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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 helps your body absorb calcium and maintain bone health. Low levels may indicate deficiency, which can affect muscle function, bone strength, and overall health.

Quick summary

["Vitamin D levels help assess your risk for deficiency and related health issues."]

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

Key facts at a glance

LOINC
11077-5
Short code
HCV SOD Ab Ser Ql IB
Synonyms
HCV SOD Ab Ser Ql IB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
CPT
86803
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 of vitamin D deficiency, such as muscle weakness, bone pain, or frequent infections. It may also be used to monitor vitamin D levels in people who take vitamin D supplements or have conditions that affect vitamin D absorption, like kidney disease or malabsorption disorders.

What Does a Low or High Level Mean?

Low levels of vitamin D may suggest deficiency, which can lead to weakened bones, muscle pain, or an increased risk of certain health problems. High levels might indicate over-supplementation or other underlying conditions that require further evaluation.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it is analyzed to measure the concentration of 25-hydroxyvitamin D, a form of vitamin D that reflects your body’s overall vitamin D status.

What Are the Possible Results?

Results are typically reported as a numerical value representing the concentration of vitamin D in the blood. Your healthcare provider will interpret the results in relation to your symptoms, medical history, and other test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin D level (25-OH vitamin D)

Frequently asked questions

What causes vitamin D levels to be low?
Vitamin D deficiency can be caused by limited sun exposure, poor diet (low intake of fatty fish, fortified foods, or supplements), certain medical conditions (like celiac disease or Crohn’s), or medications that interfere with vitamin D absorption.
How often should I get this test?
The frequency depends on your health status. People with known deficiency, certain medical conditions, or those taking vitamin D supplements may need testing more often, often every 6–12 months. Your provider will determine the best schedule for you.
Can vitamin D levels be affected by diet alone?
Diet can influence vitamin D levels, but blood tests are the most accurate way to measure your status. While foods like salmon, fortified milk, and egg yolks contain vitamin D, absorption can vary, and sunlight exposure also plays a key role in producing vitamin D in your skin.
  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