D is a condition that occurs after taking very high doses of vitamin D.Read Article Now Book Mark Article
Other conditions for which the test may be ordered include:
- Multiple endocrine neoplasia (MEN) I
Multiple endocrine neoplasia (MEN) I
Multiple endocrine neoplasia (MEN) type I is a disease in which one or more of the endocrine glands are overactive or forms a tumor. It is passed do...Read Article Now Book Mark Article
- Multiple endocrine neoplasia (MEN) II
Multiple endocrine neoplasia (MEN) II
Multiple endocrine neoplasia, type II (MEN II) is a disorder passed down through families in which one or more of the endocrine glands are overactive...Read Article Now Book Mark Article
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:
- Excessive bleeding
- Multiple punctures to locate veins
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Melmed S, Auchus RJ, Goldfine AB, Koenig RJ, Rosen CJ, eds. Williams Textbook of Endocrinology. 14th ed. Philadelphia, PA: Elsevier; 2020:chap 29.
Klemm KM, Klein MJ, Zhang Y. Biochemical markers of bone metabolism. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 16.
- Hyperparathyroidism(Alt. Medicine)
- Hypoparathyroidism(Alt. Medicine)
- Thyroiditis(Alt. Medicine)
- Vitamin D(Alt. Medicine)
- Kidney stones(In-Depth)
- Osteoporosis(Alt. Medicine)
- Colorectal cancer(Alt. Medicine)
Review Date: 10/18/2021
Reviewed By: Robert Hurd, MD, Professor of Endocrinology and Health Care Ethics, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.