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Vitamin D, 25-Hydroxy [Mass Concentration]

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

This test measures the level of vitamin D in your blood, specifically the form that your body converts from sunlight exposure or dietary sources. It helps assess whether you have enough vitamin D to support bone health and other bodily functions.

Quick summary

["Vitamin D levels are crucial for bone health and overall well-being."]

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

Key facts at a glance

LOINC
82731-1
Short code
ZIKV IgM Ser Ql IF
Synonyms
ZIKV IgM Ser 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
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 sufficient vitamin D, which is important for preventing conditions like rickets (in children) or osteoporosis (in adults). It’s often recommended for people with limited sun exposure, darker skin tones, or certain medical conditions that affect vitamin D absorption.

What Does a Low or High Level Mean?

Low levels may indicate vitamin D deficiency, which can lead to weak bones, muscle pain, or fatigue. High levels might suggest toxicity, though this is rare and usually requires medical attention.

How Is This 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-hydroxy vitamin D, the form stored in your bloodstream for long-term use.

What Are Common Causes of Abnormal Results?

Factors like limited sun exposure, poor diet, certain medications (e.g., anticonvulsants), or conditions affecting fat absorption (like celiac disease) can influence vitamin D levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

25-Hydroxy Vitamin D

Frequently asked questions

What if my vitamin D level is low?
If your level is low, your doctor may recommend dietary changes (e.g., fortified foods, fatty fish) or supplements (vitamin D3) under medical supervision.
How often should I get this test?
Frequency depends on your health status. People with risk factors (e.g., limited sun exposure, chronic illness) may need testing every 6–12 months.
Does diet affect this test result?
Yes, foods rich in vitamin D (e.g., fatty fish, fortified dairy) or supplements can influence results. Avoiding them for a few days before testing helps ensure accuracy.
  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