Interpretation
| Result | Meaning |
|---|---|
| < 8.5 mg/dL (< 2.12 mmol/L) | Hypocalcaemia |
| 8.5–10.5 mg/dL (2.12–2.62 mmol/L) | Normal |
| 10.6–11.9 mg/dL | Mild hypercalcaemia |
| ≥ 12 mg/dL (≥ 3.0 mmol/L) | Moderate–severe hypercalcaemia |
Formula
Corrected Ca (mg/dL) = Ca + 0.8 × (4.0 − albumin g/dL). SI: Corrected Ca (mmol/L) = Ca + 0.02 × (40 − albumin g/L).
Clinical pearls
- Albumin correction is unreliable in critical illness, CKD and with abnormal pH; measure ionised calcium instead.
- Some labs use a locally derived correction formula and reference albumin; follow your lab if it reports adjusted calcium.
Examples
corrected calcium 8.0 albumin 2.5corrected ca 2.05 mmol/L alb 24 g/Lwhat is the true calcium if calcium is 7.8 and albumin is 2.0
FAQ
How do you correct calcium for low albumin?
Add 0.8 mg/dL to the measured calcium for every 1 g/dL that albumin is below 4.0 (or 0.02 mmol/L per g/L below 40 g/L).
When should I order ionised calcium instead?
In critically ill patients, advanced CKD, acid–base disturbances, or whenever the corrected value would change management.