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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 overall well-being. Vitamin D helps your body absorb calcium and supports immune function.

Quick summary

["Vitamin D levels help assess your risk for bone-related conditions and overall health."]

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

Key facts at a glance

LOINC
69766-4
Short code
MuV IgM Fld Ql IA
Synonyms
MuV IgM Fld 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 recommend this test if you have symptoms of vitamin D deficiency, such as muscle weakness, bone pain, or frequent infections. It may also be ordered to monitor vitamin D levels in people at higher risk, such as those with limited sun exposure, certain medical conditions, or those taking medications that affect vitamin D absorption.

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 in the morning. Bring any medications or supplements you’re taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The process is quick and typically causes only minor discomfort. The blood sample is sent to a lab for analysis.

What Are the Results?

Results are reported as a numerical value representing the concentration of vitamin D in your blood. Your provider will interpret the results in relation to your health and medical history.

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 mean?
A low vitamin D level may indicate insufficient sun exposure, poor diet, certain medical conditions (like malabsorption disorders), or medications that interfere with vitamin D production. Your provider may suggest lifestyle changes, supplements, or further testing to address it.
How long does it take to get results?
Results are usually available within 1–3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the findings with you during your follow-up visit.
Can I take vitamin D supplements without checking my levels first?
It’s best to consult your provider before starting supplements. High doses of vitamin D can be harmful if taken excessively, so monitoring your levels ensures safety and effectiveness.
  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