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Sodium in the urine
Last reviewed: 05.07.2025
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Sodium in urine is an indicator of normal or altered water balance in the body. Any deviations from the normal level, which "demonstrates" potassium in urine, signal its deficiency or excess. The main reason for the violation of sodium metabolism is a sharp decrease in circulating blood flow (hypovolemia), which in turn can lead not only to pathology and damage to internal systems and organs, but also end very badly. Hypovolemia is the result of acute or chronic dehydration, internal or external bleeding, it can also be provoked by extensive burns and taking certain medications.
Sodium is an active cation that acts in the extracellular fluid, providing membrane bioelectric potential. Also, sodium is involved in stabilizing osmotic pressure, and therefore indirectly regulates arterial pressure in combination with other important elements and substances.
Sodium in urine is checked when clarifying the diagnoses of such diseases and monitoring the following processes:
- Monitoring the intake of diuretic drugs;
- Diagnosis of kidney pathology;
- Dietary nutrition adjustment;
- Diagnosis of diabetes;
- Diagnosis of the adrenal glands;
- Assessment of the condition in case of TBI (traumatic brain injury).
Sodium in urine is checked against the background of a "clean" diet, that is, as many medications as possible are excluded, except for vital ones. It is extremely important to exclude any diuretics, and if this is not possible, to take this factor into account when interpreting the test results.
Normal sodium levels in urine should be:
- Babies under one year old – 1-10 mmol/day;
- Children from one to seven years old – 10-60 mmol/day;
- Children from seven to 14 years old – 40-165-170 mmol/day;
- Over 14 years old – 130-260 mmol/day.
Sodium levels in urine may increase in the following diseases and conditions:
- Salt overload in nutrition;
- Postmenstrual diuresis, which is not considered a pathology;
- Insufficient functioning of the adrenal glands (independent or secondary);
- Chronic nephritis (with loss of salts);
- Long-term use of diuretic drugs;
- Diabetes mellitus, both type I and type II;
- Alcoholism.
Sodium in urine may be below accepted limits in the following cases:
- Salt-free zeta;
- Premenstrual syndrome;
- After surgery;
- Diarrhea;
- Excessive, pathological sweating.
Sodium in urine should be 0.3 grams less than the sodium that comes from food. For the material, urine is collected for 24 hours and stored in a special room or in a refrigerator. The method of collecting the material is standard: the first urine is disposed of and is not subject to analysis, then the urine is collected and accumulated, including the portion of the next morning. To interpret the analysis that determines sodium in urine, it is necessary to take into account that the excretion of sodium depends on the hormonal activity of the adrenal glands, as well as the pituitary gland. If these organs function normally, then sodium in the urine is excreted evenly regardless of the time of day. Potassium is highly active in the morning. The ratio of potassium and sodium is very important for diagnostics, as it shows the work of the hormonal system and the pituitary gland.
It is also advisable to evaluate sodium in urine together with a biochemical analysis of serum, since sodium itself is a threshold substance; at high concentrations, it is actively released into the blood.
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