Vitamin D, 25-Hydroxyvitamin D (D2, D3), LC/MS/MS (QuestAssureD™) Most Popular

The Vitamin D, 25-Hydroxyvitamin D (D2, D3), LC/MS/MS (QuestAssureD™) test contains 1 test with 6 biomarkers.

Brief Description: The QuestAssureD Vitamin D test is a specialty Vitamin D test that measures the total level of Vitamin D in the blood along with Vitamin D2 and D3. It is a reliable and accurate method of assessing Vitamin D status.

Also Known As: Ergocalciferol Test, Vitamin D2 Test, Cholecalciferol Test, Vitamin D3 Test, Calcidiol Test, 25-hydroxyvitamin D Test, Calcifidiol Test, 25-hydroxy-vitamin D Test, Vitamin D Total Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: Fasting preferred, but not required.

When is a Vitamin D test ordered?

The QuestAssureD Vitamin D test may be ordered in various situations:

  1. Vitamin D Deficiency or Insufficiency Screening: It is commonly ordered to evaluate an individual's Vitamin D status and determine if they have a deficiency or insufficiency. This is particularly important for those at higher risk, such as individuals with limited sun exposure, older adults, individuals with dark skin, or those with certain medical conditions.

  2. Monitoring Vitamin D Supplementation: For individuals who are taking Vitamin D supplements, the test helps monitor their response to supplementation and ensures that their Vitamin D levels are within the desired range.

  3. Evaluating Bone Health: Since Vitamin D plays a crucial role in calcium absorption and bone health, the test may be ordered as part of an evaluation for conditions such as osteoporosis or osteomalacia.

What does a Vitamin D blood test check for?

Vitamin D is a group of chemicals that are necessary for the healthy development and growth of teeth and bones. The level of vitamin D in the blood is determined by this test.

Vitamin D is tested in the blood in two forms: 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. The primary form of vitamin D found in the blood is 25-hydroxyvitamin D, which is a relatively inactive precursor to the active hormone 1,25-dihydroxyvitamin D. 25-hydroxyvitamin D is routinely evaluated to assess and monitor vitamin D status in humans due to its longer half-life and higher concentration.

Endogenous vitamin D is created in the skin when exposed to sunshine, whereas exogenous vitamin D is taken through foods and supplements. Vitamin D2 and vitamin D3 have somewhat different molecular structures. Fortified foods, as well as most vitamin preparations and supplements, include the D2 form. The type of vitamin D3 produced by the body is also used in some supplements. When the liver and kidneys convert vitamin D2 and D3 into the active form, 1,25-dihydroxyvitamin D, they are equally effective.

Some tests may not differentiate between the D2 and D3 forms of vitamin D and just report the total result. Newer methods, on the other hand, may record D2 and D3 levels separately and then sum them up to get a total level.

Vitamin D's major function is to assist balance calcium, phosphorus, and magnesium levels in the blood. Vitamin D is necessary for bone growth and health; without it, bones become fragile, misshapen, and unable to mend themselves properly, leading to disorders such as rickets in children and osteomalacia in adults. Vitamin D has also been proven to influence the growth and differentiation of a variety of other tissues, as well as to aid in immune system regulation. Other illnesses, such as autoimmune and cancer, have been linked to vitamin D's other roles.

According to the Centers for Disease Control and Prevention, two-thirds of the US population has adequate vitamin D, while one-quarter is at risk of inadequate vitamin D and 8% is at risk of insufficiency, as defined by the Institute of Medicine's Dietary Reference Intake.

The elderly or obese, persons who don't receive enough sun exposure, people with darker skin, and people who take certain drugs for lengthy periods of time are all at risk of insufficiency. Adequate sun exposure is usually defined as two intervals of 5-20 minutes each week. Vitamin D can be obtained through dietary sources or supplements by people who do not get enough sun exposure.

This test has 3 Biomarkers

  • Vitamin D Total which is a combined measurement of Vitamin D, 25-Oh, D2 and Vitamin 25-Oh, D3
  • Vitamin D, 25-Oh, D2 which is a measurement of ergocalciferol Vitamin D, which is Vitamin D obtained through plant sources. 
  • Vitamin D, 25-Oh, D3 which is a measurement of cholecalciferol Vitamin D, which is Vitamin D obtained through animal sources.

Lab tests often ordered with a Vitamin D test:

Alongside this test, several other tests might be ordered to evaluate related health aspects:

  1. Calcium (Ca):

    • Purpose: Vitamin D plays a significant role in calcium absorption and bone health.
    • Why Is It Ordered: To check for abnormalities in calcium levels that might be associated with vitamin D deficiency or excess, which could affect bone health and other physiological functions.
  2. Phosphorus/Phosphate (PO4):

    • Purpose: Vitamin D is also involved in phosphorus regulation.
    • Why Is It Ordered: To assess bone metabolism and renal function, especially if a vitamin D deficiency or excess is suspected to be impacting these areas.
  3. Parathyroid Hormone (PTH):

    • Purpose: PTH helps regulate calcium and vitamin D levels in the body.
    • Why Is It Ordered: To investigate parathyroid function and differentiate between primary hyperparathyroidism and secondary hyperparathyroidism, which may result from a vitamin D deficiency.
  4. Alkaline Phosphatase (ALP):

    • Purpose: ALP can be elevated in conditions affecting the bones.
    • Why Is It Ordered: To evaluate bone metabolism, particularly in cases where vitamin D deficiency is suspected to be affecting bone turnover and health.
  5. Kidney Function Test:

    • Purpose: Since the kidney is involved in converting vitamin D to its active form, kidney function is important for vitamin D metabolism.
    • Why Is It Ordered: To evaluate whether kidney disease might be affecting vitamin D metabolism.
  6. Magnesium:

    • Purpose: Magnesium is important for vitamin D metabolism.
    • Why Is It Ordered: To rule out magnesium deficiency, which can affect vitamin D status and function.
  7. 1,25-Dihydroxyvitamin D:

    • Purpose: This is the active form of vitamin D, produced in the kidneys.
    • Why Is It Ordered: In certain conditions, such as kidney disease or granulomatous diseases like sarcoidosis, measuring the active form of vitamin D can provide more specific information about vitamin D status and metabolism.

These additional tests can help to determine the underlying cause of abnormal vitamin D levels, assess for bone health, evaluate the risk of osteoporosis, and guide appropriate treatment and supplementation. The specific tests ordered will depend on the individual’s clinical scenario and initial test results.

Conditions where a Vitamin D test is recommended:

The QuestAssureD Vitamin D test is helpful in various conditions, including:

  1. Vitamin D Deficiency or Insufficiency: The test is ordered to diagnose and monitor individuals with low Vitamin D levels, which can lead to conditions like rickets (in children) or osteomalacia (in adults).

  2. Osteoporosis or Osteopenia: Vitamin D deficiency is associated with reduced bone density and increased risk of osteoporosis. Testing Vitamin D levels can help identify individuals who may require additional interventions to improve bone health.

  3. Chronic Kidney Disease: Individuals with chronic kidney disease often have impaired Vitamin D metabolism and are at increased risk of Vitamin D deficiency. The test aids in monitoring their Vitamin D status and guiding appropriate treatment.

How does my healthcare provider use a Vitamin D test?

Healthcare providers use the results of the QuestAssureD Vitamin D test to:

  1. Determine Vitamin D Status: The test helps identify individuals with Vitamin D deficiency, insufficiency, or sufficiency based on established reference ranges.

  2. Guide Treatment Decisions: For individuals with low Vitamin D levels, the test results assist healthcare providers in determining the appropriate Vitamin D supplementation dosage and frequency.

  3. Monitor Response to Treatment: The QuestAssureD Vitamin D test allows healthcare providers to evaluate the effectiveness of Vitamin D supplementation or sunlight exposure interventions and make adjustments as needed to optimize Vitamin D levels.

It is important to note that the interpretation and utilization of the QuestAssureD Vitamin D test results should be done in consultation with a healthcare provider who can consider the individual's specific clinical situation, medical history, and other relevant factors.

What do my Vitamin D results result mean?

Despite the fact that vitamin D techniques differ, most laboratories use the same reference intervals. Because toxicity is uncommon, researchers have focused on the lower limit and what cut-off for total 25-hydroxyvitamin D shortage implies.

A low blood level of 25-hydroxyvitamin D could indicate that a person isn't getting enough sunlight or dietary vitamin D to meet his or her body's needs, or that there's an issue with absorption from the intestines. Seizure medications, notably phenytoin, might occasionally interfere with the liver's generation of 25-hydroxyvitamin D.

Vitamin D insufficiency has been linked to an increased risk of some malignancies, immunological illnesses, and cardiovascular disease.

Excessive supplementation with vitamin pills or other nutritional supplements frequently results in a high level of 25-hydroxyvitamin D.

Most Common Questions About the Vitamin D 25-Hydroxyvitamin D2 D3 test:

Understanding the Test

What is the Vitamin D 25-Hydroxyvitamin D2 D3 test?

The Vitamin D 25-Hydroxyvitamin D2 D3 test is a blood test that measures the amount of vitamin D in your body. It quantifies the levels of both D2 and D3, the two major forms of vitamin D, to assess your overall vitamin D status.

What does the Vitamin D 25-Hydroxyvitamin D2 D3 test measure?

This test measures the levels of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in your blood. These are the forms of vitamin D that your body makes when it absorbs vitamin D from food, supplements, or when your skin absorbs sunlight.

Interpreting the Results

What can an abnormal result in the Vitamin D 25-Hydroxyvitamin D2 D3 test mean?

Abnormally low levels of vitamin D might suggest inadequate intake, poor absorption from the intestines, or insufficient conversion in the liver. Low levels can lead to problems like rickets in children or osteomalacia in adults. High levels, although less common, could indicate excessive intake of vitamin D, which can lead to hypercalcemia and other complications.

What does it mean if my Vitamin D 25-Hydroxyvitamin D2 D3 test shows low levels of Vitamin D?

Low levels of Vitamin D could mean that you are not getting enough exposure to sunlight, your diet lacks sufficient Vitamin D, or your body is having trouble absorbing this vitamin from the food you eat. It could also mean your liver or kidneys aren't converting the vitamin D to its active form efficiently.

About the Test

Can certain medications affect the results of the Vitamin D 25-Hydroxyvitamin D2 D3 test?

Yes, certain medications can affect your vitamin D levels and thus the test results. Some drugs, such as phenytoin, phenobarbital, and rifampin, can lower your vitamin D levels, while others like thiazide diuretics can increase them.

Does the Vitamin D 25-Hydroxyvitamin D2 D3 test differentiate between the two forms of Vitamin D?

Yes, the test separately quantifies the levels of 25-hydroxyvitamin D2 and D3, allowing your healthcare provider to evaluate your overall vitamin D status more accurately.

Understanding the Implications

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test be used to monitor certain medical conditions?

Yes, the test can be used to monitor conditions that affect the metabolism of vitamin D, such as hyperparathyroidism, rickets, osteoporosis, malabsorption syndromes, and kidney disease.

What role does the liver and kidney play in the Vitamin D 25-Hydroxyvitamin D2 D3 test?

The liver and kidneys are important for vitamin D metabolism. The liver converts vitamin D to 25-hydroxyvitamin D, which is then converted by the kidneys to the active form, calcitriol. Disorders of the liver or kidneys can disrupt these processes and affect your vitamin D levels.

Risks and Precautions

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test detect bone health issues?

Yes, the test can help evaluate bone health. Low levels of vitamin D can cause low calcium and phosphate levels, leading to bone diseases like rickets in children and osteoporosis or osteomalacia in adults.

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test provide information about my risk for certain diseases?

Yes, research suggests that low levels of vitamin D may be associated with increased risks of certain diseases, including cardiovascular disease, cancer, diabetes, and autoimmune conditions, though more research is needed in these areas.

Dealing with Abnormal Results

What should I do if my Vitamin D 25-Hydroxyvitamin D2 D3 test shows abnormal results?

If your Vitamin D 25-Hydroxyvitamin D2 D3 test shows abnormal results, it's important to discuss these with your healthcare provider, who may recommend changes to your diet, sun exposure, or a vitamin D supplement. They may also recommend additional testing if they suspect an underlying condition is causing abnormal vitamin D levels.

Are there ways to improve abnormal results in the Vitamin D 25-Hydroxyvitamin D2 D3 test?

If your results show a deficiency, increasing your sun exposure, improving your diet, or taking vitamin D supplements can help raise your levels. If your vitamin D levels are too high, you may need to reduce your intake of vitamin D supplements or foods high in vitamin D. It's important to discuss these options with your healthcare provider.

Interpreting the Test Results

How are the results of the Vitamin D 25-Hydroxyvitamin D2 D3 test presented?

The results of the Vitamin D 25-Hydroxyvitamin D2 D3 test are usually presented in nanograms per milliliter (ng/mL) or nanomoles per liter (nmol/L). The acceptable range can vary slightly depending on the laboratory, but generally, a level of 20-50 ng/mL (or 50-125 nmol/L) is considered adequate for most people.

Can I have normal Vitamin D 25-Hydroxyvitamin D2 D3 test results and still have a vitamin D deficiency?

Although unlikely, it is possible if the body is not converting the 25-hydroxyvitamin D to its active form efficiently due to issues with the kidneys. A normal test can also sometimes miss cases of vitamin D deficiency if the levels have only recently fallen.

Understanding the Importance of the Test

How does the Vitamin D 25-Hydroxyvitamin D2 D3 test relate to calcium levels in the body?

Vitamin D is important for calcium absorption in the gut and for maintaining adequate serum calcium and phosphate concentrations to support metabolic functions and bone health. If you're deficient in vitamin D, you may have low levels of calcium, leading to bone diseases.

How can the Vitamin D 25-Hydroxyvitamin D2 D3 test help me understand my risk for osteoporosis?

Low levels of vitamin D can lead to decreased calcium absorption, and this can increase your risk of osteoporosis. Measuring your vitamin D levels can help determine if low calcium intake or poor vitamin D status may be contributing to bone loss.

Discussion with Healthcare Provider

What should I discuss with my healthcare provider before getting the Vitamin D 25-Hydroxyvitamin D2 D3 test?

You should discuss any symptoms you're experiencing, your overall diet, how much time you spend outdoors, whether you're taking any vitamin D supplements, and any medications you're currently on, as these factors can influence your vitamin D levels.

What questions should I ask my healthcare provider after getting the Vitamin D 25-Hydroxyvitamin D2 D3 test?

You might ask about the implications of your results, whether you need to adjust your diet or vitamin D supplement, and if you need any additional tests.

Future Considerations

How often should the Vitamin D 25-Hydroxyvitamin D2 D3 test be repeated?

The frequency of testing depends on your individual health circumstances. For those with deficiencies or certain health conditions, regular testing may be recommended to monitor the effectiveness of treatment.

What future medical tests might be needed if the Vitamin D 25-Hydroxyvitamin D2 D3 test reveals abnormal results?

If your Vitamin D 25-Hydroxyvitamin D2 D3 test results are abnormal, additional tests might be required to identify the underlying cause. These could include tests for parathyroid hormone levels, calcium levels, or tests to assess bone density.

General Questions

Why is it important to measure both forms of vitamin D in the Vitamin D 25-Hydroxyvitamin D2 D3 test?

Vitamin D2 and D3 are both important for health, but they come from different sources and their levels can vary independently. Measuring both gives a more complete picture of your overall vitamin D status.

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test tell me if I'm getting enough vitamin D from sunlight?

Yes, the test can help indicate if you're getting adequate vitamin D from sun exposure. If your levels are low, it might mean you're not getting enough sun, especially if your dietary intake of vitamin D is sufficient.

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test help diagnose autoimmune diseases?

Low levels of vitamin D have been associated with several autoimmune diseases like multiple sclerosis, rheumatoid arthritis, and type 1 diabetes. However, low vitamin D can be a result of the disease rather than its cause. Therefore, while the test can support a diagnosis, it cannot diagnose an autoimmune disease by itself.

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test detect potential deficiencies in vegans or vegetarians?

Yes, as most dietary sources of vitamin D come from animal products, vegans and vegetarians are at a higher risk of deficiency. This test can help assess their vitamin D status and determine if supplementation is needed.

Can the Vitamin D 25-Hydroxyvitamin D2 D3 test help in assessing my overall nutritional status?

Yes, vitamin D status is one important aspect of overall nutrition. Low levels could indicate a deficiency in your diet, a lack of sun exposure, issues with absorption, or problems with conversion to its active form. However, a comprehensive nutritional assessment would include other tests and evaluations as well.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Vitamin D, 25-Oh, D2

Vitamin D2 ((ergocalciferol,) is found in fortified foods and in most vitamin preparations and supplements. 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. The D2 form is found in fortified foods and in most vitamin preparations and supplements. Vitamin D2 is effective when it is converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.

Vitamin D, 25-Oh, D3

Vitamin D3 (cholecalcifero) which comes from animals. 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 D3 is the form produced in the body and is also used in some supplements. Vitamin D3 are is converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.

Vitamin D, 25-Oh, Total

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. The chemical structures of the types of vitamin D are slightly different, and they are named vitamin D2 (ergocalciferol, which comes from plants) and vitamin D3 (cholecalciferol, which comes from animals). The D2 form is found in fortified foods and in most vitamin preparations and supplements. Vitamin D3 is the form produced in the body and is also used in some supplements. Vitamin D2 and D3 are equally effective when they are converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.

Vitamin D, 25-Oh, Total

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. The chemical structures of the types of vitamin D are slightly different, and they are named vitamin D2 (ergocalciferol, which comes from plants) and vitamin D3 (cholecalciferol, which comes from animals). The D2 form is found in fortified foods and in most vitamin preparations and supplements. Vitamin D3 is the form produced in the body and is also used in some supplements. Vitamin D2 and D3 are equally effective when they are converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.

Vitamin D, 25-Oh, Total

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. The chemical structures of the types of vitamin D are slightly different, and they are named vitamin D2 (ergocalciferol, which comes from plants) and vitamin D3 (cholecalciferol, which comes from animals). The D2 form is found in fortified foods and in most vitamin preparations and supplements. Vitamin D3 is the form produced in the body and is also used in some supplements. Vitamin D2 and D3 are equally effective when they are converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.

Vitamin D, 25-Oh, Total

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. The chemical structures of the types of vitamin D are slightly different, and they are named vitamin D2 (ergocalciferol, which comes from plants) and vitamin D3 (cholecalciferol, which comes from animals). The D2 form is found in fortified foods and in most vitamin preparations and supplements. Vitamin D3 is the form produced in the body and is also used in some supplements. Vitamin D2 and D3 are equally effective when they are converted by the liver and the kidney into the active form, 1,25-dihydroxyvitamin D.
*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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