Corrected Calcium Calculator
Calculate corrected calcium levels for patients with abnormal albumin concentrations
Calculate Corrected Calcium
Medical Professional Use
This calculator is for healthcare professionals to assess calcium levels in patients with abnormal albumin. Clinical correlation and additional testing may be required for proper interpretation.
Select patient type for appropriate reference ranges
Normal: 8.8-10.5 mg/dL
Normal: 3.5-5.5 g/dL
Typically 4.0 g/dL (laboratory standard)
Corrected Calcium Results
Enter values to calculate corrected calcium
Calcium Correction Formula
Clinical Context
Example Calculation
Clinical Scenario
Patient: Adult with hypoalbuminemia
Serum Ca: 7.2 mg/dL (low)
Albumin: 1.1 g/dL (very low)
Question: True hypocalcemia?
Calculation
Corrected Ca = (0.8 x (4.0 - 1.1)) + 7.2
Corrected Ca = (0.8 x 2.9) + 7.2
Corrected Ca = 2.32 + 7.2
Corrected Ca = 9.52 mg/dL (Normal!)
Normal Ranges
Serum Calcium
8.8-10.5 mg/dL
(2.25-2.625 mmol/L)
Serum Albumin
3.5-5.5 g/dL
(35-55 g/L)
When to Use
Understanding Corrected Calcium
Why Correct for Albumin?
About 40% of serum calcium is bound to albumin, making measured calcium levels dependent on albumin concentration. In patients with hypoalbuminemia, measured calcium may appear falsely low even when ionized (biologically active) calcium is normal. Corrected calcium provides a more accurate assessment of true calcium status.
Clinical Applications
- •Assess true calcium status in hypoalbuminemia
- •Guide calcium replacement therapy decisions
- •Evaluate hypercalcemia in critical illness
- •Monitor calcium in pregnancy and malnutrition
Correction Formula
Corrected Ca = (0.8 × (4.0 - Albumin)) + Serum Ca
Where:
- 0.8 = Correction factor (mg/dL)
- 4.0 = Normal albumin reference (g/dL)
- Albumin = Patient's serum albumin (g/dL)
- Serum Ca = Measured serum calcium (mg/dL)
Important Limitation: This formula is not valid for patients with chronic kidney disease or end-stage renal disease, where different correction factors may apply.
Calcium Distribution in Serum
Ionized Calcium (45%)
Biologically Active Form
• Participates in physiological processes
• Regulates muscle contraction
• Controls nerve function
Protein-Bound (40%)
Albumin-Bound Fraction
• Not biologically active
• Varies with albumin levels
• Requires correction for accurate assessment
Complexed (15%)
Bound to Anions
• Citrate, phosphate, bicarbonate
• Relatively stable fraction
• Not significantly affected by albumin
Hypocalcemia vs. Hypercalcemia
Hypocalcemia (<8.8 mg/dL)
Symptoms:
- Tetany, muscle spasms
- Chvostek and Trousseau signs
- QT prolongation
- Seizures (severe cases)
Common Causes:
- Hypoparathyroidism
- Vitamin D deficiency
- Chronic kidney disease
- Pancreatitis
Hypercalcemia (>10.5 mg/dL)
Symptoms:
- Fatigue, confusion
- Kidney stones
- Bone pain
- Cardiac arrhythmias
Common Causes:
- Primary hyperparathyroidism
- Malignancy
- Granulomatous diseases
- Vitamin D intoxication