Calcium
Calcium is essential for bones, muscles, nerves, and heart rhythm. Elevated blood calcium often points to parathyroid issues, vitamin D excess, or rarely cancer.
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What Calcium measures
Total calcium measures both bound and free calcium in blood. Most circulating calcium is bound to albumin, so albumin levels affect interpretation. Ionized calcium (the biologically active form) is more accurate when albumin is abnormal. Most body calcium is stored in bones — blood levels are tightly regulated by parathyroid hormone and vitamin D.
Normal ranges
Reference ranges may vary slightly by lab. Always use the range provided on your specific test report.
What affects your calcium level
- Hyperparathyroidism (most common cause of high calcium)
- Vitamin D excess (over-supplementation)
- Certain cancers (breast, lung, multiple myeloma)
- Kidney disease
- Thiazide diuretics
- Prolonged immobilization
- Magnesium deficiency (causes low calcium)
Foods that may help
Dairy (yogurt, cheese, milk)
Concentrated calcium with cofactor minerals
Sardines and canned salmon (with bones)
Calcium plus vitamin D and omega-3s
Bok choy, kale, collards
Particularly absorbable plant calcium (low oxalate)
Almonds and sesame seeds (tahini)
Concentrated plant calcium
Calcium-set tofu
Excellent vegan calcium source
When to see your doctor
Persistently high calcium needs a parathyroid hormone (PTH) test to identify the cause. Don't supplement calcium without checking with your doctor if you have any kidney or parathyroid concern — calcium supplements can worsen certain conditions.
Related biomarkers
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Educational content only · Not medical advice