Which EKG abnormality is listed as associated with lithium therapy?

• A. Inverted T-waves
• B. Hyperkalemia
• C. Hypercalcemia
• D. Hyperglycemia

Answer: (A)

Lithium can affect the heart's electrical activity, and T-wave changes are one of the EKG abnormalities that have been described with its use. Inverted T waves reflect alterations in ventricular repolarization that can occur with certain medications, including lithium, even when levels are within the therapeutic range. Among the options, inverted T waves best fit a lithium-associated EKG finding because the other metabolic abnormalities—hyperkalemia (which produces peaked T waves and other conduction changes), hypercalcemia (which tends to shorten the QT interval), and hyperglycemia (which does not have a specific, characteristic EKG pattern)—do not describe lithium’s typical EKG effect. If T-wave inversion is observed in a patient on lithium, assess for possible toxicity, review electrolytes and renal function, and consider checking lithium levels and adjusting the dose as needed. Baseline and periodic EKG monitoring may be prudent, especially in patients with preexisting cardiac disease or electrolyte imbalances.