Non-invasive assessment of barrier integrity and function of the human gut

Table 1 Methods for the assessment of intestinal barrier integrity status and intestinal barrier function loss

Test	Measured in	Indicative for	Tissue specificity
I-FABP	Blood or urine	Intestinal epithelial integrity	Yes (predominantly proximal small gut)
	Single sample
I-BABP	Blood or urine	Intestinal epithelial integrity	Yes (predominantly ileum)
	Single sample
L-FABP	Blood or urine	Intestinal epithelial integrity	No
	Single sample
GST-α	Blood	Intestinal epithelial integrity	No
	Single sample
Claudin 3	Urine	Paracellular integrity	No
	Single sample
Dual Sugar Test	Urine	Functional intestinal barrier function	Yes
	5 h collection
PEG	Urine	Functional intestinal barrier function	Yes
	6 h collection
51Cr-EDTA	Urine	Functional intestinal barrier function	Yes
	24 h collection
LAL-assay	Blood	Intestinal barrier function	N/A
	Single sample
EndoCAb	Blood	Intestinal barrier function	N/A
	Single sample
D-Lactate	Blood	Intestinal barrier function	Yes
	Single sample

I-FABP: Intestinal fatty acid binding protein; I-BABP: Ileal bile acid binding protein; GST: Glutathione S-transferase-α; PEG: Polyethylene glycol;

⁵¹Cr-EDTA: Chromium labelled EDTA; LAL: Limulus amebocyte lysate; EndoCAb: Endotoxin core antibody; N/A: Not applicable.