Delirium may be<unk>  by severe physical or mental illness, or any process which interferes with the normal metabolism or function of the brain such as fever, pain, poison (toxic drug reactions), brain injury, surgery, traumatic shock, severe lack of food or water or sleep, and even withdrawal symptoms of certain drug and alcohol dependent states.  In addition, there is an interaction between acute and chronic symptoms of brain dysfunction. Delirious states are more easily produced in people already suffering from underlying chronic brain dysfunction. A very common<unk> of delirium  in elderly people is a urinary tract infection, which is easily treatable with antibiotics.
Delirium, like mental confusion, is a very general and nonspecific symptom of organ dysfunction. In addition to many organic<unk>  relating to a structural defect or a metabolic problem in the brain, there are also some psychiatric<unk> , which may also include a component of mental or emotional stress, mental disease.
Life-threatening<unk>  include conditions that may result in death or permanent disability within 24 hours if left untreated.
Acute liver failure
Acute Metabolic (acidosis, alkalosis, renal failure, electrolyte imbalances)
Acute vascular disorder  (Stroke, MI, pulmonary embolism, heart failure)
Adrenal cortex insufficiency
Acute Altitude sickness
Brain infection
Decompression sickness
Gangrene
Head injury
Hyperosmolar non-ketotic diabetic coma
Hyperthermia
Hypoglycemia
Hypothermia
Hypoxia
Hypoxemia
Raised intracranial pressure
Rickettsiae
Sepsis
Toxins/drugs
Withdrawal
Antiarrhythmic
Antihistamine
Antiparkinsonian  drugs such as benzatropine
Antispasmodic
Benzodiazepine
Diuretic e.g. Furosemide
Incontinence medicines e.g. Oxybutynin
Opioid Analgesics
Tricyclic antidepressant.
Infections (Pneumonia, Urinary Tract Infections)
Recreational drug use,Drugs popularly used for recreation|Withdrawal]] (ethanol, opiate)
Acute Metabolic disroder (acidosis, alkalosis, renal failure, electrolyte imbalances)
Trauma (acute severe pain)
Central nervous system pathology (epilepsy, cerebral hemorrhage)
Hypoxia
Vitamin Deficiencies (vitamin B12, thiamine)
Endocriopathies
Acute vascular disease (Stroke, MI, pulmonary embolism, heart failure)
Heavy metals
Recreational drug use
Hypermagnesemia, Hypercalcemia, Hypomagnesemia, Hyperphosphatemia, Chronic renal failure, Acute renal failure
Acute altitude sickness
Acute intermittent porphyria
Acute liver failure
Acute renal failure
Adrenal cortex insufficiency
Alcohol withdrawal
Antihistamines
Antipsychotics
Brain abscess
Brain infection
Brain or epidural abscess
Brain tumor
Burns
Cabergoline
Carbon monoxide toxicity
Carbon tetrachloride
Cardiac failure
Cerebral infarction
Cerebral malaria
Cerebral oedema
Cerebrovascular accident
Chest infection
Chronic Liver failure
Chronic renal failure
Coproporphyria, hereditary
Cushing syndrome
Cyanide
Daphne poisoning 
Decompression sickness
Diabetic hypoglycemia
Diabetic ketoacidosis
Drug overdose
Drug withdrawal
Electric shock
Elevated or depressed adrenal function
Elevated or depressed pancreas function
Elevated or depressed pituitary function
Encephalitis
Encephalitis
Epidural haemorrhage
Epileptic seizures
Ethanol
Ethylene glycol
Fat embolism
Folate  deficiency
Gangrene 
Hallucinogens
Head injury
Heart failure
Heat stroke
Heroin
Hperthyroidism
Hpherphosphatemia
Hydrogen sulfide
Hyomagnesemia
Hyperbaric sickness
Hypercalcemia
Hypercarbia
Hypereosinophilia
Hyperglycemia
Hypermagnesia
Hypernatremia
Hyperosmolar non-ketotic diabetic coma
Hyperosmolar states
Hypertensive encephalopathy
Hyperthermia
Hyperthyroid
Hypocalcemia
Hypoglycemia
Hyponatremia
hypoosmolar states
Hypophosphatemia
Hypopituitarism
Hypothermia
Hypothyroidism
Hypoxemia
Hypoxia
Infections
Intracranial abscess / granuloma
Intracranial bleeding
Intraspinal abscess / granuloma
Jimson weed
Lead
Leukemic blast cell crisis
Lithium
Liver failure
Malaria
Malignant hypertension
Marijuana
Meningitis
Meningoencephalitis
Methanol
Monomethylhydrazine
Muscle relaxant
Neurocysticercosis
Niacin deficiencies
Nickel poisoning
Nonconvulsive status epilepticus
Organic solvent
Phaeochromocytoma
Phencyclidine
Pituitary apoplexy
Plague
Poison hemlock
Polycythemia
Porphyria
Postictal state
Postoperative stress
Pyelonephritis
Quinolones
Rabies
Raised intracranial pressure
Renal failure, acute
Renal failure, chronic
Respiratory failure
Rickettsiae
Schizoaffective disorder
Sepsis
Serotonin syndrome
Skull fracture
Sleeping sickness (East African)
Sleeping sickness (West African)
Subdural empyema
Surgical wound infection
Systemic infection
systemic inflammatory response syndrome
Systemic organ failure
Texas Mescalbean poisoning
Thallium Sulfate poisoning
Thiamine (Vitamin B1) deficiency
Thrombocytosis
Toluene
Trauma
Typhoid fever
Urinary tract infection
Valproic acid
Vancomycin resistant enterococcal bacteremia
Vasculitis
Venous sinus thrombosis
Viral hemorrhagic fever
Vitamin B12 deficiency
Water hemlock poisoning
Wernicke's encephalopathy
Wilson's disease
Withdrawal states e.g. ethanol, benzodiazepines
Zanamivir
Delirium causes
Schizophrenia causes
Personality disorder causes
Amnesia causes
Dementia causes
Delirium risk factors
Altered mental status pathophysiology
Tremor causes