The Vitamin D 25-hydroxy blood test is considered to be the most accurate method of determining how much of this vitamin is within the body. When it is in the kidneys, it is converted into an active vitamin that helps to control calcium and phosphate levels. It is only ordered when there is a suspicion that there is a vitamin deficiency or normal values must be verified before beginning a drug treatment.
This blood test can also be used to verify the health of individuals who struggle with fat absorption. This includes Crohn’s disease and Cystic Fibrosis as the vitamin is normally absorbed through the intestines because it is fat soluable. Once a deficiency has been identified, the Vitamin D 25-hydroxy blood test is also used on a continual basis to monitor treatment results.
A medical provider will order this blood test if there is the suspicion of an electrolyte imbalance or there is physical evidence of bone weakness or disease. Individuals who have had gastric bypass surgery to encourage weight loss may also have this test frequently ordered to monitor their health.
What Do My Test Results Mean?
High test results in the Vitamin D 25-hydroxy blood test are extremely rare and toxicity levels are even more rare. High results are typically because of supplements being taken. Because of this, most results are reported as either “normal” or “deficient.” An individual can be deficient in one or in both vitamins. Normal results for Vitamin D are anything above 30 ng/mL, while normal results for the 25-hydroxyvitamin are anything above 20 ng/mL.
Normal results typically mean no further testing is necessary. If there are physical symptoms being investigated, a normal result excludes these two vitamins from the cause.
If there is a deficiency present, then the most common reasons are because of a dietary issue or that someone isn’t getting enough sunlight exposure during the day. Certain drugs, such as Dilantin, have also been known to interfere with 25-hydroxy production. It can also be an indication that kidney disease has developed. Low levels of 25-hydroxy are one of the earliest changes associated with early kidney failure.
Although high Vitamin D levels can lead to calcification, the danger is that magnesium levels are too low. This creates a calcium that is resistant to the vitamin and can create calcification even though the blood test results came back as normal.
Here’s What You Need to Know
There are estimated daily intake values of Vitamin D and calcium that have been published since 2010 and are based on an individual’s age and their current life situation. The estimate average requirement begins at 500mg per day for calcium and 400mg per day of Vitamin D. The amount of Vitamin D does not change as people age, but the amount of calcium required tops out at 1,000mg per day for women who are above the age of 51.
Many people can get the Vitamin D that they need from fortified foods. This is especially critical in climates where there is limited sunlight exposure available. It may also be necessary in high sun environments where extensive use of sunscreen occurs. Milk and infant formulas are the two most commonly fortified foods that are available. This vitamin only naturally occurs in a few foods like cod liver oil, so drinking fruit juice, milk, and breakfast cereals is important, especially for children.
For kids, having a Vitamin D deficiency can lead to the development of juvenile rickets.
It is important to look at the ingredients of a calcium supplement before adding Vitamin D as an additional supplement. Many calcium supplements contain Vitamin D in them because it is necessary to have the vitamin present for the calcium to be processed properly.
Deficiencies in these vitamins may increase the risk of certain serious health issues developing in the future.
This includes certain cancers, immune diseases, and heart disease. For most people, only prescription level supplements of these vitamins can lead to toxicity. The issue is making sure that enough of them are being consumed every day in foods and supplements and that sunlight exposure happens.
Early testing can help to create an early intervention. The Vitamin D 25-Hydroxy blood test will measure vitamin levels and let your medical provider create a treatment plan that is based on your unique medical history. Use this guide to ask questions about what your test results mean so that you have the information you want about your health.