Parathyroid hormone

and bone diseases

By: Hosam abd alkadum

Out lines: CalciumCalcium absorptionDisorders of Parathyroid Hormone

calcium:

One of the most important elements found in the body.

Structural component in bone and teeth. . 99% stored in the bone The average content of calcium in adults is 1 kg

Calcium absorption: refers to the transport of the calcium that received from food, from intestine into the blood.

Substances that increased calcium in

blood:

1. active form of Vitamin D.

2. Parathyroid hormone.

1. Active form of vitamin D Found two types from vitamin D:

vitamin D2 (ergocalciferol) vitamin D3 ( cholecalciferol)

Found two sources for vitamin D in human body: From Diet. From Dermal synthesis of vitamin D from cholesterol is

dependent on sun light (specifically UVB radiation).

Vitamin D from the diet or dermal synthesis form's sun light is biologically inactive

activation requires enzymatic conversion (hydroxylation) in the liver and kidney and activation by parathyroid hormone.

The active form of vitamin D absorption calcium from intestine.

Activation

Of Vitamin

D

2. Parathyroid hormone

Parathyroid hormone (PTH) is a hormone secreted by the parathyroid glands.

increase of Calcium concentration in plasma by:

1.Activation of vitamin Dз synthesis and increase of absorption in the intestine

Effect PTH on Activation of vitamin D

2. Increase of calcium reabsorption in kidneys

3. Releasing of Са by bones (osteoclasts)

Disorders of Parathyroid Hormone

Hyperparathyroidism

Hypo parathyroidism

metabolic disorder with excessive secretion of Parathyroid hormone (PTH).

can be characterized into primary, secondary, and tertiary.

Resulting in high levels of calcium in the blood (hypercalcemia), which can cause a variety of health problems.

causing bone furcating and bone pain.

Hyperparathyroidism

deficiency or absence of PTH secretion.

metabolic disorder characterized by low serum calcium.

Causes decrease in effective vitamin D in body.

Hypo parathyroidism