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Causes of high and low sodium in urine
Last reviewed: 04.07.2025
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Reference values (norm) for sodium excretion in urine: men - 40-220 meq/day (mmol/day); women - 27-287 meq/day (mmol/day).
Sodium is excreted from the body mainly through the kidneys. Sodium excretion is regulated mainly by hormones of the adrenal cortex and the posterior pituitary gland. Normally, sodium excretion in urine is relatively uniform throughout the day, unlike potassium excretion, which has a clear peak in the morning, and the K/Na ratio increases accordingly, which correlates with the activity of glucocorticosteroids. Aldosterone causes sodium retention in the body, increasing the K/Na ratio in urine.
Sodium is a threshold substance, and an increase in its concentration in the blood leads to an increase in its excretion. To judge the sodium balance in the body, it is necessary to simultaneously determine its content in the blood and urine.
Diseases and conditions that alter sodium excretion in urine
Increased sodium excretion |
Decreased sodium excretion |
Increased sodium intake Postmenstrual diuresis Nephritis with loss of salts Adrenal insufficiency Renal tubular acidosis (Lightwood's syndrome) Treatment with diuretics Diabetes mellitus Syndrome of inappropriate ADH secretion Alkalosis Conditions accompanied by the release of alkaline urine |
Insufficient sodium intake Premenstrual sodium and water retention Hypercorticism Extrarenal sodium loss with adequate water intake During the first 24-48 hours after surgery (stress diuresis syndrome) Conditions with decreased GFR, such as congestive heart failure Acute oliguria and prerenal azotemia, as opposed to acute tubular necrosis with oliguria |
The study of daily sodium excretion by its concentration in urine and the amount of diuresis allows us to evaluate the main physiological losses of sodium. The Na/K urine ratio is an indirect indicator of the mineralocorticoid function of the adrenal glands and in non-stressful conditions is 3-3.3.