Which investigations should be prioritized in a patient presenting with acute confusion to rule out underlying causes of delirium?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 16 August 2025Updated: 16 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX
In a patient presenting with acute confusion, the primary objective is to identify and manage the possible underlying cause or combination of causes of delirium . An initial assessment should be conducted using an appropriate tool, such as the 4AT . Prioritized investigations should focus on common reversible causes, including:
  • A comprehensive medication review, taking into account both the type and number of medications, and considering cognitive impairment from medicines associated with increased anticholinergic burden ,,.
  • Addressing poor nutrition .
  • Resolving sensory impairments, such as impacted ear wax, and ensuring hearing and visual aids are available and in good working order ,,.
  • Assessing for intercurrent illnesses, such as urinary tract infections or faecal impaction .
  • Checking for dehydration .
  • Evaluating for pain .
  • Considering structural imaging to rule out reversible causes of cognitive decline and to assist with subtype diagnosis, unless dementia is well established and the subtype is clear .
If there is difficulty distinguishing between delirium, dementia, or delirium superimposed on dementia, the delirium should be managed first ,. If further investigations not available in primary care are needed, or if the person does not respond to initial treatment, admission to hospital or seeking advice from an elderly care consultant or psychiatrist should be considered .

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