Parathyroid Hormone (PTH), Intact

What is PTH Intact?

PTH Intact is a peptide hormone made of 84 amino acids. This is why it is sometimes referred to as PTH (1-84). Our parathyroid gland secretes different types of PTH. Some are fragmented (missing 6 or more amino acids); and, some are intact.

Intact PTH are secreted less often than fragmented ones. Their role is to regulate calcium levels in our serum to an ideal value. PTH is more of a tool than a hormone. It gets secreted when serum calcium levels decrease; and, aims at boosting the absorption of calcium and lowering the absorption of phosphorus in our kidneys. When PTH intact is produced and released in our bloodstream, it will have a short period of time to do its job. Within 5 minutes after being released, its levels drop down by half due to its intensive role in our liver and kidneys.

Why take the PTH Intact test?

Being the most frequently ordered parathyroid hormone test, PTH Intact helps diagnose the root cause of an abnormal increase or decrease in calcium levels. It helps identify if these are caused by a parathyroid malfunction; or, other organs and lifestyle factors. Also, PTH Intact is a great tool to monitor how effective a parathyroid treatment is progressing.

Individuals with chronic kidney disease or those who are undergoing dialysis use PTH Intact levels to monitor their progress and kidney health status. Also, it is an important tool to monitor other illnesses and used as a post-operation indicator.

What can cause the levels of PTH Intact to rise?

The major cause of a rise in PTH Intact levels is kidney damage. An individual with impaired kidney function will not be able to balance the body’s electrolyte levels, especially phosphorus and calcium. Some drugs can cause an increase in Intact PTH levels, such as phosphates, steroids and anticonvulsants. Also, some heredity factors may play a role in a rise in PTH levels, such as familial hyperparathyroidism and MEN-I syndromes.

What your PTH Intact test results mean?

Normal values of Intact PTH need to be between 15 and 65 pg per ml. Low levels of PTH could be due to high calcium levels or abnormal production of PTH, or to an abnormal production of PTH caused by a gland malfunction. High levels of PTH Intact can be caused by a benign parathyroid tumor.

PTH Intact test results vary and should be interpreted with calcium levels for a better diagnosis. If the values of Intact PTH are between 15 and 65 pg/ml and calcium levels are between 8.6 and 10.2 mg/dL; then you are within the normal ranges of both.

When PTH levels go above 65 pg/mL; then, you have to take a look at your calcium levels to interpret results. If calcium levels are above 10.2 mg/dL; then you may have primary hyperparathyroidism. If calcium levels are below 10.2 mg/dL; then, you may have secondary hyperparathyroidism.

If Intact PTH levels are below 65 pg/mL and your calcium levels are above 10.2 mg/dL; then, you may have nonparathyroid hypercalcemia.

If PTH Intact levels are below 15 pg/mL and Calcium levels are below 8.6 mg/dL; then, you might have hypoparathyroidism.

Finally, if Intact PTH is between 15 and 65 pg/mL and your calcium levels are below 8.6 mg/dL; then, it probably is due to a non-parathyroid hypocalcemia.

In cases when the serum blood calcium levels alter at a slow rate, it is possible to have abnormal PTH levels without showing any symptom.

Where can I get a PTH Intact test near me?

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

Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: Oct 24, 2019