Parathyroid Hormone

Are you experiencing muscle cramps? Or does your bones easily deformed and fractured? All of these can happen if you have an abnormal parathyroid hormone concentration.

Parathyroid hormone or parathormone is a hormone that is primarily secreted by the parathyroid gland which is responsible for the regulation of the blood calcium levels in our body. Parathyroid hormone is much important than calcitonin ( hormone released by the thyroid gland cells, same action as to PTH ) in regulating blood calcium levels.

Primary action of Parathyroid Hormone;

• Binds to a membrane bound cell receptors and increases the calcium ions from the intestine thereby causing an increase in active Vit D formation.

• Increases bone tissue breakdown to release calcium ions into the circulatory system and decreases the rate at which the calcium ions are excreted in the urine.

• Acts on its target tissue to raise blood calcium ion level to a normal range.

Clinical Significance

Hyperparathyroidism

• Abnormally high concentration of the PTH secretion.
• Result from a tumor of the parathyroid gland
• Excess calcium ions can lead to kidney stone because calcium ions will be deposited in the soft tissues of the body.
• Elevated PTH concentration in the blood can increase bone breakdown thereby resulting in increase concentration of the blood calcium levels leading to have soft, deformed and easily fractured bones. It can also lead to fatigue and muscle weakness due to the less excitation of the nerves and muscles.

Hypoparathyroidism

• Abnormally low concentration of the PTH secretion.
• Result from an injury or surgical removal of the thyroid and parathyroid gland
• Low PTH concentration of blood can result to bone breakdown and reduced Vit D formation. As a result, blood calcium ion levels decrease tend the nerves and muscles to become excitable thereby producing spontaneous action potential that can result to muscle cramps or tetanus that can affect the respiratory muscles thereby stopping the breathing and can result to death.

Method of determination:

Radioimmunoassay represents the primary means of quantitating parathyroid hormone.

Reference:

Essentials of Anatomy and Physiology by Rod R. Seeley, Trent D. Stephens, Philip Tate.