Body Mass Index (BMI) is Associated with the Therapeutic Response to Oral Rehydration Solution in Children with Postural Tachycardia Syndrome.

We aimed to explore whether the body mass index (BMI) was associated with the therapeutic response to oral rehydration solution (ORS) in children with postural tachycardia syndrome (POTS). Fifty-four children diagnosed as having POTS were included in this study. Fifty-six healthy children served as the controls. Children with POTS were treated with ORS, and their treatment response was evaluated. The baseline BMI was obtained by measuring the height and weight. The Pearson correlation was made between the baseline BMI and change in heart rate from supine to upright (ΔHR) and between baseline BMI and symptom score change (post-treatment vs. pre-treatment) in the POTS group. The value of BMI in predicting the therapeutic response to ORS was assessed by analyses of the receiver operating characteristic (ROC) curve. The BMI in the POTS group was significantly lower than that in the control group (18.22 ± 3.23 vs. 20.62 ± 3.05 kg/m(2), p < 0.01). There were no statistical differences between responders and non-responders in symptom scores before treatment (p > 0.05), but symptom score was lower in responders than that in non-responders (1.52 ± 0.95 vs. 2.32 ± 1.22, p < 0.01) after treatment. The BMI in responders to ORS was significantly lower than that of non-responders (16.32 ± 2.28 vs. 20.43 ± 2.74 kg/m(2), p < 0.01). The BMI was correlated negatively with ΔHR in the POTS group (n = 54, r = -0.766, p < 0.01) and with the decrease in symptom scores after treatment in POTS patients (n = 54, r = -0.28, p < 0.05). ROC curve revealed the area under the curve to be 92.3 % (95 % confidence interval 0.829-0.996). A cutoff value of the BMI of 18.02 kg/m(2) had high sensitivity (92 %) and high specificity (82.8 %) for predicting the effect of ORS treatment for POTS. BMI is associated with the therapeutic response to ORS in children with POTS.