Parathyroid Hormone
Category:
Parathyroid Hormone (PTH), Intact
Description
A parathyroid hormone (PTH) blood test measures the level of parathyroid hormone in blood. This test is used to help identify hyperparathyroidism or to find the cause of abnormal calcium blood levels. PTH controls calcium and phosphorus levels in the blood.
PTH is made by the parathyroid glands. If the blood calcium level is too low, the parathyroid glands release more PTH . Then bones release more calcium into the blood and reduces the amount of calcium released by the kidneys into the urine. Then, vitamin D is converted to a more active form, causing the intestines to absorb more calcium and phosphorus. If the calcium level is too high, the parathyroid glands release less PTH, and the whole process runs opposite direction.
PTH levels that are too high or too low can cause problems with the kidneys and bones and cause changes in calcium and vitamin D.
Tests for calcium and phosphorus levels in the blood are normally done at the same time as a PTH test.
PTH concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the test
This test is done in order to:
- Help identify hyperparathyroidism.
- Find the cause of abnormal blood calcium level.
- Check whether a problem with the parathyroid glands is causing the abnormal calcium level.
- Check problems in people with chronic kidney disease.
Reference range values
10-65 ng/L
Abnormal findings
High PTH levels can be caused by:
- Parathyroid gland growth (hyperplasia) or Parathyroid tumor.
- Low level of calcium in the blood, 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 of the lung, kidney, pancreatic, or ovarian cancer.
Low PTH levels can be caused by:
- Damage to the parathyroid gland, which can by caused by neck surgery or radiation treatments.
- Rare disease, such as sarcoidosis or histiocytosis X.
- Overdose of vitamin D or calcium.
- Cancer, such as lymphoma or multiple myeloma.
- Low magnesium level.