The PTH exam is requested with the objective of evaluating the functioning of the parathyroid glands, which are small glands located in the thyroid that have the function of producing the parathyroid hormone (PTH). PTH is produced in order to avoid hypocalcemia, ie low blood calcium concentrations, which can lead to seizures and heart failure in more severe cases and when there is no treatment. Learn more about what hypocalcemia is and what it can cause.
To do this test is not necessary fasting and is done with a small sample of blood. PTH dosage is primarily required to diagnose hypo or hyperparathyroidism, but is also required in the follow-up of patients with chronic renal failure, and is usually required along with the dosage of calcium in the blood. In people with no change in parathyroid hormone production normal blood levels should be between 12 and 65 pg / mL and may vary according to the laboratory.
Although it is not necessary to prepare before the examination, it is important to inform the doctor about the use of any medication, mainly sedatives such as Propofol, for example, as they may decrease PTH concentration, thus interfering with the interpretation of the result by the doctor. In addition, it is indicated that the collection should be done in a reliable laboratory or hospital with trained professionals, since hemolysis, which is often caused by errors in collection, may interfere with the test result.
How is the exam done?
The test does not need any preparation, however it is recommended that the collection be done in the morning, since its concentration can vary throughout the day. The collected blood is sent to the laboratory, where it is processed and placed on a device where the tests are performed. The result is usually released approximately 24 hours after collection.
Parathyroid hormone is produced in response to low blood calcium concentrations. It acts at the level of the bones, kidneys and intestine with the aim of increasing the availability of calcium in the blood and avoiding hypocalcemia. In addition, PTH is responsible for increasing the absorption of vitamin D by the intestine.
PTH activity is regulated by another hormone, calcitonin, which begins to be produced when calcium levels are very high, thus decreasing the production of PTH and stimulating the excretion of calcium in the urine, for example. Understand how the calcitonin test is done and what the test is for.
What can the result mean?
The result of the examination is interpreted by the physician together with the calcium dosage, since the production of parathyroid hormone depends on the concentration of calcium in the blood.
- High parathyroid hormone: Usually indicative of hyperparathyroidism, especially if the blood calcium level is elevated. In addition to hyperparathyroidism, PTH may be elevated in the case of chronic renal failure, vitamin D deficiency and hypercalciuria. Understand what hyperparathyroidism is and how to treat it.
- Low Parathyroid: It is indicative of hypoparathyroidism, especially if blood calcium levels are low. Low or undetectable PTH may also be indicative of autoimmune disease, incorrect development of glands or after surgical procedures. See what hypoparathyroidism is and how to identify it.
The PTH exam is requested by the physician when there is suspicion of hypo or hyperparathyroidism, before and after performing surgical procedures involving the thyroid or when there are symptoms of hypo or hypercalcemia, such as fatigue and abdominal pain, for example. Find out what are the main causes of excess calcium in the blood and how to treat it.
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