Parathyroid hormone

Why this test?

To assess the function of the parathyroid glands.

To find out the causes of hypo- or hypercalcemia, disorders of calcium metabolism.

For differential diagnosis of primary, secondary and tertiary hyperparathyroidism.

For diagnosing hypoparathyroidism.

To monitor patients with chronic calcium metabolism disorders.

To evaluate the effectiveness of treatment of parathyroid gland pathology and their surgical removal in neoplasms.

In what cases is it prescribed?

When the level of calcium in the blood changes (hyper- or hypocalcemia).

With symptoms of hypercalcemia (fatigue, nausea, abdominal pain, thirst) or hypocalcemia (abdominal pain, muscle cramps, tingling in the fingers).

When the size and structure of the parathyroid glands change according to instrumental methods (for example, CT).

In the treatment of disorders of calcium metabolism.

With neoplasms of the parathyroid glands, as well as immediately after their surgical removal.

With osteoporosis and changes in the structure of bone tissue.

With chronic kidney diseases and low GFR.

Test information

Parathyroid hormone (PTH) is produced by the parathyroid glands, which are located in pairs on the back surface of each lobe of the thyroid gland. Intact PTH (intact hormone molecule) consists of 84 amino acids, has a short half-life (about four minutes) and is the main biologically active form of the hormone. In its N- and C-terminal fragments, the period of existence is longer, their activity and metabolism are studied.

PTH plays an important role in the regulation of phosphorus-calcium metabolism and ensures the maintenance of a stable concentration of calcium and phosphorus in the extracellular fluid. The level of PTH is closely related to the amount of calcium, vitamin D, phosphorus, and magnesium in the body, its secretion is regulated according to the principle of feedback. With a decrease in the concentration of calcium in the blood (hypocalcemia), the secretion of PTH by the parathyroid glands increases, and with an increase (hypercalcemia), on the contrary, it decreases. These mechanisms are aimed at maintaining a stable level of calcium in the blood. An increase in PTH contributes to the activation of osteoclasts, resorption of bone tissue and the release of calcium from the bones, enhances the absorption of calcium from the intestines, delays the release of calcium by the kidneys and suppresses the reverse reabsorption of phosphorus. The antagonist of PTH is the hormone calcitonin, which is secreted by C cells of the thyroid gland. Normally, when the normal concentration of calcium in the blood is reached, the production of PTH decreases.