Sodium
Serum sodium is very tightly regulated and shows an extremely narrow population distribution with only small shifts by age or sex.
Unit: mmol/L · 12 slices · age and sex · 1 source
Filed under panels: Electrolyte Panel · topics: Metabolic , Renal , Electrolytes
Serum sodium is the principal extracellular cation and a core component of the standard chemistry panel. It is homeostatically regulated by thirst, antidiuretic hormone, and renal handling, which keeps the population distribution exceptionally narrow. These percentiles describe the full US adult population from NHANES 2017-March 2020 rather than a screened healthy subgroup.
Population Distribution
Browse by Demographic
| Age (years) | male (mmol/L) | female (mmol/L) |
|---|---|---|
| 20-29 | 137–145 (141) | 136–144 (140) |
| 30-39 | 136–144 (140) | 136–144 (140) |
| 40-49 | 136–144 (140) | 136–144 (140) |
| 50-59 | 136–145 (140) | 136–145 (141) |
| 60-69 | 136–145 (141) | 136–145 (141) |
| 70+ | 135–145 (140) | 135–145 (141) |
Frequently Asked Questions
Why is serum sodium so narrow across the population?
Sodium concentration is tightly controlled by antidiuretic hormone, thirst, and renal water handling. Small deviations trigger strong physiologic responses, which keeps almost everyone within a narrow range.
Why is there almost no sex difference in sodium?
Sodium homeostasis is regulated by water balance rather than sex-specific pathways, so population distributions for males and females sit almost on top of each other.
Does this reflect dietary sodium intake?
No. Higher dietary sodium raises blood pressure and total body sodium but does not generally change serum sodium concentration, because the body adjusts water balance to match.