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Blood Test Tracker

Urine Sodium, Random

How much sodium is in a single urine sample, which swings with what you ate and drank, so clinicians read it with blood tests.

AI-verified against cited sources. Awaiting expert reviewAlso called UNa, U Na, U-NaLOINC 2955-3

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What it is

Sodium is the main salt in your blood and body fluids. Your kidneys release more or less sodium in urine to keep your salt and fluid balance steady. This test measures sodium in one urine sample, often along with a blood sodium and a urine creatinine. A single sample shows only that moment, so the number rises and falls with how much you have eaten and drunk and how concentrated your urine is.

Why it matters

A clinician may order this when your blood sodium is low or high, when you have lost fluid, or when kidney function is being checked. It helps show whether the kidneys are holding on to sodium or letting too much go. Some labs, such as Mayo, set no normal range for a random sample, because the number depends so much on diet, fluids and medicines. Quest prints a very wide one. It is most useful alongside your blood results and symptoms.

If it’s low

A lower value means the kidneys held on to sodium in that sample. This is the normal response to a low-salt diet or to losing fluid, as in dehydration, vomiting, diarrhea or heavy sweating. It can also be seen with heart, liver or kidney conditions that make the body hold on to salt and water.

Common causes

  • Little sodium in the diet
  • Dehydration, vomiting, diarrhea or heavy sweating
  • Heart failure
  • Cirrhosis of the liver
  • Chronic kidney disease or kidney failure
  • Too much aldosterone from the adrenal glands

What can help

  • Tell your clinician how much you have been drinking and whether you have had vomiting or diarrhea
  • Ask how this result fits with your blood sodium and kidney tests

If it’s high

A higher value means that sample carried more sodium. That is expected after salty food, with salt-containing fluids, and with water pills. It can also happen when the kidneys or adrenal glands lose too much sodium. Your clinician reads it with your blood sodium and with how much fluid you have lost or gained.

Common causes

  • A recent salty meal or salty drinks
  • Water pills (diuretics) or other medicines that make the kidneys release sodium
  • Salt or saline fluids given in a hospital
  • Adrenal glands that make too little of the hormones that hold on to sodium
  • Kidney conditions that waste salt (salt-losing nephropathy)

What can help

  • Ask what your result is being compared with, such as a blood sodium and urine creatinine from the same day
  • Tell your clinician about every medicine you take, including water pills

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 28–272 mmol/L. Source: Quest Diagnostics.

What can affect your result

  • Salt in your diet and how much you drank
  • Water pills and other medicines
  • Vomiting, diarrhea and heavy sweating
  • Time of day: sodium leaves faster during the day
  • How concentrated the urine is
  • The result depends on how much salt and fluid you recently took in, so a salty meal or a lot of water changes it.
  • Water pills (diuretics) and some other medicines change how much sodium the kidneys release. Tell your clinician about every medicine you take.
  • Salt or saline fluids given in a hospital raise urine sodium.
  • Very dilute or very concentrated urine shifts the concentration without changing how much sodium the kidneys release.

Any time, though the result is higher in the daytime and lower overnight. Many clinicians collect the sample at the same time as a blood sodium and creatinine. A snapshot of the moment of collection. Urine sodium can change within hours after eating, drinking, fluids or medicines.

When to talk to a clinician

A urine sodium result alone is rarely urgent. Contact your clinician promptly if you have repeated vomiting or diarrhea, trouble keeping fluids down, or severe weakness. Call 911 or your local emergency number for confusion, a seizure or fainting.

Questions you could ask

  • What is this test being used to find out in my case?
  • Could my diet, fluids or a medicine explain this?
  • How does this compare with my blood sodium?
  • Could fluid loss or a low-salt diet explain this?
  • Do my blood sodium and kidney tests need to be checked too?

Questions people ask

Why does my report show no normal range, or a very wide one, for urine sodium?

Labs such as Mayo say no reference range is established for a random urine sodium, because the result depends so much on diet, fluids and medicines. Quest prints a very wide interval. Clinicians compare it with your blood sodium and kidney tests instead.

How is this different from a 24-hour urine sodium?

A random sample shows the sodium concentration at one moment, in mmol/L. A 24-hour collection adds up all the sodium over a day, in mmol per 24 hours, so it better reflects how much sodium you eat.

Show the science and sources

Units

  • 1 mmol/L = 1 mmol/L
  • 1 mmol/L = 1 mEq/L

For clinicians and researchers

Mayo (RNAUR) states that no reference values are established for random urine sodium and that it should be interpreted with serum sodium, for example by calculating fractional excretion of sodium, FENa = (urine Na × serum creatinine) / (serum Na × urine creatinine) × 100. ARUP lists no interval for the per-volume result. Excretion tracks intake and has a marked diurnal rhythm (the overnight rate is about 20% of the daytime peak). Mayo's interpretive comment: when the kidneys lose sodium (diuretic therapy, salt-losing nephropathy, adrenal insufficiency) urinary sodium is usually above 20 mEq/L; in volume-depleted states, a value below 10 mEq/L indicates non-kidney sodium loss; in volume-overloaded states, a value below 10 mEq/L may indicate nephrotic syndrome as well as non-kidney causes. MedlinePlus describes adult values as generally above 20 mEq/L in a random sample, which varies with diet and is not a laboratory interval. Quest prints 28–272 mmol/L for the random test without creatinine. Diuretics make FENa unreliable, and fractional excretion of urea is sometimes used instead. Measured by ion-selective electrode. For sodium, 1 mEq/L equals 1 mmol/L. See Urine Sodium, 24-Hour for the timed collection, which better reflects intake.

LOINC 2955-3 (primary), 35678-2. Specimen: urine.

Sources

  1. RNAUR - Sodium, Random, Urine, Mayo Clinic Laboratories
  2. Sodium, Urine (test 0020851), ARUP Laboratories
  3. Sodium urine test, MedlinePlus Medical Encyclopedia (NIH National Library of Medicine)
  4. Sodium, Random Urine without Creatinine (test code 14522), Quest Diagnostics

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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