Applying the same method for assessing the test utility [12], the serum Arg-1 concentration reached the threshold criteria for replacement test discriminating endometriosis patients from healthy controls—showing sensitivity of 94.2% and specificity of 73.6% with a cutoff for Arg-1 concentration of 38.5 ng/ (meeting the criteria for sensitivity ≥ 94% and specificity ≥ 79%). Here, ARG1 is linked to endometriosis.