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Vitamin D, 25-Hydroxy (Total)

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

This test measures the total amount of vitamin D in your blood, which is an important indicator of your vitamin D status.

Quick summary

["Vitamin D helps maintain bone health and supports immune function; low levels may indicate deficiency."]

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

Key facts at a glance

LOINC
36779-7
Short code
MR Ovary
Synonyms
MR Ovary
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mr
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 essential for bone health, muscle function, and immune support. It’s often recommended for people who don’t get enough sunlight, have limited sun exposure, or have conditions that affect vitamin D absorption.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the blood draw if your lab requires it. Wear a comfortable shirt for easy access to your arm.

What Happens During the Test?

A healthcare professional will insert a small needle into your arm to draw blood. You may feel a slight pinch, but the process is quick. The blood is then sent to a lab for analysis.

What Are the Results Meaning?

Results show your total vitamin D level, which helps determine if you’re deficient, sufficient, or in excess. Your provider will interpret the results in relation to your health needs and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low levels of vitamin D can lead to bone disorders (like osteoporosis or rickets), muscle weakness, or weakened immunity. High levels may cause calcium buildup in organs or kidney issues. Regular monitoring helps manage vitamin D levels effectively.

Short name

Total 25-Hydroxyvitamin D

Frequently asked questions

How often should I get this test?
Your provider will decide based on your health status, symptoms, and risk factors (e.g., limited sun exposure, certain medical conditions). Typically, it’s done once or twice a year for maintenance.
What causes vitamin D deficiency?
Vitamin D deficiency can result from limited sun exposure, poor diet (low in fatty fish, fortified foods), certain medications, or conditions affecting digestion or absorption (e.g., celiac disease, Crohn’s).
Can I boost my vitamin D levels without testing?
Yes, you can increase vitamin D through sunlight exposure (10–30 minutes of midday sun), dietary sources (salmon, eggs, fortified milk), or supplements (under medical guidance). Always check with your provider before starting supplements.
  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