Hallucinations (young adult, older person): look for an organic cause

Fasting laboratory tests

• FBC
• CRP
• Serum electrolytes
• Serum calcium
• Serum creatinine with eGFR
• AST
• ALT
• GGT
• Fasting plasma glucose
• TSH
• Syphilis serology
• HIV serology (with the patient's consent)
• Hepatitis C serology (if risk factor)if neededRisk factor for HCV exposure: the C'JAAD booklet proposes it only in this case ^[2].
• Hepatitis B serology (if risk factor)if needednon-French guidelineRisk factor for HBV exposure: the Australian and New Zealand recommendation places hepatitis screening in the initial tests ^[3] and the German S3 recommendation among the tests guided by warning signs ^[4]. The French C'JAAD booklet cites only HCV serology ^[2].
• Vitamin B12if neededProposed routinely by the C'JAAD booklet (summary of the Australian recommendations) ^[2], but absent from the initial tests retained by the Dissaux review ^[5].
• Folateif neededProposed routinely by the C'JAAD booklet (summary of the Australian recommendations) ^[2], but absent from the initial tests retained by the Dissaux review ^[5].
• Antinuclear antibodies (ANA)if neededLooking for lupus or an autoimmune disease: proposed in the initial tests by the C'JAAD booklet and by the Dissaux review ^[2,5], to be discussed with the psychiatrist conducting the work-up.
• Serum copper and caeruloplasmin (Wilson disease)if neededLooking for Wilson's disease: proposed in the initial tests by the C'JAAD booklet (copper and caeruloplasmin) and by the Dissaux review (caeruloplasmin) ^[2,5].
• β-hCG (woman of childbearing potential)if neededWoman of childbearing potential, before any treatment: the C'JAAD booklet places it in the routine tests ^[2].
• CK (if catatonia, rigidity or fever)if needednon-French guidelineThe German S3 recommendation lists it among the optional tests, in the presence of signs pointing to a somatic cause, and counts a CK at least 4 times normal among the criteria for neuroleptic malignant syndrome ^[4]. The French C'JAAD booklet does not cite it ^[2].

Urine tests

• Urine drug screen (cannabis, cocaine, amphetamines, opiates)

Laboratory tests (non-fasting)

• FBC
• CRP
• Serum electrolytes
• Serum creatinine with eGFR
• Serum calcium
• Total serum protein
• Plasma glucose
• TSH (depending on the context)if needednon-French guidelineTargeted test according to the history and examination, as part of the work-up for confusion or cognitive disorders ^[9].
• Vitamin B12 (depending on the context)if needednon-French guidelineTargeted test according to the history and examination, as part of the work-up for confusion or cognitive disorders ^[9].
• Folate (if malnutrition or macrocytosis)if needednon-French guidelineThe Scottish SIGN 157 recommendation proposes vitamin B12 and folate if nutritional status is in doubt or in case of macrocytosis ^[10]. The initial tests of the HAS (2009) do not mention them ^[11].
• ASTif needednon-French guidelineThe Scottish SIGN 157 recommendation counts liver function tests among the usual tests for confusion, and an American Family Physician review among those to consider when the diagnosis is unclear ^[10,12]. The initial tests of the HAS (2009) do not mention them ^[11].
• ALTif needednon-French guidelineThe Scottish SIGN 157 recommendation counts liver function tests among the usual tests for confusion, and an American Family Physician review among those to consider when the diagnosis is unclear ^[10,12]. The initial tests of the HAS (2009) do not mention them ^[11].
• GGTif needednon-French guidelineThe Scottish SIGN 157 recommendation counts liver function tests among the usual tests for confusion, and an American Family Physician review among those to consider when the diagnosis is unclear ^[10,12]. The initial tests of the HAS (2009) do not mention them ^[11].

• In addition to the tests of the "Adulte jeune : premier épisode psychotique" tab, only for atypical features (see the note), choosing the lines according to the clinical context.
• Acute or fluctuating picture (confusion, headache, vomiting, after a protein-rich meal, surgery, valproate or corticosteroids): refer to the emergency department, where serum ammonia is measured urgently.

Laboratory tests

• Caeruloplasmin and serum copper (Wilson disease)if neededTremor, dystonia, dysarthria, liver involvement, or personality and behaviour disorders in adolescents: Wilson's disease presents with psychiatric disorders in 10% of patients ^[16]. Caeruloplasmin is low in 93% of patients (threshold 0.14 g/L), but a normal value does not rule out the diagnosis ^[16].
• 24-hour urinary copper (container supplied by the laboratory)if neededSuspected Wilson's disease: 24-hour urinary copper is part of the copper studies; complete collection, in a plastic or acid-washed glass container to avoid contamination ^[16].
• Total plasma homocysteine (not reimbursed in France)if neededRapid cognitive decline, peripheral neurological involvement, thrombosis, high myopia or ectopia lentis, marfanoid habitus: homocystinuria or remethylation disorder ^[17,18]. Total homocysteine is the first-line test; it is generally above 100 µmol/L in cystathionine β-synthase deficiency, but can be lower ^[19].
• Porphobilinogen, delta-aminolaevulinic acid, porphyrins and creatinine on a spot urine sample, collected during the attack (PBG and ALA not reimbursed in France)if neededPsychiatric disorders with unexplained abdominal pain, especially cyclical, dark or red urine, constipation, confusion: acute porphyria ^[17,18], to be considered especially in women aged 15 to 50 ^[20]. A urine sample during the attack is enough; 24-hour collection is not recommended ^[20].