What is the reference range for sodium in blood plasma?

1. Reference values differ for plasma, cerebrospinal fluid and urine, so the fluid must be read first. 2. Plasma sodium runs from 136 to 146 mM. 3. In cerebrospinal fluid sodium runs higher, from 138 to 150 mM. 4. Urine sodium is far wider, from 40 to 220 mM, because it reports a rate of excretion. 5. The 98 to 107 mM window belongs to plasma chloride, not plasma sodium. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 26 "Fluid, Electrolyte, and Acid-Base Balance", section 26.3 Electrolyte Balance_