I read with interest the hypothesis regarding the determinants of the plasma water sodium concentration by Nguyen and Kurtz [1]. The authors have highlighted the importance of parameters other than total exchangeable sodium, total exchangeable potassium and total body water (TBW) as determinants of plasma water sodium concentration. However, there seems to be an error in the calculation of the y-intercept.
The authors have derived the equation:
![]() |
![]() |
![]() |
The authors have used two examples to highlight the clinical application of their hypothesis. In both of the examples, the authors have not considered insensible water losses while calculating TBW2. If they had done so, then the predicted [Na+]p would have been higher than the actual value.
While the authors have highlighted some important concepts, these might require modifications to accurately predict the changes in plasma water sodium concentrations with therapeutic interventions.
Conflict of interest statement. None declared.
Department of Pediatrics All India Institute of Medical Sciences New Delhi India Email: rakesh_lodha{at}hotmail.com
References