Parathyroid hormone-related protein blood test
The parathyroid hormone-related protein (PTH-RP) test measures the level of a hormone in the blood, called parathyroid hormone-related protein.
PTHrp; PTH-related peptide
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No special preparation is necessary.
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 sensation. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
This test is done to find out whether a high blood calcium level is caused by an increase in PTH-related protein.
No detectable (or minimal) PTH-like protein is normal.
Women who are breastfeeding may have detectable PTH-related protein values.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
An increased level of PTH-related protein with a high blood calcium level is usually caused by cancer.
PTH-related protein can be produced by many different kinds of cancers, including those of the lung, breast, head, neck, bladder, and ovaries. A high level of PTH-related protein is the cause of a high calcium level in about two-thirds of cancer patients. This condition is called humoral hypercalcemia of malignancy (HHM).
Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- 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. Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 13th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 28.
Thakker RV. The parathyroid glands, hypercalcemia and hypocalcemia. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 245.
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.