Parathyroid Hormone PTH Intact without Calcium
What is the Intact PTH without calcium test?
An intact PTH without calcium test is used to determine the blood levels of parathyroid hormone without calcium levels. PTH, or parathormone, is a hormone released by the parathyroid glands. Parathyroid glands are about four; small almond-shaped glands present one behind each of the upper and lower lobes of the thyroid gland. These are responsible for maintaining blood calcium, vitamin D, and phosphate levels with the help of parathormone. Our blood calcium levels influence the parathyroid glands to produce PTH.
The parathyroid hormone works by providing a powerful mechanism for controlling blood calcium and phosphate concentrations by regulating intestinal absorption, renal excretion, and exchange between the blood and bone of these ions.
Excess parathyroid hormone activity can also cause too much release of calcium from the bones, which results in hypercalcemia (abnormally high blood calcium levels), whereas hypofunction of the parathyroid gland results in hypocalcemia (abnormally low blood calcium levels).
What is this test used for?
An intact PTH and calcium test tells us the amount of parathyroid hormone released by the parathyroid gland, which with blood calcium can be used to identify conditions like;
- Hyperparathyroidism.
- Hypoparathyroidism.
- Abnormal blood calcium due to any other parathyroid glands disease.
If blood calcium levels are low, they stimulate the parathyroid glands to secrete more PTH. Conversely, high blood calcium levels cause the parathyroid glands to lower their production of PTH.
Why and when do you need an intact PTH without calcium test?
Your doctor can order an intact PTH without calcium test if you are suspected of a condition involving the parathyroid gland. Your doctor can also suggest this test if your previous blood calcium tests were not normal or you are having symptoms of hypercalcemia or hypocalcemia. The signs and symptoms of hypercalcemia include;
- Intense thirst.
- Bone pain.
- Weakness.
- Frequent urination.
- Loss of appetite.
- Constipation.
- Mental retardation.
- Kidney pain.
- Muscle twitching.
The signs and symptoms of hypocalcemia include the following:
- Dry skin.
- Seizures.
- Muscle cramps.
- Depression.
- Abnormal heart rate.
Checking blood calcium along with PTH can also be helpful to diagnose if the parathyroid gland is playing a role in the alteration of the blood calcium.
What kind of sample is required for an intact PTH without calcium test?
An intact PTH without calcium test requires a blood sample drawn out in a medical office or laboratory. For taking a blood sample, a lab technician will tie an elastic band to your arm to help find a vein. After which, a needle will be inserted into the vein, and the blood will come out and be stored in a tube. The sample will be sent to the laboratory and examined for parathyroid hormone.
Do you need to prepare for the test?
Usually, no preparations are necessary before drawing the blood out for this test. However, you should ask your doctor if you are supposed to avoid eating or drinking before the test. It is also recommended to let your doctor know about any medications you are taking routinely to prevent any changes in the test results. Some medications such as antacids and vitamin-D supplements may vary blood calcium levels.
Are there any risks to this test?
There are no serious risks involved with a blood test. You will feel a slight prick with some bleeding during the test, following some bruising and soreness. Rarely serious complications might occur, which are;
- Excess bleeding.
- Puncture in veins.
- Blood accumulation under the skin or hematoma.
- Fainting.
- Infection at the punctured skin.
What does the test result mean?
Normal PTH levels vary and depend upon the laboratory which has performed the test. Conditions resulting from abnormal levels of PTH are mentioned below;
Low PTH levels:
If your PTH levels are low, that means your parathyroid glands are not secreting sufficient PTH, due to which osteoclastic activity of bone resorption decreases and the calcium release from the bone stops, which causes a reduction in levels of calcium in the blood and other body fluids and tetany results. Tetany most commonly affects the laryngeal muscles causing their spasm, which obstructs respiration and can lead to death.
High PTH levels:
High PTH levels can be due to primary hyperparathyroidism, a condition in which the parathyroid glands abnormally secrete excess PTH. Hyperparathyroidism causes extreme osteoclastic activity and bone resorption increasing blood calcium abnormally high (hypercalcemia). This condition usually occurs in females because the parathyroid gland is stimulated by pregnancy or lactation. Severe cases of hyperparathyroidism result in bone diseases due to excess decalcification. Bone complications include fractured bones, broken bones, and cystic bone disease.
The Second hyperparathyroidism also associates high levels of PTH, which results as compensation for hypocalcemia. In this condition, the kidneys are unable to make sufficient vitamin D.
Related tests:
- Vitamin-D levels.
- Phosphorus levels.
- Creatinine test.
Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on June 04, 2023.
References
Magnesium modulates parathyroid hormone secretion and upregulates parathyroid receptor expression at moderately low calcium concentration | Nephrology Dialysis Transplantation | Oxford Academic
https://academic.oup.com/ndt/article/29/2/282/1912630#google_vignette
Low calcium:phosphorus ratio in habitual diets affects serum parathyroid hormone concentration and calcium metabolism in healthy women with adequate calcium intake | British Journal of Nutrition | Cambridge Core
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