Which of the following is a non-cardiac cause of palpitations?

- Hypoglycemia is a non-cardiac cause of palpitations caused by the activation of the sympathetic nervous system in response to low blood glucose.
- This leads to the release of adrenaline, resulting in symptoms like palpitations, sweating, and tremors without intrinsic cardiac pathology.
- In contrast, atrial fibrillation and mitral valve prolapse are primary cardiac causes, while hyperthyroidism affects the cardiovascular system directly by increasing heart rate and contractility.
- Thus, hypoglycemia-induced palpitations stem from an extragenic metabolic disturbance, not a cardiac abnormality.

Reference: Davidson’s Principles and Practice of Medicine, 24th Edition, Chapter: Cardiovascular disease, Page 565.