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Vitamin D Blood Test Panel (25-Hydroxyvitamin D, 1,25-Dihydroxyvitamin D)

Published: August 9, 2026Updated: August 17, 2026

This panel measures two key forms of vitamin D in your blood to assess your overall vitamin D status.

Quick summary

["Your vitamin D levels help ensure strong bones and support immune function."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
72034-2
Short code
VITAMINDPANEL
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
30
Ref high
100
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
esrd
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 is essential for bone health, immune function, and muscle strength. Your body produces vitamin D when skin is exposed to sunlight, but diet and absorption can vary. This panel evaluates two critical forms of vitamin D: 25-hydroxyvitamin D (the primary blood test for vitamin D levels) and 1,25-dihydroxyvitamin D (an active form of vitamin D). Low levels may indicate deficiencies linked to bone problems, immune issues, or other health risks.

What to Expect Before the Test

No special preparation is needed. You may have a simple blood draw, usually from a vein in your arm. If you’re taking vitamin D supplements, your doctor may advise stopping them for a few days before testing to get an accurate reading.

What the Results Mean

Results show your levels of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. While exact ranges vary by lab, low levels may signal deficiency, while high levels could indicate over-supplementation or other conditions. Your doctor will interpret results in relation to your overall health and symptoms.

Common Causes of Low or High Levels

Low vitamin D levels can result from limited sun exposure, poor diet, digestive issues, or certain medical conditions. High levels may stem from over-supplementation, kidney problems, or rare genetic disorders. Your doctor may recommend lifestyle changes, diet adjustments, or supplements based on your results.

Reference range

NCBI: Vitamin D 30-100 ng/mL (sufficient)N/A

Specimen: serum

Fasting for 8-12 hours preferred for some tests. Inform about supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin D Blood Check

Frequently asked questions

How Might My Doctor Use These Results?
Your doctor may use these results to diagnose or monitor conditions like osteoporosis, rickets, immune disorders, or muscle weakness. Vitamin D deficiency is also linked to fatigue, frequent infections, and other systemic health concerns. If you have symptoms like bone pain, frequent illnesses, or unexplained fatigue, this test can help identify if vitamin D is a contributing factor.
What If My Results Are Out of Range?
If your levels are low, your doctor may recommend increasing sun exposure, dietary changes (e.g., fatty fish, fortified foods), or supplements under medical supervision. If levels are high, they may investigate underlying causes like kidney disease or over-supplementation and adjust treatment accordingly.
Do I Need This Test?
This test is often recommended for people with risk factors like limited sun exposure, dark skin, certain medical conditions, or pregnancy. Your doctor may also order it if you have symptoms of vitamin D deficiency or if you’re taking supplements. Always ask your healthcare provider if this test is right for you.
  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 17, 2026. · Read our editorial policy