25-hydroxyvitamin D

Definition

25-hydroxyvitamin D, also known as calcidiol, is the primary circulating form of vitamin D in the bloodstream and serves as a key indicator of vitamin D status in the body. This metabolite is produced in the liver from vitamin D obtained through sunlight exposure or dietary sources and is crucial for calcium homeostasis and bone health, linking it directly to nutritional assessment.

5 Must Know Facts For Your Next Test

1. 25-hydroxyvitamin D levels are measured through a blood test, and values below 20 ng/mL typically indicate a deficiency.
2. The half-life of 25-hydroxyvitamin D in the bloodstream is about two to three weeks, making it a reliable marker for assessing long-term vitamin D status.
3. Sources of vitamin D include sunlight exposure, fatty fish, fortified foods, and supplements, all of which contribute to the levels of 25-hydroxyvitamin D in the body.
4. Deficiency in 25-hydroxyvitamin D can lead to impaired calcium absorption, resulting in weakened bones and increased risk of fractures.
5. Optimal levels of 25-hydroxyvitamin D are generally considered to be between 30-50 ng/mL for maintaining good health.

Review Questions

• How does 25-hydroxyvitamin D reflect an individual's overall vitamin D status and why is this important?
  • 25-hydroxyvitamin D is crucial for assessing an individual's vitamin D status because it is the main form of vitamin D found in the bloodstream. Its levels indicate how well the body has absorbed vitamin D from sunlight or dietary sources. Monitoring this metabolite is essential since low levels can lead to various health issues, particularly related to bone strength and calcium metabolism.
• Discuss the relationship between 25-hydroxyvitamin D levels and bone health, including potential consequences of deficiency.
  • There is a significant relationship between 25-hydroxyvitamin D levels and bone health. Adequate levels are necessary for optimal calcium absorption from the gut, which is vital for maintaining bone density. A deficiency can lead to conditions such as rickets in children or osteomalacia in adults, where bones become soft and weak, increasing the risk of fractures and skeletal deformities.
• Evaluate the implications of measuring 25-hydroxyvitamin D levels in nutritional assessments and public health initiatives.
  • Measuring 25-hydroxyvitamin D levels has important implications for nutritional assessments and public health strategies. It provides insight into population-wide vitamin D status, guiding public health recommendations for supplementation or dietary changes. Understanding these levels can also help identify at-risk groups who may benefit from targeted interventions, thus improving overall health outcomes and preventing vitamin D deficiency-related diseases on a broader scale.

Related terms

Vitamin D:

A fat-soluble vitamin that is essential for maintaining bone health, immune function, and calcium balance in the body.

Calcitriol: The active form of vitamin D, produced from 25-hydroxyvitamin D in the kidneys, which helps regulate calcium and phosphate levels in the blood.

Hypovitaminosis D: A condition characterized by low levels of vitamin D in the body, which can lead to bone disorders such as rickets in children and osteomalacia in adults.