Serum biomarkers of delirium in the elderly: a narrative review

Annals of Intensive Care

Table 2 Grouping of suggested biomarkers of delirium according to their main function

Function	Assigned biomarker	Established clinical use
Cytokine	IL-1β	Inflammatory marker
	IL-2
	IL-6
	IL-8
	IL-12
	IL-18
	TNF-α
Enzyme	Adenylate kinase	Marker of liver cell damage
	ASAT	Marker of cell damage
	Cholinesterase	Marker of liver synthetic function
	CK	Marker of muscle damage
	CK-BB	Tumor marker
	LDH	Marker of tissue breakdown
	NSE	Tumor marker; brain damage marker
	PI3K
Growth factor	BDNF	Diagnosis of growth hormone deficiency; marker of pituitary function
Growth factor	IGF-1
Hormone	Cholecystokinin
	Cortisol	Marker of adrenal function
	Leptin
	Prolactin	Marker of pituitary gland/hypothalamus function; fertility assessment; tumor marker
Metabolic product	Amyloid
Metabolic product	Phenylalanine–tyrosine ratio
Neuronotrophic factor	S-100β	Tumor marker; brain damage marker
Neuronotrophic factor	SDNF
Neurotransmitter	Acetylcholine
	Dopamine
	Histamine
Transcription factor	CREB
Transport protein	Albumin	Nutritional marker, negative acute phase protein
Other	AZGP1
	BUN	Marker of kidney function
	Creatinine	Marker of kidney function
	CRP	Inflammatory marker, positive acute phase protein
	HSP70
	Metalloproteinase-9	Proinflammatory marker
	Neopterin	Marker of infection
	NLR
	Procalcitonin	Proinflammatory marker
	Protein C
	Thioredoxin
	8-iso-prostaglandin F2α

ASAT aspartate aminotransferase, AZGP1 alpha-2 glycoprotein, BDNF brain-derived neurotrophic factor, BUN blood urea nitrogen, CK creatine kinase, CK-BB creatine kinase BB, CREB cyclic AMP response element-binding protein, CRP C-reactive protein, HSP70 heat shock protein 70, IL interleukin, IGF-1 insulin-like growth factor-1, LDH lactate dehydrogenase, NLR neutrophil–lymphocyte ratio, NSE neuron-specific enolase, PI3K phosphatidylinositol-3-kinases, PCT procalcitonin, SDNF striatal-derived neuronotrophic factor, TNF tumor necrosis factor