Hyper-/Hypocalcemia can cause ECG changes secondary to altered trans-membrane potentials that affect conduction times. (Sources 1,2). Hypercalcemia: The most common ECG findings of hypercalcemia are a short QT interval (Ref. 1) secondary to a shortened ST segment. (Source 3) There may also be a widened or flattened T wave; however, significant hypercalcemia can cause ECG changes that mimic an acute myocardial infarction. (Ref. 2,3) Hypercalcemia has also been known to cause an ECG finding mimicking hypothermia, known as an Osborn wave. (Ref. 4) Hypocalcemia: The most significant sign is intermittent QT prolongation, or intermittent prolongation of the QTc (corrected QT interval) secondary to a lengthened ST segment. Although rare, this may lead to arrhythmias such as torsades de pointes, VT, or complete heart block. (Source 3).
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