BiomarkersIonised calcium
Minerals
Ionised calcium
The active, free form of calcium in blood
On your report it may say: Ionized calcium, Ca++
Ionised calcium is the free, active form of calcium in your blood. It's more precise than total calcium when blood protein levels are abnormal.
Typical ranges · mmol/L
mg/dL = mmol/L × 4
The sample must be handled carefully; delays can change the result.
Ranges vary by lab, age and sex. The range printed on your report applies.
If it's low
Active calcium is low, which can affect nerves and muscles.
Common causes
- Low vitamin D or magnesium
- Parathyroid problems
- Kidney disease
What you might notice
- Tingling
- Cramps
- Spasms
If it's high
Active calcium is high and needs medical review.
Common causes
- Overactive parathyroid
- Excess vitamin D
What you might notice
- Thirst
- Constipation
- Tiredness
Testing
- Who should test
- When total calcium is borderline or protein levels are abnormal.
- How to prepare
- Follow lab instructions; usually fasting.
- When to retest
- As your doctor advises.
What can help
Food sources
See a doctor about any abnormal result.
Common questions
Why test ionised calcium?
It isn't affected by blood protein levels.
Is it routine?
No, it's usually ordered when total calcium is unclear.
Explore further
Sources
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Build My Nutrition PlanFor general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.