What you need to know about the parathyroid hormone (PTH) blood test

You probably already know how important calcium is for keeping our bones and teeth strong. But did you know that calcium, an essential mineral, also needs to be in normal levels to maintain healthy blood vessels, muscles, and the nervous system? If your recent blood test results showed that your calcium levels were either too high or too low, your doctor may have ordered another special blood test. That's the test we're talking about today, which measures your parathyroid hormone (PTH) levels.

Simply put, what is parathyroid hormone (PTH)?

We have four very small glands in our necks. They are about the size of small peas. These are what we call the parathyroid glands . These glands produce the parathyroid hormone, or PTH. The main function of this hormone is to control the level of calcium in our blood. It is a very amazing system. Think about it this way:

• When your blood calcium levels drop , these glands release the hormone PTH into your blood. This PTH goes to collect calcium from your bones and kidneys and brings your calcium levels back to normal.
• When your blood calcium levels rise , these glands stop releasing the PTH hormone. This controls your blood calcium levels.

So, measuring your PTH level is very helpful for doctors to find out exactly what is causing your blood calcium to be low or high.

Why would a doctor recommend this test?

The main thing is to determine whether the cause of your abnormal blood calcium level is a problem with the functioning of the parathyroid glands or another cause. If your PTH level is in line with your calcium level, it means that the cause of the abnormal calcium level is something else. Usually, if you have the following symptoms, your doctor may recommend this PTH test.

Are there any risks to this test?

There are actually very few risks involved. As with any blood test, you may feel some pain where the needle is inserted. You may also experience some bruising afterwards. Some people may feel a little dizzy after donating blood. But this is very normal. This can confirm or rule out a parathyroid disease. You and your doctor can then look for other causes of your abnormal calcium levels.

Do you need to prepare before the test?

Yes, your doctor may ask you to stop taking certain medications or vitamins (supplements) the day before or on the day of the test. But never stop taking any medication without first asking your doctor .

What happens during and after the test?

This is a very simple procedure. A small amount of blood is taken from a vein in your arm. The person taking the blood will first put a rubber band around the top of your arm and tighten it. When you squeeze your arm, the blood vessels will be clearly visible. Then, using a small needle, a small amount of blood will be drawn into a test tube. This does not require a large amount of blood. When the blood is drawn, the needle is removed and a small plaster is applied to the area. This blood sample is then sent to a lab to test levels of PTH, calcium, and possibly other hormones and minerals.

How to understand the results?

It can take a few days for test results to come back. However, sometimes results can be obtained more quickly, depending on the lab and the doctor's needs. The results are expressed in picograms per milliliter (pg/mL). The normal range for PTH can vary slightly from lab to lab. A healthy range for the `intact molecule` type of PTH is usually between 10 - 65 pg/mL .

Will I have to do more tests?

Yes, your doctor may recommend further tests depending on your PTH and calcium levels.

• For example, if your PTH levels are high but your calcium levels are low, it could mean that your parathyroid glands are working properly. Your doctor will then check your vitamin D, phosphorus, and magnesium levels to see if they are affecting your calcium levels.

• On the other hand, if your calcium level is high and your PTH level is higher than normal, you may have hyperparathyroidism. In that case, your doctor will do an X-ray or other imaging test to examine your parathyroid glands.

If the glands are swollen or have a tumor, surgery to remove the glands can be done. However, if your condition is not severe and you do not have symptoms such as kidney problems or weak bones, your doctor may want to check your calcium and PTH levels regularly. They may also prescribe a medication such as Cinacalcet (Sensipar). In such cases, surgery may not be necessary. Parathyroid hormone, PTH test, calcium, blood test, hypercalcemia, hypocalcemia, kidney disease