A parathyroid hormone blood test measures the amount of parathyroid hormone in your blood.
This is important for assessing multiple medical conditions, including problems with calcium in the body.
What Is PTH?
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Parathyroid hormone (abbreviated PTH) is asignaling moleculesecreted from the parathyroid glands.
These are usually four small glands found near the thyroid gland inside the neck.
PTH plays a critical role in the regulation ofcalciumin the body.
These signals work to increase the amount of calcium in the blood in a number of different ways.
For example, it causes the kidneys to eliminate less calcium through the urine.
It also causes more calcium to be absorbed in your intestines.
This raises the amount of calcium in the blood.
This works to bring the blood calcium back into the normal range.
When Is a PTH Test Necessary?
For example, a high PTH can cause too much calcium in your blood (calledhypercalcemia).
People with an abnormally low PTH might have too little calcium in their blood (calledhypocalcemia).
Such individuals might have symptoms like numbness, tingling, and muscle cramps.
However, some people have an abnormal PTH without any additional symptoms.
Monitoring of ongoing medical conditions is another potential reason for a PTH test.
Hyperparathyroidism:Hyperparathyroidism can arise because there is some sort of problem with the parathyroid glands.
Themost common causeresults from damage to the parathyroid gland, for example, fromdamage during surgeryor radiation therapy.
This might be temporary or permanent.
To properly interpret a PTH test, a medical professional typically needs the results from acalcium blood testas well.
This is taken from the same blood sample as the PTH.
Other tests may also be included, depending on the circumstances.
Together with the PTH, they can give a good indication of any potential underlying medical problems.
It is a basic blood test that can be assessed as part of a simple blood draw.
Sometimes there is slight bleeding or bruising at the site of the blood draw.
Some people experience lightheadedness or dizziness as well.
Some people have financial risk/stress when paying for medical tests.
Some medications may increase PTH levels in certain people.
These include steroids, anticonvulsant drugs, some treatments for osteoporosis, and lithium.
Timing:The blood draw itself should only take a few minutes.
You may also want a chance to rest for a bit after the blood draw.
What to wear:It is often helpful to wear a shirt with loose sleeves.
This makes it easier to for your phlebotomist to access your veins.
Food and drink:Fasting is not usually required before a PTH test.
However, if you are having other tests done at the same time, some of those might.
Your healthcare provider can give you specific instructions if needed.
Cost and health insurance:A PTH test is a relatively inexpensive test that is usually covered by insurance.
What to bring:Bring your insurance card.
In addition, bring a list of the medications you are currently taking.
During the Test
Pre-test:Youll probably need to give your information to a receptionist.
In some cases, you may have a medical or insurance form to fill out.
Throughout the test:To perform the PTH test, a healthcare professional needs to take ablood sample.
He or she will first clean the area.
You may be asked to squeeze your fist while your phlebotomist finds a good vein to use.
The needle will be inserted into a vein in your arm.
This usually only hurts for a moment or two.
Dont leave the area until you are feeling completely steady on your feet.
Keep the bandage on the site for at least an hour.
If it starts to bleed again, apply pressure and raise the site above your head until it stops.
You may also need to avoid heavy activities for a few hours.
Interpreting Results
Results are often available within a day or two.
Your test may also indicate whether your PTH is high, normal, or low.
Your results will probably be reported along with your calcium levels, and in some cases, other substances.
This will help your healthcare provider get an idea of potential underlying causes.
If either is abnormal, you are likely to need follow-up studies.
These can help identify any underlying problems.
This might happen, for example, from an adenoma of the parathyroid gland.
You might need imaging studies of your neck so your healthcare provider can examine the gland in more detail.
Usually, the first such test will be an ultrasound of the area.
If necessary, you might need treatment to remove the gland.
For example, certain autoimmune conditions might cause this.
You may need to have follow-up blood tests to pinpoint the cause.
If your calcium is high but your PTH is low, this will also probably require follow-up blood tests.
These will help your healthcare provider figure out the underlying reason your calcium level is high.
Depending on the circumstances, you may need to have a repeat test done.
That can help check that that the treatment is working for you.
Your healthcare provider is the best person to put your results in perspective.
Dont hesitate to ask any questions you have about what the test means and the best follow-up steps.
A Word From Verywell
It can be uncomfortable waiting for the results of medical tests.
take a stab at be patient with the diagnostic process, which may take time.
Remember that, most of the time, an abnormal parathyroid test arises from a treatable problem.
Craven BL, Passman C, Assimos DG.Hypercalcemic States Associated With Nephrolithiasis.Rev Urol.2008;10(3):218-226.
Cormier C.Genetic hypercalcemia.Joint Bone Spine.
2019;4:1. doi:10.21037/jlpm.2018.12.03
Fischbach FT, Fischbach MA.A Manual of Laboratory and Diagnostic Tests.
Wolters Kluwer; 2017.
