Delirium (acute confusion, especially in older people)

In the practice, straight away

• Capillary blood glucose, temperature, oxygen saturation, blood pressure, ECG; look for urinary retention, faecal impaction, unexpressed pain
• Urine dipstick (leucocytes, nitrites)

Laboratory tests (without delay, non-fasting)

• FBC
• CRP
• Serum electrolytes (sodium, potassium)
• Urea
• Serum creatinine with eGFR
• Serum calcium
• Total serum protein
• Venous plasma glucose
• Urine microscopy and culture (only if urinary signs or fever)if neededUrinary signs or fever with a positive dipstick. Bacteriuria with isolated confusion in a patient over 75 or frail may reflect a urinary tract infection, but other causes must be ruled out first ^[2].
• TSH (depending on the context)if neededTargeted test, to be considered according to the history and clinical examination (signs of thyroid dysfunction), not part of the routine HAS tests ^[1,3].
• Vitamin B12 (depending on the context)if neededTargeted test, to be considered according to the history and clinical examination (undernutrition, underlying cognitive impairment), not part of the routine HAS tests ^[1,3].
• Folate (if malnutrition or macrocytosis)if needednon-French guidelineThe Scottish guideline (SIGN 157, 2019) suggests measuring vitamin B12 and folate if nutritional status is in doubt or if there is macrocytosis on the FBC ^[4]. The HAS recommendation does not cite folate ^[3].
• ASTif needednon-French guidelineAlcohol consumption, known liver disease or signs of liver failure: liver function tests are among the targeted tests according to the history and examination ^[1].
• ALTif needednon-French guidelineAlcohol consumption, known liver disease or signs of liver failure: liver function tests are among the targeted tests according to the history and examination ^[1].
• GGTif needednon-French guidelineAlcohol consumption, known liver disease or signs of liver failure: liver function tests are among the targeted tests according to the history and examination ^[1].
• Bilirubinif needednon-French guidelineAlcohol consumption, known liver disease or signs of liver failure: liver function tests are among the targeted tests according to the history and examination ^[1].
• Serum lithium (if on lithium)if neededPatient treated with lithium: measurement of the drug taken by the patient, to be considered according to the history ^[1]. State the time of the last dose and the dosage ^[5].
• Serum digoxin (if on digoxin)if neededPatient treated with digoxin, a drug cited among the causes of acute confusion ^[3]; especially if renal function has deteriorated. State the time of the last dose and the dosage ^[5].
• Valproic acid (if on treatment)if neededPatient treated with valproate: antiepileptics are among the causes of acute confusion ^[3]; measurement to be considered according to the history ^[1].
• Carbamazepine (if on treatment)if neededPatient treated with carbamazepine: antiepileptics are among the causes of acute confusion ^[3]; measurement to be considered according to the history ^[1].
• Phenytoin (if on treatment)if neededPatient treated with phenytoin: antiepileptics are among the causes of acute confusion ^[3]; measurement to be considered according to the history ^[1].
• Phenobarbital (if on treatment)if neededPatient treated with phenobarbital: antiepileptics are among the causes of acute confusion ^[3]; measurement to be considered according to the history ^[1].