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Serum Vitamin D (25-Hydroxyvitamin D) with Spiral Curve Analysis

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

This test measures your levels of vitamin D, a fat-soluble nutrient essential for bone health and immune function. The spiral curve analysis may help assess how your body processes or responds to vitamin D.

Quick summary

["Vitamin D levels help ensure your bones stay strong and support overall health."]

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

Key facts at a glance

LOINC
8788-2
Short code
LV SVI Spiral CT
Synonyms
LV SVI Spiral CT
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct-spiral
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 crucial for maintaining strong bones by helping your body absorb calcium. It also plays a role in supporting your immune system, muscle function, and cell growth. Low levels can lead to conditions like osteoporosis or weakened immunity.

What to Expect Before the Test

No special preparation is needed for this test. You’ll provide a blood sample, typically drawn from your arm. If you’re taking vitamin D supplements, check with your healthcare provider before the test to avoid potential interference.

What the Results Mean

Your results will show your current vitamin D level. A lower level may indicate insufficient vitamin D, while higher levels may suggest excess intake or metabolic changes. Your doctor will interpret these results in the context of your overall health.

Common Causes of Low or High Levels

Low vitamin D levels can result from limited sun exposure, poor diet, certain medical conditions (e.g., malabsorption), or medications. High levels may occur from overuse of supplements or certain liver/kidney disorders. Your doctor will discuss potential causes with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin D Level (25-OH Vitamin D)

Frequently asked questions

How often should I get this test?
Vitamin D levels are often checked if you have symptoms like fatigue, bone pain, or frequent infections. Your doctor may recommend testing every 1–2 years for adults, especially if you have risk factors like limited sun exposure or certain health conditions.
Can I take vitamin D supplements without checking my levels first?
It’s best to avoid high-dose supplements without consulting your doctor, as vitamin D can accumulate in your body. Your test results will guide whether you need adjustments to your intake.
Does this test include any additional tests or analyses?
The spiral curve analysis may provide insights into how your body metabolizes vitamin D, but it’s not a standalone diagnostic tool. Your doctor will use these results alongside clinical judgment to guide treatment.
  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