Parathyroid hormone (pth) test

A test for parathyroid hormone (PTH) is done to:

• Help identify hyperparathyroidism.
• Find the cause of an abnormal blood calcium level.
• Check to see whether a problem with the parathyroid glands is causing the abnormal calcium level.
• Watch for problems in people who have chronic kidney disease.

A health professional uses a needle to take a blood sample, usually from the arm.

In general, there's nothing you have to do before this test, unless your doctor tells you to.

Results are usually available in 1 to 2 days.

Normal

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

High values

High PTH levels may be caused by:

• A parathyroid gland growth (hyperplasia) or a parathyroid tumor.
• A low level of calcium in the blood. A low blood calcium level can be caused by kidney disease, kidney failure, severe vitamin D deficiency, or an inability of the intestines to absorb calcium from food.
• Some types of cancer, such as lung, kidney, pancreatic, or ovarian cancer.

Low values

Low PTH levels may be caused by:

• Damage to the parathyroid gland, which can by caused by neck surgery or radiation treatments.
• A rare disease, such as sarcoidosis or histiocytosis X.
• An overdose of vitamin D or calcium.
• Cancer, such as lymphoma or multiple myeloma.
• A low magnesium level.