Why 0.9% saline is not normal

  • Mehdi RasouliEmail author
Letter to the Editor

Dear Editor

Dr. Hayes in an excellent review article of “Ab-normal saline in abnormal kidney function: risks and alternatives” has mentioned that normal saline is hypertonic capable of causing hypernatremia and metabolic acidosis [1]. Subsequently, Dr. Mortiz has discussed in the letter to the editor entitled as “Why 0.9% saline is isotonic” that normal saline is isotonic after the correction of osmolarity to osmolality [2]. There are some inadequacy in the letter of Dr. Mortiz that needs to be described.

The osmolar concentration (osmolarity) of any solution is defined as normality and is calculated as follows [ 3]:
$$ \mathrm{Osmolarity}=\frac{C\;\left(\mathrm{mg}/\mathrm{L}\right).{n}^{\prime }}{MW} $$



  1. 1.
    Moritz ML (2018) Why 0.9% saline is isotonic: understanding of the aqueous phase of plasma and the difference between osmolarity and osmolality. Pediatr Nephrol.
  2. 2.
    Hayes (2018) Ab-normal saline in abnormal kidney function: risks and alternatives. Pediatr Nephrol.
  3. 3.
    Rasouli M (2016) Basic concepts and practical equations on osmolality: biochemical approach. Clin Biochem 49:936–941CrossRefGoogle Scholar
  4. 4.
    Rasouli M, Kiasari AM, Arab S (2008) Indicators of dehydration and haemoconcentration are associated with the prevalence and severity of coronary artery disease. Clin Exp Pharmacol Physiol 35:889–894CrossRefGoogle Scholar

Copyright information

© IPNA 2019

Authors and Affiliations

  1. 1.Department of Clinical Biochemistry and Immunogenetics Research Center, Faculty of MedicineMazandaran University of Medical SciencesSariIran

Personalised recommendations