Corrected Calcium Calculator
Calculate corrected calcium adjusted for albumin level. Uses the standard calcium correction formula for hypoalbuminemia with clinical interpretation.
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Über dieses Tool
What Is Corrected Calcium?
Approximately 40% of total serum calcium is bound to albumin. In hypoalbuminemic states (common in hospitalized patients, cirrhosis, nephrotic syndrome, malnutrition), total calcium appears artificially low even when the physiologically active ionized fraction is normal. The corrected calcium formula adjusts for this: Corrected Ca = Measured Ca + 0.8 × (4.0 − albumin). This provides a rough estimate of what the total calcium would be if albumin were normal.
When to Use Corrected Calcium
Calculate corrected calcium whenever the total serum calcium is interpreted in a patient with abnormal albumin levels — particularly when albumin is <3.5 g/dL. This is relevant for evaluating hypocalcemia, hypercalcemia, and monitoring calcium in perioperative patients, ICU patients, and those with liver or kidney disease. When precision matters (e.g., symptomatic hypocalcemia, hyperparathyroidism workup), measure ionized calcium directly.
Interpreting Corrected Calcium Results
Normal total calcium range is approximately 8.5–10.5 mg/dL (2.12–2.62 mmol/L). After albumin correction, values below 8.5 mg/dL suggest true hypocalcemia, and values above 10.5 suggest true hypercalcemia. However, the correction formula is imprecise — accuracy diminishes in critically ill patients, those with acid-base disturbances, and in extreme hypoalbuminemia.
🔑 Klinische Hinweise
- The correction formula (Payne's formula) was derived in a small cohort in 1973 and has well-documented limitations. When clinical decisions depend on calcium levels, measure ionized calcium directly.
- Acidosis increases ionized calcium (H⁺ displaces Ca²⁺ from albumin), while alkalosis decreases it. The correction formula does not account for pH.
- Common causes of true hypocalcemia: vitamin D deficiency, hypoparathyroidism, CKD, pancreatitis, massive transfusion (citrate). Common causes of hypercalcemia: primary hyperparathyroidism, malignancy.
- In critical illness, both albumin and calcium binding are altered — corrected calcium formulas are least reliable when you need them most. Ionized calcium is the gold standard.
Schlüsselreferenzen
- Payne RB, et al. Interpretation of serum calcium in patients with abnormal serum proteins. BMJ. 1973;4(5893):643–646.
- Byrnes MC, Huynh K, Helmer SD, et al. A comparison of corrected serum calcium levels to ionized calcium levels among critically ill surgical patients. Am J Surg. 2005;189(3):310–314.
- Bushinsky DA, Monk RD. Electrolyte quintet: Calcium. Lancet. 1998;352(9124):306–311.
Formel zuletzt überprüft: Februar 2026