McNab et al conducted a randomized controlled double blind study in paediatric population aged 3 months to 18 years of age, comparing plasmalyte and hypotonic saline as maintenance fluid. The patients were randomly assigned into NA-140 and NA-77 group by a computer generated online randomization system. Study investigators, treating clinicians, nurses, and patients were masked to assigned fluid type throughout the study. Eligible patients were started on NA-140 or NA-70 and continued till the maintenance requirement became 50% of standard maintenance rate. When a patient had a surgical procedure before the start of intravenous maintenance fluid, the serum sodium was taken at the end of the procedure and serum electrolytes, urea, creatinine were measured after 6, 24, 48 and 72 h of treatment, until the study fluid was stopped. This study showed that 4% of participants (12 out of 322 ) allocated to Na140 developed hyponatraemia whereas 11% of participants (35 out of 319) developed hyponatremia in Na77 group (odds ratio 0.31,p=0.001). Seven patients developed severe hyponatraemia during the study with little evidence of a difference between the two treatment groups (odds ratio of 0.35, 95% confidence interval of 0.07-1.8; p=0.2). None of these children developed severe hyponatraemia. The occurrence of hypernatraemia was similar in the two groups: 14 (4%) participants developed hypernatraemia in the Na140 group, compared with 18 (6%) in the Na77 group (odds ratio of 0.80, 95% CI of 0.39-1.65,p=0.55).