What are the electrocardiogram (EKG) findings in hypercalcemia?

From the Guidelines

Hypercalcemia typically causes characteristic EKG changes including a shortened QT interval, which is the most consistent finding. On an EKG, you may observe a QT interval that is shorter than expected for the heart rate. Other findings can include flattened or absent T waves, widened T waves that may merge with the P wave of the next beat (creating what appears to be a prolonged PR interval), and occasionally ST segment changes. In severe cases, you might see bradyarrhythmias or heart blocks. The shortened QT interval occurs because hypercalcemia accelerates cardiac repolarization, specifically shortening the plateau phase (phase 2) of the cardiac action potential. This happens because excess calcium ions affect the function of calcium and potassium channels in cardiac myocytes. When interpreting an EKG with suspected hypercalcemia, it's essential to calculate the corrected QT interval (QTc) to account for heart rate variations. A QTc less than 350 ms should raise suspicion for hypercalcemia, especially when accompanied by other clinical signs such as confusion, constipation, abdominal pain, or a history of conditions associated with high calcium levels like hyperparathyroidism or malignancy 1.

Some key points to consider when evaluating EKG changes in hypercalcemia include:

• The EKG is a crucial tool for diagnosing and monitoring cardiac conditions, including those related to electrolyte imbalances like hypercalcemia 1.
• The interpretation of EKG findings should always be done in the context of the patient's clinical presentation and other diagnostic tests 1.
• Hypercalcemia can lead to various EKG changes, but a shortened QT interval is the most consistent finding, and it is essential to calculate the corrected QT interval (QTc) to account for heart rate variations 1.

It is also important to note that while the provided studies primarily discuss hyperkalemia, the question is about hypercalcemia, and the relevant information from the studies is limited. However, based on the available evidence and general medical knowledge, the most critical aspect of EKG interpretation in hypercalcemia is recognizing the shortened QT interval and considering it in the context of the patient's overall clinical presentation. This approach allows for the early identification and management of hypercalcemia, which is crucial for preventing morbidity and mortality associated with this condition.

From the Research

EKG Changes in Hypercalcemia

• Characteristic EKG changes in hypercalcemia include:
  • Shortening of the QT interval 2
  • Shortening of the QoT, QaT, and QeT intervals 3
  • Prolongation of the PR and QRS intervals at very high serum calcium levels 3
  • T wave flattening or inversion 3
  • Appearance of a J wave at the end of the QRS complex 3
• Hypercalcemia can also cause ST elevation, mimicking acute myocardial infarction 3
• However, the Q-T interval is not a useful clue to the presence of hypercalcemia, as it is often not shortened even in patients with severe hypercalcemia 2

Clinical Presentation

• Hypercalcemia can present with various symptoms, including seizures, altered sensorium, and acute severe pancreatitis 4
• It can also be caused by primary hyperparathyroidism, malignancy, and other conditions 4, 5, 6
• Denosumab has been shown to be effective in treating hypercalcemia in patients with primary hyperparathyroidism and malignancy 4, 5, 6

Diagnosis and Treatment

• Diagnosis of hypercalcemia is typically made through laboratory testing, including serum calcium levels 4, 5, 6, 2, 3
• Treatment of hypercalcemia depends on the underlying cause and severity of the condition, and may include volume resuscitation, parenteral salmon calcitonin, and administration of intravenous bisphosphonates or denosumab 4, 5, 6