Sunday, February 25, 2024

Vitamin D 25 Hydroxy Blood Test

What Do The Results Of This Lab Test Mean

Vitamin D Levels and Risk of Mortality

The results of 25 hydroxy vitamin D test will usually include the following details:

  • Value of 25 hydroxy vitamin D3: The amount of vitamin D your body made on its own, absorbed through an animal source or from a cholecalciferol supplement
  • Value of 25 hydroxy vitamin D2: The amount of vitamin D absorbed from fortified foods or from an ergocalciferol supplement

Apart from these values, the total amount of this test is also an important part of the test result. The test result is measured in the unit of nanograms per milliliter and can vary among labs. Note that the normal level of vitamin D is recommended between 20-40 ng/mL or 30-50 ng/mL . Apart from normal, the following can be the categorization of the results of the test for vitamin D 25 hydroxy low and high.

If your vitamin D level is higher than the recommend range, it may be because of hypervitaminosis D, a condition where a high amount of vitamin D accumulates in your body. This can result from your body having too much calcium, also known as hypercalcemia.

Vitamin D 25 hydroxy low levels are usually caused by the following factors:

  • Liver or kidney disease

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Assay Variations Impact On Care And The Vitamin D Standardization Program

Although serum 25OHD is the best index of nutritional vitamin D status, its measurement to define desirable vitamin D levels is limited by large variations incurred by the various methodologies used to date. Such variations by far exceed the differences in desirable 25OHD levels defined by IOM and ES.

Vitamin D Testing In Children

Vitamin D deficiency and insufficiency can be a problem in infants and children. Vitamin D deficiency can cause a serious disease called rickets that affects bone development. Rickets may result in skeletal deformities, impaired growth, short stature, and dental problems.

Vitamin D deficiency in childhood is more common in countries where a large portion of the population is malnourished. However, certain risk factors that increase the chances of vitamin D deficiency can occur in infants and children in any country and include:

  • Exclusive breastfeeding since breast milk has low vitamin D content
  • Lack of sunlight exposure, darker skin pigmentation, and sunscreen use
  • Diets that limit intake of vitamin D-fortified foods

Health care providers may order vitamin D testing for infants and children with symptoms of vitamin D deficiency, such as skeletal changes. Some health providers will also screen young patients without symptoms, such as exclusively breastfed infants, children whose skin is darkly pigmented who live in areas with low sun exposure, and children whose diets are low in vitamin D.

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What Are The Possible Complications Of Vitamin D Deficiency

The most serious complications of vitamin D deficiency include:

  • Low blood calcium levels .
  • Low blood phosphate levels .

All of these conditions are treatable. While rickets is a treatable and often curable disease, treating it as soon as possible is important. When not treated, milder cases of rickets can result in long-term bone damage that can keep bones from growing properly. Severe cases that arent treated can lead to seizures, heart damage and death.

The good news is that thanks to vitamin D-fortified infant formula and fortified cows milk, rickets is very uncommon in the United States.

How Is Vitamin D Deficiency Diagnosed

Vitamin D Deficiency Testing

Healthcare providers dont usually order routine checks of vitamin D levels, but they might need to check your levels if you have certain medical conditions or risk factors for vitamin D deficiency and/or have symptoms of it.

Your provider can order a blood test to measure your levels of vitamin D. There are two types of tests that they might order, but the most common is the 25-hydroxyvitamin D, known as 25D for short.

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What Are The Risk Factors Associated With 25 Hydroxy Vitamin D Test

Usually, the risk involved in such a lab test is low. But it may be difficult to draw blood from some people as the size of veins and arteries among individuals can vary, and locating the right vein to draw blood may become difficult. It may require multiple punctures to locate a vein in such cases. Some other risks associated with this lab test are:

  • Light headedness or faintness

What Does The Test Measure

Vitamin D is necessary for maintaining health. It helps your body absorb minerals like calcium, magnesium, and phosphorus from your diet. Vitamin D also helps maintain proper levels of calcium, phosphate, and parathyroid hormone in your blood.

Vitamin D plays an important role in helping the body absorb calcium, which makes it crucial to maintaining bone health. Inadequate levels of vitamin D can lead to abnormal bone development, bone weakness, and pain.

Unlike other vitamins, Vitamin D can be created in the human body. When your skin is exposed to direct sunlight, ultraviolet radiation converts a chemical in your skin into an active form of vitamin D. Vitamin D can also be obtained through the diet, including from fortified or vitamin-enriched foods and vitamin supplements.

There are two major forms of Vitamin D:

  • Vitamin D2 : Vitamin D2 is created in plants, such as yeast or mushrooms. It is also available as a supplement and in fortified foods.
  • Vitamin D3 : Vitamin D3 is generated in the skin when it is exposed to sunlight. It is also found in some animal-based foods and may be consumed in certain fortified foods or dietary supplements.

Both vitamin D2 and D3 need to go through chemical changes before being able to be used by the body. These changes occur in the liver and the kidneys and convert vitamin D into measurable substances called 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D:

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Why Normal Levels Can Differ Across Different Labs

Each laboratory must establish its own normal ranges for vitamin D in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels, according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

Vitamin D levels depend on the exposure to the sunlight. They show seasonal variation with the highest concentrations in summer or fall and the lowest concentrations in winter or spring. In addition, the production of vitamin D has been reported to decrease with age.

The values shown above refer to the 25-hydroxy vitamin D test which is the main circulating form of vitamin D in the blood. However, there is also a test to measure the 1,25-dihydroxyvitamin D in the blood and the normal ranges for it are 15 to 60 pg/mL .

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Why Do I Need To Undergo A Vitamin D Test

Vitamin D and Renal Disease – Mayo Clinic

The test is done to assess the vitamin D levels in the body so that it can be determined whether you need supplements or more exposure to the sun. Many doctors do not recommend testing in healthy individuals unless there are specific symptoms present. The test is done specifically for some individuals who have the following issues. Individuals with a body mass index of 30 or greater and suffering from obesity can have deficiencies. Intake of certain medicines like phenytoin, phenobarbital, and rifampin. Those diagnosed with osteoporosis, bone weakness or bone softness. Individuals with limited sun exposure. Anyone with diseases like ulcerative colitis, Crohns disease or celiac disease prevents the normal absorption of vitamins in the body. Previous gastric bypass surgery or weight-loss surgery. Inadequate vitamin D absorption due to advanced age or conditions in which fat is not absorbed well in the body. People who have dark skin or wear total skin covering are also at risk of a deficiency.

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Study Participants And Design

Adult TB cases were recruited from the Medical Research Council TB clinic in Fajara, The Gambia. The diagnosis of active TB was established on the basis of smear positivity for acid-fast bacilli of Mycobacterium tuberculosis . All mycobacterial cultures were identified and confirmed using standard procedures. Household contacts of confirmed index cases were visited to assess their TB infection status and were followed for 2 years from recruitment. Tuberculin skin test was used as a measure of mycobacterial infection and was performed using 2 tuberculin units of purified peptide derivative RT23 injected intra dermally into the volar aspect of the forearm and read at 4872 h. TST was performed prior to any blood sampling of study participants. A reading of 10 mm was considered positive, and indicative of mycobacterial infection. The diagnosis of latent TB infection was established on the basis of absence of TB symptoms, absence of radiologic abnormalities of active TB and positivity for TST.

How To Prevent And Treat Vitamin D Deficiency

Many patients and physicians think that adequate vitamin D intake can be obtained via diet alone. This assumption is erroneous. With the exception of fatty fish, the vitamin D content of most foods, including fortified dairy products, is relatively low to nonexistent. Even some dairy products in the United States are not fortified, making it important to read food labels to ensure the vitamin D content of foods.

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Cme Questions About Vitamin D Deficiency In Adults

  • Which one of the following patients is at greatest risk for vitamin D deficiency?
  • A formula-fed infant
  • A teenaged girl eating an unrestricted diet and taking a multivitamin
  • A 30-year-old male nursing home resident treated with phenytoin for epilepsy
  • A 70-year-old woman with osteopenia taking a calcium carbonate with vitamin D supplement
  • A 43-year-old male farmer
  • Which one of the following biochemical tests provides the best initial assessment of a person’s vitamin D status?
  • Serum parathyroid hormone
  • What Are The Signs And Symptoms Of Vitamin D Deficiency


    Severe lack of vitamin D in children causes rickets. Symptoms of rickets include:

    • Incorrect growth patterns due to bowed or bent bones.
    • Muscle weakness.
    • Deformities in joints.

    This is very rare. Children with a mild vitamin deficiency may just have weak, sore and/or painful muscles.

    Lack of vitamin D isnt quite as obvious in adults. Signs and symptoms might include:

    However, you may have no signs or symptoms of vitamin D deficiency.

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    Assay Standardization And The Vitamin D Standardization Program

    Challenges in all of the above assay methods methods are clear, and a high level of technical expertise is required for performing manual test and designing any vitamin D method. External proficiency testing schemes , or external quality assessment schemes , such as DEQAS, and the vitamin D quality assessment service offered by the College of American Pathologists , are primarily based on the methodology being used in the respective laboratories, and results obtained vary widely. Examination of the quarterly reports issued by DEQAS that are based on data received from around 1000 laboratories, measuring four unknown samples, reveal wide variations in the mean serum 25OHD level derived by each specific methodology for the same sample of 8 to 16âng/mL . The histogram also reveals a consistent trend for the interassay differences between the mean for methodologies reported, varying between 2.5 and 16âng/mL. The closest to target value were those values obtained by LC-MS/MS, followed by HPLC . The above-reported 25OHD levels derived with each methodology are based on means values obtained from a few dozen to several hundred laboratories, and underestimate variations on individual patient measurements. At present, there exist no practical regulated and reference procedures for clinical measurement of serum 25OHD level. The choice of a particular method by a laboratory more often depends on available expertise, economics, and profitability.

    What About Vitamin D Toxicity

    Vitamin D toxicity should not be diagnosed solely on the basis of an elevated 25D level instead, it should be recognized as a clinical syndrome of both hypervitaminosis D and hypercalcemia, in which hyperphosphatemia and hypercalciuria also commonly occur. Patients with vitamin D toxicity could present with clinical symptoms and signs of hypercalcemia and hypercalciuria . Hypervitaminosis D in the absence of hypercalcemia may prompt further investigation to evaluate the etiology of increased vitamin D levels however, unlike hypercalcemia, it is not a medical emergency. Although excess vitamin D supplementation can lead to hypercalcemia, vitamin D toxicity is extremely rare and generally occurs only after ingestion of large doses of vitamin D for prolonged periods in patients with normal gut absorption or in patients who may be concurrently ingesting generous if not excessive amounts of calcium. A 25D level of 80 ng/mL is the lowest reported level associated with toxicity in patients without primary HPT with normal renal function. Most patients with vitamin D toxicity have levels greater than 150 ng/mL.28 Binkley et al21 have recently reported that vitamin D supplementation with 1600 IU/d or 50,000 IU monthly was not associated with any laboratory parameters of toxicity and even failed to increase total 25D levels above 30 ng/mL in 19% of participants.

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    How Much Does The Test Cost

    The cost of vitamin D blood testing depends on where you have the test taken, whether other tests are performed at the same time, and whether you have health care coverage.

    The costs of testing may include an office visit, a blood draw fee, and charges from the laboratory analyzing your blood sample. These costs are usually covered by insurance when the test is ordered by your health care provider. However, you may wish to check with your health insurance company to learn whether you are responsible for a deductible or copay.

    Can I Take The Test At Home

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    Several at-home test kits are commercially available that allow you to provide a blood sample for vitamin D testing. Some kits test only your vitamin D levels, and others test vitamin D in combination with additional measurements, such as other vitamins and minerals or C-reactive protein.

    Vitamin D home collection kits may be purchased online and include the materials you need to take a finger prick sample of blood that is returned by mail to the testing company to analyze. Your at-home vitamin D test results are usually reported to you via a secure online platform.

    At-home testing can be convenient and enable you to participate in your health care, but at-home tests cannot replace working with a health care professional. If you have symptoms of an abnormal level of vitamin D, be sure to share your concerns with your health care provider. If an at-home test detects a vitamin D deficiency, insufficiency, or toxicity, your doctor will likely recommend retesting your vitamin D level to confirm the result.

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    Beaker Location Container And Temperature


    Who Is Most At Risk For Vitamin D Deficiency

    Aside from medical conditions that can lead to vitamin D deficiency, biological and environmental factors that put someone at an increased risk of vitamin D deficiency include:

    • Age: Your skin’s ability to make vitamin D decreases with age, so people over the age of 65 years are especially at risk for vitamin D deficiency. Infants are also at risk of not receiving enough vitamin D. This is especially true for infants who are only fed breast milk, as it contains only a small amount of vitamin D.
    • Skin color: Its more difficult for dark-colored skin to make vitamin D from sunlight than light-colored skin, so people with darker skin are at a higher risk for vitamin D deficiency.
    • Mobility: People who are homebound or rarely go outside arent able to use sun exposure as a source of vitamin D. Thus, theyre at a higher risk for vitamin D deficiency.

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    When Should I Get A Vitamin D Test

    Vitamin D testing is ordered to determine if a deficiency, insufficiency, or toxic level of vitamin D is present or to monitor treatment for a previously diagnosed deficiency.

    Your health care provider may order a vitamin D blood test for you if you are experiencing symptoms of a vitamin D deficiency, such as:

    • Weakening of the bones
    • History of weight loss surgery
    • Reduced ability to make vitamin D in the skin due to limited sun exposure, sunscreen use, or dark skin pigmentation
    • Digestive diseases that make it difficult to absorb nutrients from food, including celiac disease and Crohnâs disease
    • Kidney and liver disease
    • Use of certain medications

    Vitamin D tests may also be ordered if your health care provider suspects that you may have abnormally high vitamin D levels, known as vitamin D toxicity. This occurs as a result of taking too much vitamin D in supplements rather than from too much sun exposure or dietary intake.

    Excess vitamin D in supplement form may cause your body to absorb more calcium from food and to reabsorb calcium from the bones into the blood. This results in excess calcium in the blood, also known as hypercalcemia, which can lead to symptoms like fatigue, confusion, bone pain, nausea and vomiting, frequent urination, and kidney problems.

    A health care provider who is familiar with your medical history is in the best position to determine whether you might benefit from vitamin D testing.

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