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PTH-related protein
Definition
PTH-related protein is a blood test that measures the amount of a protein molecule related to parathyroid hormone, usually to find out why blood calcium is high.
Alternative Names
PTHrp
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
No special preparation is necessary.
How the Test Will Feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the Test is Performed
This test is done to find out whether high blood calcium levels are caused by an increase in PTH-related protein.
Normal Results
No detectable (or minimal) PTH-like protein is normal.
The examples above are common measurements for results for these tests. 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
Increased levels of PTH-related protein with high blood calcium levels is usually caused by cancer.
PTH-related protein is produced by some cancers, including those of the lung, breast, head, neck, bladder, and ovaries, as well as leukemia and lymphoma. High levels of PTH-related protein are the cause of high calcium levels in about two-thirds of cancer patients. This condition is called humoral hypercalcemia of malgnancy (HHM).
Risks
Veins and arteries vary in size from one patient 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 light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
References
Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 28.
Reviewed By: Nancy J. Rennert, MD, Chief of Endocrinology & Diabetes, Norwalk Hospital, Associate Clinical Professor of Medicine, Yale University School of Medicine, New Haven, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
