Vitamin D refers to a family of compounds that play a pivotal role in the proper growth and formation of bones and teeth. This test is used to measure the level of Vitamin D in the blood. Two forms of Vitamin D can be measured in the blood, 25 hydroxyvitamin D and 1.25-dihydroxyvitamin D. The former is the primary form that is found in the blood and is a relatively inactive precursor to the active form of vitamin D: 1.25 dihydroxy vitamin D.
Since 25 hydroxyvitamin D has a long half-life and is present in higher concentrations in the blood, it is commonly measured to assess and monitor the status of vitamin D in the patient.
is sourced from endogenous and exogenous sources. Endogenous sources are produced in the skin in response to exposure to sunlight, and exogenous sources are ingested in food and supplements.
The role of Vitamin D is to help regulate the levels of calcium, phosphorus, and magnesium in the blood. Vitamin D is essential for the growth and health of bones. In the absence of vitamin D, bones tend to be malformed, soft, and unable to repair themselves normally. These circumstances lead to a disease known as rickets in children and osteomalacia in adults.
Vitamin D has also been shown to play a role in the differentiation and growth of tissues and aids in regulating the immune system. These functions may implicate Vitamin D in varying conditions/diseases like cancer and autoimmunity. Patients at higher risk of vitamin D deficiency include the elderly, the obese, people with poor sun exposure, people who have dark skin, and those who are on certain types of medication for a long.