Hydrofluoric acid dermal exposure with systemic hypocalcaemia — MRCEM SBA MCQ

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HardToxicology and environmental emergenciesHydrofluoric acid dermal exposure with systemic hypocalcaemiaMRCEM SBA

A 34-year-old metalworker presents 45 minutes after splashing a concentrated hydrofluoric acid cleaning solution onto his right hand. His glove was removed and the hand irrigated promptly; calcium gluconate gel is being applied, but pain remains severe despite little visible skin damage. He is alert, with a blood pressure of 126/78 mmHg. Continuous cardiac monitoring is in place. His ECG shows sinus rhythm with a QTc of 550 ms, without QRS widening or peaked T waves. Blood tests show ionised calcium 0.72 mmol/L, potassium 6.2 mmol/L, magnesium 0.86 mmol/L and pH 7.36. Which treatment should take priority now?

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Correct answer: A — Administer intravenous calcium gluconate.

This is systemic hydrofluoric acid toxicity, not merely a painful hand burn. Fluoride can penetrate tissue despite limited early skin findings and bind circulating calcium and magnesium. The markedly reduced ionised calcium and prolonged QTc indicate immediately threatening hypocalcaemia. Give intravenous calcium gluconate urgently, maintain cardiac monitoring and continue topical calcium gluconate for the burn. UK chemical-incident guidance specifically prioritises correction of severe hypocalcaemia before treatment of associated hyperkalaemia or acidosis. ([assets.publishing.service.gov.uk](https://assets.publishing.service.gov.uk/media/5b10120c40f0b634d14c21ed/Chemical_biological_radiological_and_nuclear_incidents_clinical_management_and_health_protection.pdf)) **B** is attractive because potassium is 6.2 mmol/L; insulin–glucose may be needed subsequently, but it does not correct the demonstrated hypocalcaemia and is not the first treatment in this presentation. **C** would be relevant for hypomagnesaemia or torsades de pointes; magnesium is normal and no ventricular arrhythmia is present. **D** may be considered with specialist advice for persistent local pain, but local infiltration cannot address systemic hypocalcaemia. **E** may have a role in significant metabolic acidosis, which is absent here, and would not take precedence over calcium. This patient needs ongoing monitored assessment, urgent poisons advice and burns-specialist discussion rather than discharge after local treatment. ([assets.publishing.service.gov.uk](https://assets.publishing.service.gov.uk/media/5b10120c40f0b634d14c21ed/Chemical_biological_radiological_and_nuclear_incidents_clinical_management_and_health_protection.pdf))

Reference: Chemical, biological, radiological and nuclear incidents: clinical management and health protection (May 2018) — https://assets.publishing.service.gov.uk/media/5b10120c40f0b634d14c21ed/Chemical_biological_radiological_and_nuclear_incidents_clinical_management_and_health_protection.pdf Hydrogen Fluoride (HF) and Hydrofluoric Acid: Incident management (September 2024) — https://assets.publishing.service.gov.uk/media/6717bd07d94d2c219a540591/Hydrogen_Fluoride_UKHSA_IM_.pdf