Normal reference ranges for 24-hour urinary sodium excretion during pregnancy. Values reflect expected physiologic changes in renal hemodynamics across trimesters.
| Units | Non-pregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| mmol / 24 hr | 100–260 | 53–215 | 34–213 | 37–149 |
Causes of High 24-Hour Sodium Excretion (Natriuresis)
- High dietary sodium intake
- Physiologic pregnancy hypervolemia (↑ renal blood flow)
- Diuretic use (especially loop diuretics)
- Osmotic diuresis (hyperglycemia, mannitol)
- Renal tubular disorders with sodium wasting
- Adrenal insufficiency (loss of aldosterone activity)
- Chronic kidney disease with impaired tubular sodium reabsorption
Causes of Low 24-Hour Sodium Excretion
- Low dietary sodium intake
- Volume depletion (↑ sodium retention)
- Hyperaldosteronism or excess mineralocorticoid effect
- Preeclampsia (reduced renal perfusion and sodium retention)
- Heart failure or cirrhosis
- Acute kidney injury (reduced filtration)
References
- Kratz A, Ferraro M, Sluss PM, Lewandrowski KB. Laboratory reference values. N Engl J Med. 2004;351:1548–1563. PMID: 15470219