Corrected Calcium Calculator (for Albumin)
Enter total calcium and albumin to get albumin-corrected calcium.
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Corrected Calcium Calculator (for Albumin) by TheCalcTools
How the Corrected Calcium Calculator (for Albumin) works
About 40% of blood calcium is bound to albumin. When albumin is low, total calcium falls even if the active (ionised) calcium is normal. The correction adds 0.8 mg/dL for every 1 g/dL that albumin is below 4.0 (or 0.02 mmol/L per g/L below 40).
The correction is an estimate; measuring ionised calcium directly is more accurate, especially in critical illness.
The formula
Worked example
Using the default values shown in the calculator:
| Units | Calcium mg/dL, albumin g/dL |
|---|---|
| Total calcium | 8.2 |
| Albumin | 2.8 |
- 8.2 + 0.8 × (4.0 − 2.8) = 9.16 mg/dL.
Result:
| Corrected calcium | 9.16 mg/dL |
|---|---|
| In the other unit | 2.29 mmol/L |
| Compared with a typical adult range (8.5 to 10.5 mg/dL) | Within the typical range |
Frequently asked questions
Why do some labs not correct calcium?
Studies show the correction is often inaccurate; many labs recommend ionised calcium instead when it matters.
Sources and further reading
- Payne RB et al. (1973) Interpretation of serum calcium in patients with abnormal serum proteins. BMJ 4:643
- Wikipedia: Hypocalcemia
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This calculator gives general estimates for information and education. It is not medical advice and does not diagnose anything. Talk to a qualified health professional about your own situation. See our disclaimer.