An Osborn or J wave on EKG is most commonly associated with which condition?

• A. Hyperkalemia
• B. Ischemia
• C. Hypothyroidism
• D. Hypothermia

Answer: (D)

Osborn (J) waves are a classic finding in hypothermia. When body temperature drops, the epicardial and endocardial layers repolarize at different rates, creating a prominent notch at the J point that appears as an upward deflection—the Osborn wave. This ECG sign signals cold-induced changes in myocardial electrophysiology and is associated with an increased risk of ventricular arrhythmias, so the clinical focus is on rewarming and treating the hypothermia. In contrast, hyperkalemia typically produces tall, peaked T waves and QRS widening; ischemia shows ST-segment elevations or depressions and possible new Q waves; hypothyroidism tends to cause bradycardia and low voltage rather than distinct J waves.