Calculation history
| Date | Measured calcium | Albumin | Corrected calcium | Classification | Laboratory |
|---|---|---|---|---|---|
| No saved calculations yet. | |||||
History stays in this browser. It is not sent to a database. Avoid shared devices when handling identifiable clinical information.
Formula used
The conventional equation adds 0.8 mg/dL per missing albumin g/dL. Its SI counterpart uses 0.02 mmol/L per missing albumin g/L. Laboratories may derive different equations for their own methods.
The tool converts values when either unit selector changes. Custom coefficients remain tied to the displayed units. Check every converted value before submitting the calculation.
How to use this calculator
- Enter measured total calcium from the laboratory report.
- Select the matching calcium unit.
- Enter albumin from the same blood collection.
- Select its matching albumin unit.
- Confirm the reference albumin and formula mode.
- Add your laboratory range when available.
- Calculate, then review the steps and warnings.
Use laboratory-specific ranges whenever they are available. Compare the estimate with symptoms and other investigations. Ask a qualified clinician to interpret concerning results.
Worked example
| Input | Example value |
|---|---|
| Measured calcium | 8.0 mg/dL |
| Albumin | 3.0 g/dL |
| Reference albumin | 4.0 g/dL |
| Coefficient | 0.8 mg/dL per g/dL |
| Estimated corrected calcium | 8.8 mg/dL |
The calculation is 8.0 plus 0.8 times one. This produces an estimated value of 8.8 mg/dL. It remains an estimate, not measured ionised calcium.
Important limitations
Albumin adjustment assumes calcium binding changes predictably with albumin. Illness, pH, kidney function, and assays can disrupt that relationship. Direct ionised calcium may provide a better assessment.
Recent studies report considerable misclassification from common correction equations. Risk increases when albumin is low or kidney function declines. Never use this estimate as a standalone diagnosis.
Frequently asked questions
What does corrected calcium estimate?
It estimates total calcium at a chosen reference albumin. The calculation adjusts for albumin-bound calcium mathematically. It does not directly measure active ionised calcium.
Which formula does the calculator use?
The default uses the common simplified albumin equation. Equivalent coefficients change with the selected units. You can enter a laboratory-specific coefficient instead.
Why must calcium and albumin come together?
Values from different collections may reflect different physiology. Timing differences can weaken the estimate further. Use results drawn during the same collection whenever possible.
Can I use mmol/L and g/dL together?
Yes, the calculator supports mixed unit combinations. It selects the matching simplified coefficient automatically. Confirm displayed values after every unit change carefully.
Why is there no fixed normal range?
Reference intervals vary between laboratories and patient groups. Methods and populations can change the reported limits. Enter the range printed on your laboratory report.
Should correction occur above normal albumin?
Practices differ when albumin exceeds the chosen target. The checkbox can prevent a downward adjustment. Follow the method specified by your laboratory locally.
Is corrected calcium reliable in kidney disease?
Reliability can decrease when kidney function is impaired. Protein binding and related physiology may differ substantially. Clinicians may prefer directly measured ionised calcium instead.
Can this diagnose hypocalcaemia or hypercalcaemia?
No, the calculator provides an educational estimate only. Diagnosis needs clinical assessment and appropriate laboratory testing. Urgent symptoms require prompt professional medical assessment.
What does the paediatric mode change?
It adds reminders about age-dependent reference intervals. The mathematical equation itself remains user-selected. Use paediatric laboratory guidance for every child assessed.
Where is calculation history stored?
History is stored locally inside your web browser. The PHP page does not create patient records. Clear browser history before leaving any shared device.
When is ionised calcium preferred?
It may be preferred when accurate calcium status matters. Critical illness and abnormal protein states increase uncertainty. A clinician should choose the appropriate laboratory test.
Clinical references and disclaimer
This page implements a widely used historical equation. Evidence increasingly questions routine albumin-adjusted calcium reporting. Review current local guidance before clinical implementation.
- 2026 international position statement on albumin-adjusted calcium
- 2025 study comparing adjusted calcium with ionised calcium
- Formula background and ionised calcium discussion
Medical disclaimer: This calculator supports education and documentation only. It cannot diagnose, treat, or replace professional judgement. Seek qualified care for abnormal results or symptoms.