Parathyroid Hormone (PTH) Test Test
This test measures the level of parathyroid hormone (PTH) in your blood. PTH controls calcium levels in your blood, which is important for your nerves, muscles, and heart to work properly.
What this test measures
This test measures the level of parathyroid hormone (PTH) in your blood. PTH is made by your parathyroid glands, four pea-sized glands in your neck. PTH controls the level of calcium in your blood.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
If your PTH level is higher than normal, it's called hyperparathyroidism. There are two types: Primary hyperparathyroidism (high PTH with high blood calcium) often means a problem with your parathyroid glands, such as a benign tumor. Secondary hyperparathyroidism (high PTH with low blood calcium) means your parathyroid glands are working correctly to try to increase low blood calcium, likely due to a problem outside the glands.
Lower-than-normal results
If your PTH levels are lower than normal and your blood calcium level is also low, it may mean your parathyroid glands can't make enough PTH. This is called hypoparathyroidism. Possible causes include damage to the glands from surgery or radiation, autoimmune disorders, or genetic disorders.
Frequently asked questions
What is a PTH test used for?
A PTH test is used to help find out whether parathyroid disorders are the cause of abnormal blood calcium levels, help find the cause of low phosphate levels, monitor people with chronic kidney disease, help find the cause of severe osteoporosis, and check whether treatment for a parathyroid disorder is working.
How does PTH control calcium levels?
PTH raises blood calcium by telling your bones to release calcium, helping your intestines absorb calcium from food, and helping your kidneys keep calcium in your blood instead of getting rid of it through urine.
What is primary hyperparathyroidism?
Primary hyperparathyroidism is high PTH levels with high blood calcium levels. This often means a problem with your parathyroid glands is causing them to make too much PTH. The most common cause is a benign tumor called a parathyroid adenoma.
What is secondary hyperparathyroidism?
Secondary hyperparathyroidism is high PTH levels with low blood calcium levels. Your parathyroid glands are working correctly by making extra PTH to try to increase your blood calcium. It's likely a problem outside the glands, such as low vitamin D or kidney failure.
What is hypoparathyroidism?
Hypoparathyroidism is when PTH levels are lower than normal and blood calcium is also low. It means your parathyroid glands can't make enough PTH. Possible causes include damage from neck surgery, autoimmune disorders, or genetic disorders like DiGeorge syndrome.
Related lab tests
Sources
- MedlinePlus: Parathyroid Hormone (PTH) Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.