Skip to content

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 helps your body use calcium and maintain strong bones. Low levels may indicate deficiency, which can affect bone health and other body functions.

Quick summary

["Check your vitamin D levels to prevent deficiency and support overall health."]

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

Key facts at a glance

LOINC
14552-4
Short code
MuV Ag Vag Ql IF
Synonyms
MuV Ag Vag 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
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 if you have symptoms like fatigue, muscle pain, or bone pain, or if you have risk factors for vitamin D deficiency, such as limited sun exposure, certain medical conditions, or limited dietary intake of vitamin D-rich foods.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Bring any medications you’re currently taking to your appointment.

How the Test Is Performed

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure is quick and usually painless. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results are reported as a concentration of vitamin D in the blood. While reference ranges vary slightly by lab, low levels may suggest deficiency, while higher levels may indicate over-supplementation or other conditions. Your provider will interpret results in the context of your health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin D level

Frequently asked questions

What Does a Low Vitamin D Level Indicate?
Low levels of vitamin D can lead to weakened bones (osteomalacia or rickets in children), increased risk of fractures, muscle weakness, fatigue, and weakened immune function. Chronic deficiency may also be linked to other health concerns like depression or certain autoimmune conditions.
What Does a High Vitamin D Level Indicate?
High levels of vitamin D can sometimes indicate over-supplementation, kidney disease, or other metabolic issues. Your provider will assess results alongside your symptoms and medical history to determine if further testing or adjustments are needed.
How Often Should I Get This Test?
The frequency depends on your health status. People with risk factors (e.g., limited sun exposure, malabsorption disorders) may need testing every 1–2 years. Pregnant individuals or those with known deficiencies may need more frequent monitoring.
  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