In evaluating suspected TCA overdose, which statement is correct?

In evaluating suspected TCA overdose, which statement is correct?

• A. EKG with prolonged QT is useful
• B. Blood glucose elevation confirms overdose
• C. MRI brain is necessary
• D. Lactate levels determine severity

Answer: (A)

In evaluating suspected TCA overdose, the most useful initial test is the ECG because TCAs cause sodium channel blockade that slows cardiac conduction. This effect shows up on the ECG as a prolonged QT interval and other conduction abnormalities; recognizing these changes helps you gauge the severity and risk of dangerous arrhythmias, guiding urgent management such as intravenous sodium bicarbonate and close cardiac monitoring. The QT prolongation itself is a helpful clue to significant drug effect, though in practice the QRS duration is the strongest predictor of toxicity and the key factor guiding treatment decisions. Blood glucose elevation does not confirm overdose and can be incidental; MRI brain isn’t indicated acutely for diagnosing TCA overdose; lactate levels aren’t reliable for determining severity in this context.

In evaluating suspected TCA overdose, the most useful initial test is the ECG because TCAs cause sodium channel blockade that slows cardiac conduction. This effect shows up on the ECG as a prolonged QT interval and other conduction abnormalities; recognizing these changes helps you gauge the severity and risk of dangerous arrhythmias, guiding urgent management such as intravenous sodium bicarbonate and close cardiac monitoring. The QT prolongation itself is a helpful clue to significant drug effect, though in practice the QRS duration is the strongest predictor of toxicity and the key factor guiding treatment decisions.

Blood glucose elevation does not confirm overdose and can be incidental; MRI brain isn’t indicated acutely for diagnosing TCA overdose; lactate levels aren’t reliable for determining severity in this context.