Vitamin D is an unusual vitamin because your body will manufacture adequate amounts of it if you spend enough time in the sun. However, the Dietary Reference Intakes from the USDA indicate that many people do not have enough vitamin D in their blood. If your doctor orders blood work to test your levels of vitamin D, understanding what the test results mean can help you understand whether you need vitamin D supplementation.
Importance
Your body uses vitamin D as a vehicle to help absorb the calcium you take in from food. Proper levels of calcium promote strong, dense bones. If your vitamin D levels are low, you are at risk for fractures and osteoporosis. Additionally, a 2011 study run by researchers from Emory University and Georgia Tech, which was presented at the 2011 meeting of the American College of Cardiology, indicated that people who had inadequate levels of vitamin D in their blood had stiff arteries and blood vessels that did not adequately relax. These conditions contributed to both increased blood pressure and a greater risk of developing cardiovascular disease. Once the participants received vitamin D supplementation, their blood pressure dropped and they experienced an improvement in their vascular health.
Food Sources
In addition to sunlight, some foods give you small amounts of vitamin D. Oily, cold water fish provide some vitamin D, as do vitamin D fortified foods such as orange juice, cereals, milk, yogurt and some grains. Eggs are also a minor source of vitamin D. Relying solely on food sources and no sun exposure for your vitamin D requirements may leave you deficient in vitamin D.
The Test
Your doctor may order a vitamin D test alone, or include the test with other blood tests. Your blood sample is tested using a test called 25-hydroxyvitamin D. Your doctor may also order the 1,25-dihydoxyvitamin D test. You should not eat for four hours prior to testing.
Intrepreting Results
A normal range of vitamin D in your blood from the 25-hydroxyvitamin D test is between 30 and 74 ng/mL, or nanograms per milliliter. If you have a lower amount of vitamin D in your blood, you may not be getting enough vitamin D in your diet, or you may lack enough sun exposure on your skin. Other possibilities include a kidney or liver disease; a problem with your body's ability to absorb vitamin D; or your use of medications that lower your level of vitamin D.
Doctor Recommendations
If your vitamin D blood test is low, he may recommend either an over-the-counter supplement or issue a prescription for higher doses of vitamin D. After taking the supplements for a prescribed period of time, your doctor will often repeat the blood test, adjusting your supplementation levels, if necessary.
Member Comments