BiomarkersCalcium (total)

Minerals

Calcium (total)

Blood calcium, tightly controlled by hormones

On your report it may say: Total calcium, Serum Ca

Blood calcium is kept in a narrow range by hormones and vitamin D. It doesn't show how much calcium you eat or how strong your bones are; abnormal results usually point to a hormone, kidney or vitamin D issue.

Updated 2026-10-26

Typical ranges · mg/dL

Low below 8.5
In range 8.5–10.5
High 10.5+

mmol/L = mg/dL × 0.25

Low albumin (a blood protein) lowers total calcium; doctors may correct for it or test ionised calcium.

Ranges vary by lab, age and sex. The range printed on your report applies.

If it's low

Calcium is below the normal range, often linked to low vitamin D, low magnesium or low protein.

Common causes

  • Low vitamin D
  • Low magnesium
  • Low albumin
  • Kidney disease
  • Parathyroid problems

What you might notice

  • Tingling around the mouth or fingers
  • Muscle cramps or spasms

If it's high

High calcium needs medical review; common causes include an overactive parathyroid or too much vitamin D.

Common causes

  • Overactive parathyroid gland
  • Too much vitamin D or calcium supplements
  • Some medicines
  • Other medical conditions

What you might notice

  • Thirst
  • Constipation
  • Tiredness
  • Kidney stones

Testing

Who should test
Part of routine metabolic panels; anyone taking high-dose vitamin D.
How to prepare
Often fasting; follow your lab's instructions.
When to retest
As your doctor advises.

What can help

Food sources

DairyRagiSesame seedsLeafy greens

See a doctor about any result outside the range, especially a high one.

Common questions

Does normal calcium mean strong bones?

No. Bone density is measured with a scan, not a blood test.

Should I take calcium if it's low?

Only on a doctor's advice; the cause matters.

Explore further

Sources

  1. MedlinePlus (US National Library of Medicine): Calcium blood test
  2. NIH Office of Dietary Supplements: Calcium fact sheet for health professionals

Free nutrition assessment

Not sure what your body needs?

Answer a few questions about your diet, lifestyle and goals, and SYNC builds a personalised supplement plan with the reason for every suggestion. Free, about 6–8 minutes.

Build My Nutrition Plan

For 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.