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Pioglitazone heart failure — GPhC CRA MCQ

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HardEndocrine TherapeuticsPioglitazone heart failureGPhC CRA

A stable patient taking digoxin 125 micrograms each morning has a routine serum concentration reported as 2.4 nanograms/mL. The sample was taken two hours after today's dose. They have no nausea, visual change or arrhythmia; potassium, magnesium and renal function are unchanged. What is the best interpretation and next step?

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Correct answer: C — Interpret clinically and repeat, if needed, at least six hours after a dose

A concentration taken only two hours after oral digoxin reflects the distribution phase and can be misleadingly high. SPS advises sampling no less than six hours, ideally eight to twelve hours, after the last dose. Toxicity is a clinical diagnosis informed by symptoms, ECG, renal function and potassium, magnesium and calcium; it can occur within the quoted range and may be absent above it. This asymptomatic result should not trigger permanent withdrawal or dose escalation. Routine weekly levels are not recommended in a stable patient, but a correctly timed repeat can clarify this anomalous result.

Reference: NHS SPS: Digoxin monitoring. https://www.sps.nhs.uk/monitorings/digoxin-monitoring/