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Endgames Case Review

Unexplained metabolic acidosis

BMJ 2021; 375 doi: (Published 24 November 2021) Cite this as: BMJ 2021;375:e067276
  1. James McCaffrey, histopathology registrar,
  2. Kieren Allinson, consultant neuropathologist
  1. Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
  1. Correspondence to: J McCaffrey jm2199{at}

A man in his 20s was found to be unresponsive after experiencing headache and vomiting for two days. His medical history included depression, paracetamol (acetaminophen) overdose on several occasions, and an episode of unexplained encephalopathy five months earlier. He experienced two generalised tonic-clonic seizures during initial assessment in the emergency department. Clinical examination revealed a Glasgow coma scale score of 3/15, with global hypotonia, areflexia, and size 6 pupils that were unresponsive to light.

A systematic ABCDE approach was taken, with a focus on securing the airway because of the patient’s decreased level of consciousness.1

Arterial blood gas test results showed a metabolic acidosis with raised levels of lactate. Table 1 summarises the patient’s laboratory test results on presentation to the emergency department.

View this table:
Table 1

Laboratory test results on presentation to emergency department

The patient was intubated and transferred to the intensive care unit.


1 What laboratory investigations are required for patients with metabolic acidosis?

2 What do the laboratory test results in table 1 show?

3 What are the differential diagnoses in this case?


1 What laboratory investigations are required for patients with metabolic acidosis?

When patients present with metabolic acidosis,123 perform …

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