Calcitriol

Definition

Calcitriol is the active form of Vitamin D3, crucial for calcium homeostasis and bone metabolism. It facilitates the absorption of calcium in the intestines and its reabsorption in the kidneys.

5 Must Know Facts For Your Next Test

1. Calcitriol is synthesized in the kidneys from its precursor, calcidiol.
2. It increases serum calcium levels by enhancing intestinal absorption of calcium.
3. Calcitriol is used clinically to treat conditions like hypocalcemia and secondary hyperparathyroidism.
4. It plays a key role in regulating parathyroid hormone (PTH) levels.
5. Excessive use of calcitriol can lead to hypercalcemia, which presents with symptoms like nausea, vomiting, and weakness.

Review Questions

• What are the primary physiological roles of calcitriol?
• How does calcitriol affect parathyroid hormone (PTH) levels?
• What are some clinical indications for prescribing calcitriol?

Related terms

Calcidiol: The inactive precursor of calcitriol, also known as 25-hydroxyvitamin D.

Parathyroid Hormone (PTH): A hormone secreted by the parathyroid glands that regulates serum calcium levels.

Hypercalcemia: A condition characterized by abnormally high levels of calcium in the blood.