Which of the following is the most abundant extracellular ion?
Sodium is the most abundant extracellular ion, whereas potassium is the most abundant intracellular ion. Phosphate is the most abundant intracellular anion and chloride is the most abundant extracellular anion. Ref: Human anatomy and physiology By Elaine N. Marieb, Katja Hoehn, 2010, Page 625; Guyton's physiology 11th edition page 46, 358.
Calcium
Potassium
Sodium
Chloride