What Is A Vitamin D Test?
Vitamin D is a nutrient that is essential for healthy bones and teeth. In your bloodstream, vitamin D2 and vitamin D3 are changed into a form of vitamin D called 25 hydroxyvitamin D, also known as 25(OH)D. A vitamin D blood test measures the level of 25(OH)D in your blood. Other names: 25-hydroxyvitamin D, 25(OH.
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Portant for strong and healthy bones, and may help prevent a number of diseases. Vitamin D deficiency is common in Australians so your doctor might ask for a test if you are at risk.
What Is Being Tested?
Your skin makes vitamin D when it is exposed to sunlight.
The liver changes the vitamin D from the skin or food into a storage form called 25-hydroxy-vitamin D. It is this form that is usually measured in the vitamin D test.
Why Would I Need This Test?
Your doctor might ask you to have this test if you are at risk of being vitamin D deficient. Understanding your results
You will need to discuss with your doctor what the results mean for you. Generally, a low level of 25-hydroxy-vitamin D may mean you are not getting enough vitamin D from sunlight or from food.
It could also indicate problems with vitamin D absorption from your intestines, or that your liver is not making enough of this type of vitamin D.
A high level of vitamin D usually comes from taking too much in, either from pills or in food. Abnormal levels of a type of vitamin D produced in the kidney (1,25-dihydroxy-vitamin D) can be a sign of a range of other conditions. More information
About Vitamin D testing
Visit Lab Tests Online AU website for more information about Vitamin D testing.
Ask A Laboratory Scientist
Vitamin D comes from two sources: endogenous, which is produced in the skin on exposure to sunlight, and exogenous, which is ingested in foods and supplements. Vitamin D 3 is the form produced in the body and is also used in some supplements. Vitamin D 2 and D 3 are equally effective when they are converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.
Some tests do not distinguish D 2 and D 3 forms of the vitamin and report only the total result.
Newer methods, however, may report levels of both D 2 and D 3 and then add them together for a total level. The main role of vitamin D is to help regulate blood levels of calcium, phosphorus, and (to a lesser extent) magnesium. Vitamin D has also been shown to influence the growth and differentiation of many other tissues and to help regulate the immune system.
These other functions have implicated vitamin D in other disorders, such as autoimmunity and cancer. Adequate sun exposure is typically estimated to be two periods per week of 5-20 minutes. People who do not have adequate sun exposure may obtain the vitamin D that they need from food sources or supplement.