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Serum Calcium with 25-Hydroxy Vitamin D (25(OH)D) Ratio (for Bone Metabolism Screening)

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

This test measures the ratio of calcium and vitamin D levels in your blood to help assess bone health and overall mineral balance.

Quick summary

["A ratio helps identify potential imbalances affecting bones and metabolism."]

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

Key facts at a glance

LOINC
24946-6
Short code
XR C-spine Views
Synonyms
XR C-spine Views
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 Is Done

Your doctor may order this test if you have symptoms like bone pain, frequent fractures, or signs of vitamin D deficiency. It’s also used in screening for conditions like osteoporosis or metabolic bone diseases.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your vein (usually in your arm) to draw blood. It usually takes a few minutes.

What the Results Mean

The ratio compares calcium and vitamin D levels to check if either is too high or too low. Abnormal results may signal conditions like hypocalcemia, hypercalcemia, or vitamin D deficiency.

Common Conditions Linked to These Results

High or low ratios can indicate bone disorders, kidney issues, or thyroid problems. Vitamin D is crucial for calcium absorption, so imbalances may affect bone strength and overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Calcium/Vitamin D Ratio

Frequently asked questions

What does a ‘normal’ ratio mean for me?
A ‘normal’ ratio doesn’t have a single number—it’s a comparison. Your doctor will interpret it based on your health history, symptoms, and other test results. They’ll explain what your specific ratio means for your care.
Can diet or supplements affect this test?
Yes! Foods rich in calcium (like dairy) or vitamin D (like fatty fish) can influence results. Avoiding large calcium supplements for 48 hours before testing may help get more accurate results.
How often should I get this test?
Your doctor will determine how often you need this test based on your health needs, such as whether you have a history of bone issues or vitamin D deficiency.
  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