Etiology

• Most common cause; also referred to as metabolic encephalopathy

• Etiologies include:

  • Liver or kidney failure

  • Diabetes mellitus (diabetic ketoacidosis)

  • Hyperthyroidism or hypothyroidism

  • Vitamin deficiencies (e.g., vitamin B12 deficiency, folic acid deficiency, thiamine deficiency)

  • Electrolyte abnormalities

Infection

• UTIs (most common cause in older patients)

• Pneumonia

• Meningitis

CNS pathology

• Ischemic stroke

• Intracranial hemorrhage

• Brain tumor

Drugs and toxins (toxic encephalopathy)

• Anticholinergics

• Benzodiazepines, barbiturates

• Antidepressants and antipsychotics (especially those with anticholinergic activity, e.g., quetiapine)

• Antihistamines (particularly in older patients)

• Opioids

• Diuretics (may cause electrolyte abnormalities)

• Recreational drugs (intoxication/withdrawal)

• Alcohol use disorder and alcohol withdrawal

• Heavy metals (e.g., arsenic, lead, mercury)

Cardiorespiratory conditions

• Hypoxia (e.g., anemia, pulmonary embolism)

• Hypercapnia (e.g., COPD)

• Acute cardiovascular disease

  • Myocardial infarction

  • Shock

  • Acute heart failure

• Dehydration

Other

• Constipation

• Urinary retention

• Major surgery

• Trauma (e.g., hip fracture, traumatic brain injury)

• Pain

• Sleep deprivation

• Hearing or vision loss

Pediatric, older (> 65 years), and hospitalized patients are particularly susceptible to delirium. [3][4][5]

I WATCH DEATH: Infection, Withdrawal, Acute metabolic disorder, Trauma, CNS pathology, Hypoxia, Deficiencies, Endocrine, Acute vascular, Toxins/drugs, and Heavy metals are the major causes of delirium.