Calcium Level

Always relate serum calcium levels to serum albumin levels [5].

Method for calculating correction of calcium level to reflect albumin level:

• If serum albumin is less than 40 g/L, increase measured calcium by 0.20 mmol/L for every 10 g of albumin below 40 g/L
• If serum albumin is greater than 40 g/L, reduce measured calcium by 0.20 mmol/L for every 10 g of albumin over 40 g/L

Alternatively:

• Corrected calcium (mmol/L) = Measured calcium (mmol/L) + [0.02 x (40 – measured albumin g/L)]

Hypercalcaemia may produce ECG abnormalities related to altered trans-membrane potentials that affect conduction time. QT interval shortening is common and, in some cases, the PR interval is prolonged. At very high levels, the QRS interval may lengthen, T waves may flatten or invert, and a variable degree of heart block may develop. Digoxin effects are amplified.