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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, 1,25-Dihydroxy, LC/MS/MS #16558

3 Biomarkers - Specimen Type: Serum - Process Time*: Average 5 to 6 business days

*Important Information on Lab Test Processing Times: Foxx Lab Tests is committed to informing you about the processing times for your lab tests processed through Quest Diagnostics. Please note that the estimated processing time for each test, indicated in business days, is based on data from the past 30 days across the 13 Quest Diagnostics laboratories for each test. These estimates are intended to serve as a guide and are not guarantees. Factors such as laboratory workload, weather conditions, holidays, and the need for additional testing or maintenance can influence actual processing times. We aim to offer estimates to help you plan accordingly. Please understand that these times may vary, and processing times are not guaranteed. Thank you for choosing Ulta Lab Tests for your laboratory needs.

The Vitamin D, 1,25-Dihydroxy, LC/MS/MS test contains 1 test with 3 biomarkers.

Brief Description: The Vitamin D, 1,25-Dihydroxyvitamin test is a laboratory test that measures the level of 1,25-dihydroxyvitamin D in the blood. 1,25-dihydroxyvitamin D is the active form of vitamin D, and this test provides valuable information about the body's overall vitamin D status and its ability to regulate calcium and phosphorus levels.

Also Known As: Calcitriol Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

When is a Vitamin D 1,25-Dihydroxy test ordered?

A Vitamin D, 1,25-Dihydroxyvitamin test may be ordered in the following situations:

Evaluation of Calcium and Phosphorus Imbalances: When there are abnormalities in blood calcium and phosphorus levels, a Vitamin D, 1,25-Dihydroxyvitamin test may be ordered to assess the underlying cause. Vitamin D plays a crucial role in the regulation of calcium and phosphorus absorption and utilization in the body.

Monitoring of Kidney Function: The kidneys play a key role in the production and activation of 1,25-dihydroxyvitamin D. A Vitamin D, 1,25-Dihydroxyvitamin test may be ordered to evaluate kidney function and assess the body's ability to produce active vitamin D.

Evaluation of Vitamin D Disorders: This test may be used to evaluate disorders related to vitamin D metabolism, such as vitamin D-dependent rickets, renal osteodystrophy, or other conditions that affect the conversion of vitamin D to its active form.

What does a Vitamin D 1,25-Dihydroxy 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 are two separate kinds of vitamin D with somewhat different chemical 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.

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.

Lab tests often ordered with a Vitamin D 1,25-Dihydroxy test:

When a Vitamin D 1,25-Dihydroxy test is ordered, it's typically part of a broader evaluation of bone health, vitamin D status, or related conditions. Here are some tests commonly ordered alongside it:

Serum Calcium:

Purpose: To measure the level of calcium in the blood.

Why Is It Ordered: To assess calcium metabolism and evaluate for conditions like hypercalcemia or hypocalcemia, which can be related to abnormal vitamin D metabolism.


Purpose: To measure the level of phosphorus in the blood.

Why Is It Ordered: Phosphorus levels can be affected by vitamin D metabolism and are important in evaluating parathyroid gland function and bone health.

Vitamin D 25-Hydroxy (Calcidiol) Test:

Purpose: To measure the storage form of vitamin D in the body.

Why Is It Ordered: To evaluate overall vitamin D status, which is important for bone health and immune function.

Parathyroid Hormone (PTH):

Purpose: To measure the level of PTH, which regulates calcium and phosphate levels in the blood.

Why Is It Ordered: To assess parathyroid function, as disorders of the parathyroid glands can affect vitamin D metabolism and calcium/phosphorus balance.

Kidney Function Test:

Purpose: To evaluate kidney function.

Why Is It Ordered: The kidneys convert 25-hydroxyvitamin D into its active form, 1,25-dihydroxyvitamin D; thus, kidney function affects vitamin D metabolism.

Alkaline Phosphatase (ALP):

Purpose: To measure ALP, an enzyme related to bone activity.

Why Is It Ordered: Elevated ALP can indicate bone disorders, which may be related to vitamin D metabolism.

Magnesium Level:

Purpose: To measure the level of magnesium in the blood.

Why Is It Ordered: Magnesium is important for vitamin D metabolism, and deficiencies can affect vitamin D function.

These tests, when ordered alongside a Vitamin D 1,25-Dihydroxy test, provide a comprehensive view of an individual’s bone health, vitamin D status, and related metabolic functions. They are critical for diagnosing, managing, and monitoring conditions related to bone metabolism, kidney function, and disorders of calcium regulation. The specific combination of tests will depend on the individual's symptoms, medical history, and initial test results.

Conditions where a Vitamin D 1,25-Dihydroxy test is recommended:

A Vitamin D, 1,25-Dihydroxyvitamin test may be required in the following conditions or situations:

Vitamin D Deficiency or Insufficiency: When there is suspicion of vitamin D deficiency or insufficiency, this test helps determine if there is adequate production and activation of vitamin D in the body.

Kidney Disease: Kidney dysfunction can impair the production and activation of vitamin D, leading to low levels of 1,25-dihydroxyvitamin D. The test helps assess kidney function and identify underlying causes of abnormal vitamin D metabolism.

Rickets and Osteomalacia

Vitamin D, 1,25-Dihydroxy, LC/MS/MS

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