Table 2.

The values of sodium, urea, glucose, and potassium for the prediction of impending underhydration, and their overall diagnostic effectiveness.

ROC Index	Sodium	Urea	Glucose	Potassium
AUC	0.88	0.730	0.64	0.60
95% CI of AUC	0.85–0.92	0.68–0.78	0.59–0.70	0.54–0.65
p value	< 0.0001	< 0.0001	< 0.0001	0.002
Youden Index J	0.625	0.349	0.231	0.156
Cut-off criterion	140 mmol/L	7.52	5.61	4.57
Sensitivity (%)	0.80	0.75	0.56	0.411
95% CI of sensitivity	0.74–0.86	0.68–0.80	0.48–0.62	0.34–0.48
Specificity	0.83	0.72	0.67	0.745
95% CI of specificity	0.75–0.88	0.65–0.79	0.59–0.75	0.67–0.81
Positive likelihood ratio	4.58	2.73	1.70	1.61
Negative likelihood ratio	0.24	0.35	0.66	0.79
Difference between areas
Sodium		0.15 (0.10–0.21)	0.24 (0.18–0.30)	0.29 (0.23–0.35)
p value		< 0.001	< 0.001	< 0.001
Urea			0.09 (0.01–0.16)	0.14 (-0.06–0.21)
p value			0.02	< 0.001
Glucose				0.05 (-0.03–0.13)
p value				0.25

AUC, under the curve area; CI, confidence interval; ROC, receiver operator characteristic. Bold signifies a statistically significant value.