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24-Hour Urinary Sodium and Chloride Ratio (with Red Blood Cell Count)

Published: August 9, 2026Updated: August 17, 2026

This test measures how much sodium and chloride you excrete in urine over 24 hours, along with red blood cells in your urine sample. It helps assess kidney function and electrolyte balance.

Quick summary

["This test helps check if your kidneys are properly filtering sodium and chloride, which can affect your blood pressure and fluid balance."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
31106-8
Short code
OF .50% NaCl 24h Inc NFr RBC
Synonyms
OF .50% NaCl 24h Inc NFr RBC
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms like high blood pressure, swelling, frequent urination, or signs of kidney problems. It can also be used to monitor conditions like kidney disease, heart failure, or certain medications that affect electrolytes.

What to Expect Before the Test

You’ll collect all your urine for 24 hours in a special container. Drink enough fluids to help your kidneys pass urine normally. Avoid special diets unless instructed by your doctor.

What Happens During the Test

After collecting urine, a small sample is taken for red blood cell analysis. The sodium and chloride levels are measured in your urine over the full day.

What the Results Mean

High sodium or chloride levels may indicate kidney issues, heart problems, or improper fluid balance. Low levels could suggest kidney disease or certain medications. Your doctor will interpret results based on your health history.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

24h NaCl: RBC

Frequently asked questions

How long does it take to get my results?
Results are typically ready within 1–3 business days, depending on your lab. Follow-up with your doctor to discuss findings.
Can I eat or drink anything special before this test?
No special diet is needed, but drink enough fluids to produce normal urine output. Avoid excessive salt unless advised otherwise.
Will I need to take any medications before the test?
No special medications are required. If you’re on blood pressure or kidney medications, ask your doctor to confirm if they affect this test.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy