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Serum or plasma concentration of vitamin D (25-hydroxyvitamin D)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of vitamin D in your blood, which is important for bone health and other bodily functions.

Quick summary

["Vitamin D levels help ensure you have enough of this essential nutrient for strong bones and overall health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
41512-5
Short code
VZV IgG Ser Ql IF
Synonyms
VZV IgG Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check if you have enough vitamin D, which can help prevent conditions like osteoporosis or rickets. It may also be used to diagnose or monitor vitamin D deficiency or related issues, such as certain bone disorders or muscle weakness.

What to Expect Before the Test

No special preparation is usually needed. If you’re having blood drawn, you may be asked to fast for 8–12 hours before the test, depending on the lab’s instructions. Let your provider know about any medications you’re taking, as some may affect results.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The blood sample will be sent to a lab for analysis. The test measures the level of 25-hydroxyvitamin D, a form of vitamin D found in the blood.

What Are the Results?

Results are typically reported as a numerical value (in units like ng/mL or nmol/L), but your provider will interpret them based on your health and symptoms. Deficiency is often identified by lower-than-normal levels, while higher-than-normal levels may indicate overabsorption or certain conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin D level

Frequently asked questions

What Does a Low Vitamin D Level Mean?
A low vitamin D level may indicate deficiency, which can lead to weakened bones, muscle pain, fatigue, or increased risk of certain health problems. Your provider may recommend supplements or lifestyle changes to help correct it.
What Does a High Vitamin D Level Mean?
High levels can sometimes signal overabsorption, kidney issues, or other conditions. Your provider will discuss next steps based on your overall health and symptoms.
How Often Should I Get This Test?
Your provider will determine how often you need this test based on your age, health history, and risk factors (e.g., limited sun exposure, certain diets). Regular checks may be recommended if you have conditions like osteoporosis or kidney disease.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy