Vitamin D, 25-Hydroxy (Total)
This test measures the total amount of vitamin D in your blood, which is an important nutrient for bone health and immune function.
["Your blood vitamin D levels help ensure proper bone health and support immune system function."]
Key facts at a glance
- LOINC
- 31891-5
- Short code
- MuV Ag Vag Ql
- Synonyms
- MuV Ag Vag Ql
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like muscle weakness, bone pain, or frequent illnesses. It could also be part of a routine check for conditions like osteoporosis, rickets, or vitamin D deficiency.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a fasting protocol. Wear a loose shirt for easy access to your arm.
What the Test Involves
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the procedure usually takes just a few minutes.
What the Results Mean
Results are compared to standard reference ranges, but your doctor will interpret them in the context of your overall health. Low levels may indicate deficiency, while very high levels could signal over-supplementation or certain medical conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Total 25-Hydroxy Vitamin D
Frequently asked questions
What are the normal reference ranges for this test?
How long does it take to get my results?
Can I take vitamin D supplements before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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