The PTH blood test is used to determine the amount of parathyroid hormone that is present. PTH is a protein hormone that is released by the parathyroid gland. There are actually 4 tiny glands located in the neck, attached to or near the thyroid gland, and this protein hormone controls calcium levels in the blood.

PTH also works to control phosphorus levels and vitamin D levels that are in the blood. It helps to regulate bone growth when it is present at normal levels. If there are abnormal levels of PTH in the blood, then this will generally be reflected by the presence of abnormal calcium levels.

For most providers, testing for calcium is a common blood test offered during an annual checkup. By detecting high or low levels of calcium, it can be determined if a PTH blood test will be required as a follow-up.

When Will the PTH Blood Test Be Ordered?

The PTH blood test is ordered whenever there are high calcium levels, low calcium levels, or low phosphorus levels that have been detected in previous tests. It may also be ordered for individuals who may be suffering from osteoporosis that will not respond to treatments. Certain individuals who have been diagnosed with kidney disease may also have this blood test ordered for them.

A calcium blood test will often be ordered at the same time as the PTH blood test. This occurs even if a previous calcium test was ordered and is the trigger for an evaluation of PTH levels.

What Do My PTH Blood Test Results Mean?

Most PTH blood test results will be communicated as being “normal” or “abnormal.” A normal PTH result is usually between 10-55 pg/mL. Anything falling outside of that range would be considered by most medical providers as being an abnormal result.

When results are higher than 55 pg/mL, then this may be an indication that there is a disorder present that is affecting phosphorous or phosphate levels within the body. This is most often seen with a condition like chronic kidney disease.

It can also be an indication that the body is failing to respond to PTH in some way.

There may also be a lack of calcium in the blood for some reason. The cause of this may be something as simple as not eating enough foods that contain calcium. It may also be a reflection of a malabsorption issue that is related to calcium. Some individuals may have too much calcium being expelled from the body for some reason.

Certain vitamin disorders can also cause abnormally high PTH blood test results. The most common form of this issue is a lack of vitamin D production, which happens when there isn’t enough sunlight exposure.

Low PTH blood test results are common after someone has their parathyroid glands removed for some reason. The destruction of the glands, such as occurs sometimes because of an autoimmune disorder, may also cause test results to be lower than 10 pg/mL.

Certain cancers have also been known to affect the bones and this can alter PTH results. This includes cancers that have metastasized and spread to the bones from other parts of the body.

More commonly, however, an abnormally low level of PTH is caused by taking an excessive amount of calcium over a long period of time. This occurs when individuals are taking certain antacids on a regular basis or may be consuming too many calcium supplements. It is also caused by having low levels of magnesium in the blood or an excessive amount of vitamin D being taken through supplements.

Here’s What You Need to Know

It is possible to have an abnormal PTH blood test result, but not actually experience any symptoms from this health issue. This is seen when calcium levels slowly change over time instead of rapidly changing. For this reason, the calcium testing tends to happen before PTH testing because calcium levels in the blood are easy to detect and manage.

Some medical providers may choose to test for vitamin D before testing for calcium or PTH. This is because the vitamin is necessary for the body to absorb calcium in a proper way. PTH will then regulate the activation of vitamin D, which regulates the metabolism. If there isn’t enough vitamin D, then you won’t get enough calcium even though you might be through diet choices and supplements.

The PTH blood test can help a medical provider determine the functionality of the parathyroid glands while also observing potential health issues. Contact your doctor today if you think this blood test might benefit you.