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Vitamin D total concentration (serum/plasma)

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

This test measures your total vitamin D levels in your blood. Vitamin D is important for bone health, muscle function, and immune support.

Quick summary

["Checks if you have enough vitamin D for your body’s needs."]

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

Key facts at a glance

LOINC
44200-4
Short code
Deprecated Sinuses XR 1V or 2V Ltd
Synonyms
Deprecated Sinuses XR 1V or 2V Ltd
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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 This Test Matters

Vitamin D helps your body absorb calcium, which is crucial for keeping bones strong. Low levels can lead to conditions like osteoporosis or muscle weakness. Some people may not get enough vitamin D from sunlight, diet, or supplements.

What to Expect Before the Test

You’ll likely have a simple blood draw from a vein in your arm. No special preparation is usually needed, but check with your provider if you’re on certain medications.

Common Causes of Low or High Levels

Low vitamin D can result from limited sun exposure, certain medical conditions (like kidney or liver disease), or poor diet. High levels may occur from over-supplementation or rare genetic disorders.

What the Results Mean

Results help doctors diagnose deficiencies or excesses. They guide decisions about diet, supplements, or further testing if needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin D levels are critical for preventing bone diseases, supporting immune function, and maintaining overall health. Your provider may recommend this test if you have symptoms like fatigue, bone pain, or frequent infections.

Short name

Vitamin D Level

Frequently asked questions

How often should I get this test?
Your provider will determine the best timing based on your health status, symptoms, and risk factors. Some people get it once a year, while others may need it more often.
Can I take supplements before the test?
Yes, but check with your provider first. If you’re taking vitamin D supplements, they may want to know the dose to adjust testing or interpretation.
What symptoms might indicate low vitamin D?
Common signs include fatigue, muscle weakness, bone pain, frequent illnesses, or mood changes. These aren’t always linked to vitamin D alone, so blood testing is the best way to confirm.
  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