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Hypophosphataemia Cardiac Complications — FRCA Final MCQ

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ModerateIntensive Care MedicineHypophosphataemia Cardiac ComplicationsFRCA Final

A 50-year-old man (ASA II) on ICU is receiving enteral nutrition at target rate. His phosphate drops to 0.3 mmol/L. He is at risk of refeeding syndrome. What is the most dangerous cardiac complication of severe hypophosphataemia?

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Correct answer: B — Cardiac failure and arrhythmias from impaired myocardial contractility due to ATP depletion

Severe hypophosphataemia (<0.3 mmol/L) depletes intracellular ATP and 2,3-DPG, causing: impaired myocardial contractility (cardiac failure), skeletal muscle weakness (including respiratory muscles – difficulty weaning from ventilation), arrhythmias, rhabdomyolysis, haemolytic anaemia (RBC ATP depletion), and neurological dysfunction (confusion, seizures, coma). Phosphate is driven intracellularly by insulin release when carbohydrate feeding is commenced in malnourished patients (refeeding syndrome). Treatment: IV sodium or potassium phosphate replacement with cardiac monitoring.

Reference: NICE – 2017 – CG32 Nutrition support; ESPEN – 2019 – ICU nutrition guidelines