Corrected Calcium Calculator
Medical calculator that adjusts serum calcium levels based on albumin concentration using Payne’s formula. Essential for accurate diagnosis of calcium disorders in patients with abnormal albumin levels.
What Is It?
The Corrected Calcium Calculator is a clinical tool that applies Payne’s formula (Corrected Ca = Serum Ca + 0.8 × (4 - Albumin)) to account for variations in serum albumin levels. This adjustment is crucial because approximately 50% of serum calcium is protein-bound, primarily to albumin.
How to Use
- Enter Serum Calcium: Input measured total calcium level (8.5-10.2 mg/dL normal range)
- Provide Albumin Level: Current serum albumin concentration (3.5-5.0 g/dL normal range)
- Calculate: Automatic computation using the formula
- Interpret Results:
- Hypocalcemia: <8.5 mg/dL
- Normal: 8.5-10.2 mg/dL
- Hypercalcemia: >10.2 mg/dL
Key Terminology
- Payne’s Formula: Standard equation for calcium correction
- Ionized Calcium: Physiologically active form (not measured here)
- Hypoalbuminemia: Low serum albumin (<3.5 g/dL)
- Parathyroid Hormone (PTH): Key calcium regulator
- Vitamin D: Essential for calcium absorption
Clinical FAQs
Q: When is correction necessary?
A: When albumin levels are <4.0 g/dL or >5.0 g/dL.
Q: How often should corrected calcium be calculated?
A: With every electrolyte panel showing abnormal albumin.
Q: Does this replace ionized calcium testing?
A: No - direct measurement is preferred in critical cases.
Q: Why 0.8 multiplier in the formula?
A: Represents the binding coefficient of calcium to albumin.
Interpretation Guide
| Corrected Calcium | Clinical Significance |
|---|---|
| <7.5 mg/dL | Severe hypocalcemia |
| 7.5-8.4 mg/dL | Mild hypocalcemia |
| 8.5-10.2 mg/dL | Normal range |
| 10.3-11.9 mg/dL | Mild hypercalcemia |
| ≥12.0 mg/dL | Severe hypercalcemia |
Special Considerations
- Not valid for pediatric patients
- Margin of error: ±0.2 mg/dL
- Always correlate with clinical symptoms
- Verify abnormal results with repeat testing