Calculate the corrected calcium level adjusted for albumin. Enter total serum calcium and albumin to determine the true calcium status when albumin is abnormal.
Normal: 8.5 – 10.5
Normal: 3.5 – 5.0
Corrected Calcium
9.0 mg/dL
Status
Normal
Hypocalcemia: <8.5 | Normal: 8.5–10.5 | Hypercalcemia: >10.5 mg/dL
Albumin Correction Effect
0.0 mg/dLNo correction needed (albumin = 4.0)
Corrected calcium is within normal limits (8.5-10.5 mg/dL). No hypocalcemia or hypercalcemia signs expected.
Calcium is essential for muscle contraction, nerve signaling, blood clotting, and cardiac function. Since a significant portion of circulating calcium is bound to albumin, low albumin levels — common in hospitalized, malnourished, or critically ill patients — can make the total calcium measurement misleading. Correcting for albumin helps clinicians identify true hypocalcemia or hypercalcemia that requires treatment.
About 40% of total serum calcium is bound to albumin. When albumin levels are low (hypoalbuminemia), the measured total calcium will appear falsely low even though the physiologically active ionized calcium may be normal. The correction formula adjusts for this protein binding.
The most commonly used formula is: Corrected Calcium = Measured Total Calcium + 0.8 × (4.0 – Serum Albumin). For each 1 g/dL decrease in albumin below 4.0, the total calcium is adjusted upward by 0.8 mg/dL.
Ionized (free) calcium is the gold standard and should be measured directly when available, especially in critically ill patients, those with acid-base disorders, or patients receiving blood transfusions. The albumin correction formula is an estimate and may be inaccurate in these situations.
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