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

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

This test measures your body’s level of vitamin D, an important nutrient that helps your bones stay strong and supports overall health.

Quick summary

["Vitamin D levels help assess whether you’re getting enough of this essential nutrient."]

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

Key facts at a glance

LOINC
40667-8
Short code
RUBV IgG SerPl Ql IA
Synonyms
RUBV IgG SerPl 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 It’s Done

Your doctor may order this test if you have symptoms like muscle weakness, bone pain, or if you’re at higher risk for vitamin D deficiency, such as living far from the equator, having limited sun exposure, or having certain medical conditions that affect vitamin D absorption.

What to Expect

A blood sample is taken from a vein in your arm. You may feel a small pinch, but it usually doesn’t cause significant discomfort. The test is quick and doesn’t require special preparation.

How Results Are Interpreted

Results are compared to standard ranges, but exact values can vary by lab. Low levels may indicate deficiency, while higher levels might suggest over-supplementation or other conditions.

Common Conditions Linked to Results

Low vitamin D levels can contribute to conditions like osteoporosis, muscle weakness, or increased risk of certain infections. High levels may raise concerns about over-supplementation or metabolic issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin D level

Frequently asked questions

What causes vitamin D deficiency?
Vitamin D deficiency can result from limited sun exposure, poor diet, certain medical conditions (like malabsorption disorders), or medications that interfere with its production or use in the body.
How long does it take to get vitamin D test results?
Results are typically available within 1 to 3 business days, depending on your lab and healthcare provider. Follow-up may be needed if results are outside expected ranges.
Can vitamin D levels change quickly?
Yes, vitamin D levels can fluctuate due to changes in sun exposure, diet, or supplements. Regular monitoring may be recommended for those with ongoing health concerns or risk factors.
  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