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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 level of vitamin D in your blood, which is important for bone health and other bodily functions.

Quick summary

["Vitamin D levels help assess your risk for deficiencies that may affect bones, muscles, or overall health."]

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

Key facts at a glance

LOINC
95527-8
Short code
CMV IgG Sal Ql IA
Synonyms
CMV IgG Sal Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 is needed for strong bones and to help your body absorb calcium. It can also be used to diagnose or monitor conditions like osteoporosis, muscle weakness, or certain autoimmune diseases.

What does the test involve?

A small blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it is analyzed to measure the amount of vitamin D in your serum or plasma.

What do the results mean?

Results are typically reported as a concentration of vitamin D in the blood. While specific ranges can vary, low levels may indicate a deficiency, while higher levels may suggest excess intake or certain medical conditions.

What can affect vitamin D levels?

Several factors can influence vitamin D levels, including sun exposure, diet (such as fatty fish or fortified foods), age, skin pigmentation, and certain medical conditions or medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin D blood test

Frequently asked questions

What are common causes of abnormal results?
Low vitamin D levels can be caused by insufficient sun exposure, poor diet, certain digestive disorders, or conditions that affect the kidneys or liver. High levels may result from over-supplementation or certain genetic conditions.
How often should I get this test?
The frequency depends on your health status, risk factors, and recommendations from your healthcare provider. Typically, it may be recommended annually for individuals at risk of deficiency.
What lifestyle changes can help maintain healthy vitamin D levels?
Increasing sun exposure, eating vitamin D-rich foods, and sometimes taking supplements (if advised by your doctor) can help maintain healthy levels. Always follow your healthcare provider’s guidance.
  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