← All Biomarkers

Calcium (serum)

Mineral Unit: mg/dL

Bone health and neuromuscular function

Also known as: Ca,Serum Calcium

Reference Ranges

Clinical Reference 8.5 – 10.5 mg/dL

Optimal Range 9.0 – 10.0 mg/dL

Critical Range < 6.5 / > 13.0 mg/dL

Corrected for albumin; ionized Ca more accurate

Related Conditions

Osteoporosis Low

Food & Lifestyle Recommendations

🍎 Food Include dairy, sardines with bones, kale, and fortified plant milk; spread intake across meals The body absorbs calcium best in doses of 500mg or less

Evidence-Backed Supplements

When Low

Calcium Tier A May Increase

Direct supplementation; combine with vitamin D

Calcium citrate or carbonate 500–600 mg 2x/day With meals (carbonate) or anytime (citrate)

PMID 30132304 PMID 39560075 PMID 25922862
Vitamin D Tier A Supports Normalization

Required for calcium absorption

Vitamin D3 (cholecalciferol) 2000–5000 IU/day Morning

PMID 19370554 PMID 24414552 PMID 24729336

Questions to Ask Your Doctor

Should my calcium be corrected for albumin, and should I also check ionized calcium? Ionized Ca is the biologically active form

Upload your blood test to see how your Calcium (serum) compares to reference and optimal ranges.

Upload Blood Test