Weakness and palpitations after rapid weight loss for a boxing weigh-in

2026-09-04

The case

22-year-old man. Weakness and palpitations after rapid weight loss for a boxing weigh-in

He has lost 7 kg in twelve days by restricting food and fluids, inducing vomiting and using stimulant laxatives. He takes no prescribed medication and has no known cardiac history.

On arrival

HR: 54
GCS: 15
SpO₂ (%): 99
Respiratory rate: 16
Temperature (°C): 36.5
Systolic BP (mmHg): 98
Diastolic BP (mmHg): 58

Stage 1 of 2

He feels weak but is alert and talking. His pulse is slow with occasional early beats. A twelve-lead is recorded while intravenous access is obtained.

Tracing 1 of 2 for the quiz “Weakness and palpitations after rapid weight loss for a boxing weigh-in”. — Twelve-lead recorded on arrival, 25 mm/s, 10 mm/mV. Open this tracing in the studio

Observations

HR: 54
SpO₂ (%): 99
Respiratory rate: 16
Temperature (°C): 36.5
Systolic BP (mmHg): 98
Diastolic BP (mmHg): 58

Which description best fits this tracing?

AFlattened T waves, ST depression and prominent U waves Correct answer Your answer
BDiffuse ST elevation with PR depression Your answer
CA short QT interval with a normal T-wave contour Your answer
DTall, narrow-based T waves with progressive QRS widening Your answer

Which biochemical abnormality is most strongly suggested by this combination?

ASevere hyperkalaemia Your answer
BIsolated hyponatraemia Your answer
CHypercalcaemia Your answer
DSevere hypokalaemia Correct answer Your answer

Stage 2 of 2

While the first blood sample is being sent, he says he feels faint and then becomes unresponsive. The monitor records this rhythm. No pulse is palpable.

Tracing 2 of 2 for the quiz “Weakness and palpitations after rapid weight loss for a boxing weigh-in”. — Monitor strip recorded at the moment of deterioration, 25 mm/s, 10 mm/mV. Open this tracing in the studio

Bloods

Sodium (mmol/L): 137
Magnesium (mmol/L): 0.54
Potassium (mmol/L): 2.1
Calcium, adjusted (mmol/L): 2.29

What rhythm does the monitor strip show?

AVentricular fibrillation Your answer
BMonomorphic ventricular tachycardia Your answer
CTorsades de pointes Correct answer Your answer
DMovement artifact over sinus rhythm Your answer

What is the immediate action while he remains pulseless in this rhythm?

AGive intravenous magnesium before attempting a shock Your answer
BAttempt synchronised cardioversion Your answer
CGive amiodarone 300 mg before attempting a shock Your answer
DDeliver an unsynchronised defibrillation shock Correct answer Your answer

Diagnosis

Severe hypokalaemia with prominent U waves progressing to torsades de pointes

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<iframe src="https://www.squiggler.io/blog/weakness-and-palpitations-after-rapid-weight-loss-for-a-boxing-weigh-in/embed" title="Weakness and palpitations after rapid weight loss for a boxing weigh-in — ECG case from Squiggler" width="100%" height="900" style="border:0" loading="lazy"></iframe>

This tracing was generated, not recorded. It opens in the studio with every dial live.

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