Corrected Calcium Calculator
Corrected Ca = measured + 0.8 × (4 − albumin). Click any i for detail.
Labs (US units)
Measured calcium (mg/dL)
i
Ca
Total calcium from the lab. |
|
|---|---|
Albumin (g/dL)
i
Albumin
Serum albumin. Formula assumes a 4.0 g/dL reference. |
How to use this calculator
- Enter measured total calcium in mg/dL.
- Enter serum albumin in g/dL.
- Read Payne-corrected calcium.
- Prefer ionized calcium when your lab reports it.
Results explained
Low albumin pulls total calcium down without changing ionized calcium. Payne adds 0.8 mg/dL per g/dL albumin below 4.0.
Quick reference: corrected Ca
If albumin is 4.0 g/dL, correction is zero.
| Item | Detail |
|---|---|
| Payne | Ca_corr = Ca + 0.8×(4 − albumin) |
| Albumin 3.2 | adds 0.8×0.8 = 0.64 mg/dL |
| Ionized Ca | preferred when available |
| SI units | convert mmol/L before using this US formula |
pH, citrate, and paraproteins are ignored.
How the estimate is built
Ca_corr = Ca + 0.8 × (4 − albumin).
Example scenario
Ca 8.4, albumin 3.2 → 9.04 mg/dL.
FAQ
Should I treat the corrected number?
This is classroom arithmetic, not treatment advice. Clinicians use context and often ionized Ca.
How do I convert mmol/L?
Total calcium mg/dL ≈ mmol/L × 4 for rough US conversion before Payne.
Does every lab use 4.0 albumin?
Payne assumes 4.0 g/dL reference; some sites use 4.4 variants.