Table 6.

Sensitivity, specificity, positive and negative predictive values for the detection of urinary histamine (UH) or urinary N - methylhistamine (UMH) as non-invasive markers of gastrointestinally mediated allergy (GMA)

Urinary methylhistamine (UMH) [μg/mmol creatinine x m2BSA]	Control group	Gastrointestinally mediated allergy (GMA)
>6.2*	12	70
≤6.2*	76	42
Total	88	112

*The significance level of 6.2 μg/mmol creatinine x m² BSA was calculated from the mean. + 1SD of controls during unrestricted diet. Using this criterion UMH was found to reach following test characteristics:

UMH sensitivity 70/112 = 62.5%; specificity 76/88 = 86.4%; positive predictive value 70/82 = 85.4%, negative predictive value 76/118 = 64.4%.