We thank the author for his interest and comments on our paper [1]. He has raised some very valid points. We had highlighted in our article that the risk of hyponatremia with use of hypotonic fluids was almost twice that with use of isotonic fluid (RR 0.48, 95% CI 0.27, 0.83; P= 0.01). The risk difference and the number-needed-to-harm (NNH) have been summarized in Table I [1]. As rightly pointed out, the NNH for hyponatremia was higher (1 in 4) compared to study by Montana, et al. [2] (1 in 7), possibly because their trial used same volume fluids in both groups. Similarly from the data of Kanan, et al. [3], figures for NNH would be 1 in 7 with isotonic fluid in standard volume and 1 in 9 when reduced volume hypotonic fluid is used. Higher figures of NNH in our study underline the additional benefit of reducing the volume of maintenance fluids apart from using isotonic solutions. Kanan, et al. [3] also showed that use of isotonic saline in ‘standard volume’ reduced the risk of hyponatremia by 12.6% compared to hypotonic fluid, whereas reducing the volume of hypotonic fluids also resulted in a risk difference of 10.5%. Our study demonstrated the cumulative effect of using isotonic fluid in reduced volume but there was no comparative ‘standard volume’ isotonic fluids group to demonstrate the benefit of either strategy.

TABLE I Risk of Hyponatremia with Hypotonic vs Isotonic Maintenance Fluid 

We agree that same amount of potassium was not used in both arms of this study. If the same amount of potassium were to be used in both groups, the concentration of potassium would have been 60% higher in the isotonic fluids group (33.3 meq/L as against 20 meq/L). Moreover, this would have also increased the tonicity of the fluid by approximately 7.5%. For maintaining infusion concentration at 20 meq/L, potassium supplementation needed to be reduced.

We agree that urine osmolality should also have been measured to estimate free water clearance and could have explained hyponatremia despite using isotonic fluids.

1. Shamim A, Afzal K, Manzir AS. Safety and efficacy of isotonic (0.9%) vs. hypotonic (0.18%) saline as maintenance intravenous fluids in children: A randomized controlled trial. Indian Pediatr. 2014;51:969-74.

2. Montanana PA, Modesto AV, Ocon AP, Lopez PO, Lopez PJL, Toledo PJD. The use of isotonic fluid as maintenance therapy prevents iatrogenic hyponatremia in pediatrics: a randomized, controlled open study. Pediatr Crit Care Med. 2008;9: 589-97.