Parathyroid Hormone (PTH) and Calcium

What are PTH and Calcium?

Calcium is an essential mineral, needed for the development strong bones and teeth. When Calcium levels are within normal ranges, you have healthy blood vessels, muscles and nerves. Calcium is needed in our body for three primarily essential functions. First, it provides the necessary electrical energy for our nervous system. Second, it provides the essential electrical energy for our muscular system. Third, it offers strength to our skeletal system. Our bones are the storage system for this mineral. Our system continuously uses and deposits calcium in the bones. Think of it as a bank receiving many deposits and withdrawals. Calcium is the only element in our body that has its own regulatory system, which are the parathyroid glands.

PTH, otherwise known as parathyroid hormone or parathyrin, is a hormone produced by the parathyroid glands. Parathyroid glands consist of four small glands located in the neck behind the thyroid. These mini glands, have exactly same function, regulate and monitor calcium in our body. Being a very essential element in our body, calcium is carefully regulated in our system. The role of the parathyroid hormones is to watch out for our calcium levels so that our entire body can function properly. It is essential to keep in mind that parathyroid glands are not, in any way, linked to the thyroid glands: they are only adjacent to each other.

Parathyroid glands and calcium are interrelated. When the glands are not functioning properly, this usually means that just one of the glands is not working well, leading to an excess PTH hormone heading to our bones and causing the withdrawal of our calcium stores, from the bones to the blood. This usually translates into high blood calcium levels. Individuals whose parathyroid gland does not function properly, have been found to develop osteoporosis.

Why take the PTH and Calcium test?

Maintaining proper blood calcium levels is important to make sure that all our bodily functions are preserved. You need to test your PTH levels if:

• You suspect high levels of calcium that are accompanied by numerous symptoms such as fatigue, nausea, thirst and abdominal pain.
• You suspect that you have less than required amount of calcium in your blood that leads to abdominal pain, muscle cramps and tingling fingers.
• You already tested your calcium levels, and the result came out abnormal.

The PTH and calcium test is normally ordered to check the functioning of the parathyroid glands and to distinguish between disorders: whether they are caused you to parathyroid related problems or non-parathyroid related disorders. Also, this double test is used to follow up on certain treatment done to the parathyroid; and to make sure its effective. PTH/Ca tests are also a great way to pinpoint the reason why you have low phosphorus levels, severe osteoporosis that is not being cured; and, to monitor some chronic conditions like kidney illnesses.

Many health professionals advise patients to take the PTH test along the calcium test, especially if they were treated for a condition affecting calcium levels, like having the parathyroid gland removed or for an end-stage renal disease.

What can cause the levels of PTH to rise?

Many drugs can increase your PTH levels, such as phosphates, anticonvulsants, steroids, isoniazid, lithium and rifampin. Also, but to a lesser extent, PTH levels may be higher than normal when someone is working out and afterwards. Such a rise depends on the duration and intensity of the workout. Race, also, has an effect on your PTH levels. A study showed Mexican and African-Americans tend to have higher levels of PTH than other populations. Obesity can also affect your PTH levels. Higher total body fat typically results in higher PTH levels.

What your PTH and Calcium test results mean?

Normal values of PTH range between 10 and 65 pg/ml. Normal calcium levels range between 8.8 and 10.4 mg/dL in adults. In children, calcium levels should be between 6.7 and 10.7 mg/dL.

There are many ways to test for PTH. This causes slight changes in the reference normal ranges. PTH and calcium test results are interlinked in such a way that, under normal circumstances, when the calcium levels are lower than normal, the PTH levels are higher than normal; and vice versa.

When the PTH levels are lower than normal, it usually indicates some condition that is causing your low calcium levels. These include hypoparathyroidism, autoimmune disorders, cancer, overtaking calcium supplements, or having low levels of magnesium in your blood. Some lower than recommended levels can indicate vitamin D intoxication, sarcoidosis that causes inflammation of the tissue, or radiation exposure.

Higher than normal levels of PTH indicate hyperparathyroidism, which is a usually caused by a benign parathyroid tumor. Other associated conditions include chronic kidney disease, pseudohypoparathyroidism, swelling of the parathyroid, or pregnancy and breastfeeding. High PTH levels can indicate high levels of calcium lost in urine. Finally, elevated levels can be caused by following a diet that is low in calcium; or having problems in the proper absorption of this mineral.

Following is a simplified guide that brings together results of calcium and PTH and possible interpretations:

1. If Calcium is normal and PTH is normal; then, your Calcium regulation system is functioning properly.
2. If calcium levels are low and PTH are high; then, the PTH is working well but you need further tests to detect the cause of your low calcium levels.
3. If calcium levels are low and the PTH levels are normal or low; then, PTH is not working well. This could be due to hypoparathyroidism or secondary hypocalcemia.
4. If Calcium levels are high and PTH levels are high; then, the parathyroid gland is making a lot of PTH . You may want to check for parathyroidism.
5. If Calcium levels are high and PTH levels are low; then, PTH is responding the right way but you need to conduct further tests to find the cause for elevated calcium levels.
6. If Calcium levels are normal and PTH levels are high; then hyperthyroidism may be indicated.

Where can I get a PTH and Calcium test near me?

Please use our Lab Locator to find find a convenient testing location.

Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: May 01, 2020