Serum or plasma concentration of vitamin D (25-hydroxyvitamin D)
This test measures the amount of vitamin D in your blood, which helps your body absorb calcium and maintain strong bones. Low levels may indicate deficiency, while high levels could signal overabsorption or certain medical conditions.
["Vitamin D levels help prevent bone-related issues and support overall health."]
Key facts at a glance
- LOINC
- 109923-3
- Short code
- BKVCSF
- Synonyms
- BKV DNA Msmt CSF
- Category
- chemistry
- Sample
- csf
- Container
- Sterile, leak-proof polypropylene collection tube (screw-cap preferred) for CSF. Tube should be labeled with patient identifiers, collection date, and time. Transport at 2-8°C if not processed immediately.
- Units
- N/A
- Ref low
- 0
- Ref high
- 0
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Real-time Polymerase Chain Reaction (PCR), quantitative
- CPT
- 87799
- SNOMED
- 415070008
- Specimen volume
- Minimum 0.5 mL of CSF; 1-2 mL preferred for adequate testing
- Stability
- Room temperature: 4 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or lower): 3 months. Avoid repeated freeze-thaw cycles. Store at -70°C for long-term preservation.
- Hemolysis max
- 200
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to check for vitamin D deficiency, which can lead to weak bones (osteoporosis), muscle weakness, or other health problems. It may also be used to monitor vitamin D levels if you take supplements or have conditions like kidney disease that affect vitamin D metabolism.
What to Expect Before the Test
No special preparation is usually needed. If you’re having blood drawn, you may be asked to fast for 8–12 hours before the test, but this depends on your doctor’s instructions. If you’re tested for urine or other fluids, follow any specific guidelines provided.
What Happens During the Test?
Blood is drawn from a vein in your arm, and the sample is sent to a lab for analysis. If testing urine or saliva, you’ll collect a sample at home or in a clinic. The lab measures the specific form of vitamin D (25-hydroxyvitamin D) in your blood or fluid.
What Are Possible Results?
Results are reported in units of measurement (e.g., nanograms per deciliter, ng/dL), but your doctor will interpret them based on your health status. Very low or very high levels may require further evaluation.
Reference range
Not detected (Negative); Quantitative results reported in copies/mL or IU/mL. Reference range is typically negative in immunocompetent individuals. Please refer to laboratory-specific reference ranges.N/A
No special patient preparation is required. However, the lumbar puncture procedure should be explained to the patient, including potential risks such as headache, infection, or bleeding. Informed consent is typically required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Vitamin D level
Frequently asked questions
Low vitamin D levels may signal deficiency, which can cause fatigue, bone pain, or increased risk of fractures. It’s also linked to conditions like autoimmune diseases, certain cancers, and heart disease. High levels might suggest over-supplementation, liver/kidney issues, or rare metabolic disorders.
A low vitamin D level could mean you’re not getting enough sunlight, have limited sun exposure, or have dietary deficiencies. Your doctor may recommend lifestyle changes (like more sunlight or fortified foods) or supplements to help correct it.
Yes, vitamin D levels can fluctuate due to changes in sun exposure, diet, or health conditions. Regular monitoring may be needed if you have chronic illnesses or take certain medications that affect vitamin D metabolism.
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