What Does The Test Result Mean
Although there are differences among vitamin D methods, most laboratories utilize similar reference intervals. Because toxicity is rare, the focus has been on the lower limit and what cut-off for total 25-hydroxyvitamin D indicates deficiency.
- The Endocrine Society defines vitamin D deficiency as a 25-hydroxyvitamin D blood level below 20 ng/mL and vitamin D insufficiency as a level between 2129 ng/mL .
- The U.S. Institute of Medicine has concluded that a 25-hydroxyvitamin D level of 20 ng/mL or above is adequate for bone health, and that levels greater than 30 ng/mL do not offer significantly better effects. However, it is fair to say that the level of 25-hydroxyvitamin D associated with protection from the many other disorders recently associated with a lack of vitamin D is controversial.
25-hydroxyvitamin DA low blood level of 25-hydroxyvitamin D may mean that a person is not getting enough exposure to sunlight or enough dietary vitamin D to meet his or her bodys demand or that there is a problem with its absorption from the intestines. Occasionally, drugs used to treat seizures, particularly phenytoin , can interfere with the production of 25-hydroxyvitamin D in the liver.
There is some evidence that vitamin D deficiency may increase the risk of some cancers, immune diseases, and cardiovascular disease.
A high level of 25-hydroxyvitamin D usually reflects excess supplementation from vitamin pills or other nutritional supplements.
How Do They Test For Vitamin D Deficiency In San Marcos
A blood test for vitamin D deficiency can be performed to identify vitamin D deficiency. Vitamins D2 and D3 in the bloodstream convert to 25-hydroxy vitamin D, which can be measured with a vitamin D test to check whether you’re deficient. For a vitamin D blood test, a tiny needle is used to extract a little sample of blood from a vein in your arm. Your sample is then examined in a lab to check if you are vitamin D deficient.
When To Get Tested
When you have an abnormal calcium, phosphorus, and/or parathyroid hormone level when you have evidence of bone disease or bone weakness when you are at high risk of deficiency or a healthcare practitioner suspects that you might have a vitamin D deficiency prior to starting drug treatment for osteoporosis periodically to monitor treatment of vitamin D deficiency
What Are The Signs And Symptoms Of Vitamin D Deficiency
Severe lack of vitamin D causes rickets, which shows up in children as incorrect growth patterns, weakness in muscles, pain in bones and deformities in joints. This is very rare. However, children who are deficient in vitamin D can also have muscle weakness or sore and painful muscles.
Lack of vitamin D is not quite as obvious in adults. Signs and symptoms might include:
How Is It Used
A vitamin D test is used to:
- Determine if bone weakness, bone malformation, or abnormal metabolism of calcium is occurring as a result of a deficiency or excess of vitamin D
- Help diagnose or monitor problems with parathyroid gland functioning since PTH is essential for vitamin D activation
- Screen people who are at high risk of deficiency, as recommended by the National Osteoporosis Foundation, the Institute of Medicine, and the Endocrine Society
- Help monitor the health status of individuals with diseases that interfere with fat absorption, such as cystic fibrosis and Crohn disease, since vitamin D is a fat-soluble vitamin and is absorbed from the intestine like a fat
- Monitor people who have had gastric bypass surgery and may not be able to absorb enough vitamin D
- Help determine the effectiveness of treatment when vitamin D, calcium, phosphorus, and/or magnesium supplementation is prescribed
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Vitamin D Testing Not Recommended For Most People
- By , Executive Editor, Harvard Heart Letter
ARCHIVED CONTENT: As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date each article was posted or last reviewed. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Over the past decade, a barrage of reports linking low vitamin D levels to cancer, heart disease, diabetes, and a host of other ills led many doctors to routinely test vitamin D levels in their healthy patients. But there is no good reason to do that, according to a new recommendation from the U.S. Preventive Services Task Force published in this weeks Annals of Internal Medicine.
After reviewing the results of 25 vitamin D studies, the panel concluded that it isnt helpful for most people to know their vitamin D level. For one thing, experts dont agree on what low vitamin D means. Some laboratories define it as below 20 nanograms per milliliter , others set it at below 50 ng/mL. In addition, tests for vitamin D arent standardized or reliable.
Perhaps most important, even if you have a low vitamin D level theres scant evidence that taking a vitamin D supplement will do you any goodwith one exception. People low in vitamin D who take a supplement may be less likely to fall. That makes sense, given that vitamin D plays a key role in keeping bones and muscles strong.
Why You Need Vitamin D3
A deficiency of vitamin D can have serious consequences in the body. Vitamin D is vital for these reasons:
1. Bone Health
Doctors discovered vitamin D when they were studying rickets, a children’s bone disorder. Today rickets is rare, but vitamin D is still needed for bone health. It’s especially important for women past menopause, who are at risk of osteoporosis. Vitamin D is also used to treat a more serious bone condition called osteomalacia . Vitamin D allows the body to absorb calcium. Without vitamin D, the body uses only a small percentage of the calcium in food.
2. Anti-Cancer Properties
Higher levels of vitamin D in the blood are associated with lower levels of some cancers, including colorectal,prostate, and pancreatic. In animal studies, vitamin D was associated with fewer tumors and slower growth of tumors. Clinical trials in humans suggest that vitamin D may not prevent cancer but may slow its progress.
3. Brain Health
Low levels of vitamin D may be a risk factor for various forms of dementia, including Alzheimer’s disease. Animal studies and cell studies have shown a connection, but the results of clinical trials have been mixed. Further research is needed.
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Vitamin D Tests: When You Need Them And When You Dont
Many people dont have enough vitamin D in their bodies. Low vitamin D increases the risk of broken bones. It may also contribute to other health problems. Thats why health care providers often order a blood test to measure vitamin D.
But many people do not need the test. Heres why:
A test usually does not improve treatment.
Many people have low levels of vitamin D, but few have seriously low levels. Most of us dont need a vitamin D test. We just need to make simple changes so we get enough vitamin D. We need to get a little more sun and follow the other advice found below.
Even if you are at risk for other diseases, like diabetes and heart disease, a vitamin D test isnt usually helpful. The test results are unlikely to change the advice from your health care provider. It is much more important for you to make lifestyle changes firstto stop smoking, aim for a healthy weight and be physically active. And, like most other Canadians, you should try to get enough vitamin D from sun and foods. And talk to your health care provider about supplements.
Extra tests lead to extra treatments.
Getting tests that you dont need often leads to treatments you dont need, or treatments that can even be harmful. For example, if you take too much vitamin D, it can damage your kidneys and other organs.
When should you have a vitamin D test?
Talk to your health care provider about your risks. Here are some conditions where you might need a Vitamin D test:
How can you get enough vitamin D?
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Vitamin D And Calcium For Bone Health In Postmenopausal Women And Older Men
Post-menopausal women and older men have traditionally been recommended 800 IU/day of vitamin D due to their increased risk of osteoporosis and osteoporotic fractures. This recommendation has been questioned. A recent meta-analysis reported no effect on the risk of fractures or falls and bone mineral density with vitamin D supplementation in community-dwelling women age 65 years or older.18 The US Preventative Services Task Force concluded that the current evidence is inconclusive to assess the benefits and harms of supplementation with vitamin D alone or in combination with calcium for the primary prevention of factures in community-dwelling postmenopausal women and asymptomatic men.19However, considering the strengths and limitations of the analyses, Osteoporosis Canada maintains that individuals with osteoporosis or with risk factors for fractures receive adequate vitamin D, recommended at 800-2,000 IU/day.20,21
- For specific recommendations for patients at risk of osteoporosis, see the associated guideline at BCGuidelines.ca: Osteoporosis Diagnosis, Treatment and Fracture Prevention.
What Does Your Diet Have To Do With Getting Enough Vitamin D
Vitamin D doesnt occur naturally in many foods. Thats why certain foods have added vitamin D. In fact, newer food nutrition labels show the amount of vitamin D contained in a particular food item.
It may be difficult, especially for vegans or people who are lactose-intolerant, to get enough vitamin D from their diets, which is why some people may choose to take supplements. It is always important to eat a variety of healthy foods from all food groups. The vitamin content of various foods is shown in the following table.
Vitamin D content of various foods
|Cheese, Swiss, 1 ounce||6|
It is important to check product labels, as the amount of added vitamin D varies when it is artificially added to products such as orange juice, yogurt and margarine.
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How Vitamin D Became So Controversial
The controversies about the benefits of vitamin D reflect how science evolves, said Dr. Barry Kramer, director of the cancer prevention division at the National Cancer Institute.
Early research on the benefits of vitamin D was mostly observational large-scale, population-level studies and did not look at endpoints that are important for long-term health, like whether a high vitamin D intake reduces one’s risk for particular diseases or death.
Researchers found associations between higher levels of vitamin D intake and a range of health benefits. “But with the observational studies especially when you’re dealing with dietary supplements and diet taking supplements is also associated with many other confounding factors that predict the outcome: being wealthier, being health-conscious, having health insurance and access to the health care system, low smoking prevalence, increased physical exercise,” said Kramer.
In other words, the people who were taking these vitamins were doing many other things that might have caused them to have better health outcomes. Still, this early science encouraged people to hop on the vitamin D bandwagon.
There are also well-documented costs associated with overtesting and getting too much vitamin D: the cost to the health system for all those tests, and the potential harms from high vitamin D levels, such as kidney stones and high calcium which can cause nausea, vomiting, and loss of appetite.
Is Vitamin D A Necessary Component Of Calcium Supplements
Since absorption of calcium is dependent on vitamin D, many manufacturers of calcium supplements add vitamin D to assure optimal calcium uptake. If you have adequate amounts of vitamin D from other sources, the additional vitamin D is not necessary. The amount of vitamin D in these tablets is not likely to lead to excess vitamin D or be harmful either.
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Why Is Vitamin D So Important
Vitamin D is one of many vitamins our bodies need to stay healthy. This vitamin has many functions, including:
- Keeping bones strong: Having healthy bones protects you from various conditions, including rickets. Rickets is a disorder that causes children to have bones that are weak and soft. It is caused by a lack of vitamin D in the body. You need vitamin D so that calcium and phosphorus can be used to build bones. In adults, having soft bones is a condition called osteomalacia.
- Absorbing calcium: Vitamin D, along with calcium, helps build bones and keep bones strong and healthy. Weak bones can lead to osteoporosis, the loss of bone density, which can lead to fractures. Vitamin D, once either taken orally or from sunshine exposure is then converted to an active form of the vitamin. It is that active form that promotes optimal absorption of calcium from your diet.
- Working with parathyroid glands: The parathyroid glands work minute to minute to balance the calcium in the blood by communicating with the kidneys, gut and skeleton. When there is sufficient calcium in the diet and sufficient active Vitamin D, dietary calcium is absorbed and put to good use throughout the body. If calcium intake is insufficient, or vitamin D is low, the parathyroid glands will borrow calcium from the skeleton in order to keep the blood calcium in the normal range.
How Does Vitamin D Testing Work
In your bloodstream, Vitamin D2 and Vitamin D3 are changed into a form of Vitamin D called 25 hydroxyvitamin D, or 25D. myLAB Boxs Vitamin D blood test measures the level of 25D in your blood. Abnormal levels of Vitamin D can indicate bone disorders, nutrition problems, organ damage, or other medical conditions. By becoming aware of any potential deficiencies, you can take steps to increase your Vitamin D levels.
Connection Between Vitamin D and Cancer
Some studies have linked low levels of Vitamin D with certain forms of cancer. For instance, a study presented at the annual meeting of theAmerican Society for Radiation Oncology found that more than three-fourths of people with a variety of cancers had low levels of Vitamin D.
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Should I Take A Vitamin D Supplement
What then, is the best way to get this all-important vitamin, the sun or a supplement?
No matter how vitamin D is obtained, it ends up in the exact same form once it hits the liver . While I would personally suggest getting vitamin D from the sun if possible because of the other benefits of sun exposure, the most important thing is to just get vitamin D. If sun exposure is not possible or not feasible, supplementing orally is necessary.
When Is It Ordered
25-hydroxyvitamin DWhen calcium is low and/or a person has symptoms of vitamin D deficiency, such as bone malformation in children and bone weakness, softness, or fracture in adults , 25-hydroxyvitamin D usually is ordered to identify a possible deficiency in vitamin D.
The test may be requested when an individual is known to be at risk of vitamin D deficiency. Older adults, people who are institutionalized or homebound and/or have limited sun exposure, those who are obese, who have undergone gastric bypass surgery, and/or who have fat malabsorption are at an increased risk of a vitamin D deficiency. Also included in this group are people with darker skin and breastfed infants.
25-hydroxyvitamin D is often requested before an individual begins drug therapy for osteoporosis.
1,25-dihydroxyvitamin DThis testing may be ordered when kidney disease or abnormalities of the enzyme that converts 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D is suspected. Rarely, this test may be done when calcium is high or a person has a disease that might produce excess amounts of vitamin D, such as sarcoidosis or some forms of lymphoma .
When vitamin D, calcium, phosphorus, or magnesium supplementation is necessary, vitamin D levels are sometimes measured to monitor treatment effectiveness.
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How Does The Everlywell At
The Everlywell Vitamin D Test is an easy way to check your vitamin D level. Hereâs how it works:
Once you order the Vitamin D Test kit , weâll ship it directly to you.
Register your test online at www.everlywell.com/register using the unique kit ID thatâs included in your kit.
To take this blood test, use the card inside the kit to collect your blood sample. The kit includes a lancet for pricking your finger and simple instructions to guide you through the process.
Once youâve completed collection, ship your sample to a lab using the prepaid shipping label in the kit.
In just days, your test results will be available to you on our secure, online platform.
Vitamin D Home Test Complete Kit
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