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Serum Sodium (Electrolyte Profile)

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

This test measures the amount of sodium in your blood serum, an important electrolyte that helps regulate fluid balance and nerve function.

Quick summary

["Sodium levels help assess hydration, kidney function, and overall electrolyte health."]

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

Key facts at a glance

LOINC
34968-8
Short code
OF .20% NaCl NFr RBC
Synonyms
OF .20% NaCl 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 Is This Test Done?

Your doctor may order this test to check for dehydration, kidney problems, or conditions affecting fluid and electrolyte balance, such as heart failure, high blood pressure, or certain hormonal disorders.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on a low-sodium diet or have certain medications, let your healthcare provider know.

What the Results Mean

Results are compared to standard reference ranges, but exact values can vary by lab. Low sodium (hyponatremia) may cause headaches or confusion, while high sodium (hypernatremia) could indicate dehydration or kidney issues.

Common Conditions Linked to Sodium Levels

Abnormal sodium levels are often tied to dehydration, kidney disease, or hormonal imbalances like diabetes insipidus or Cushing’s syndrome.

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.

◆Associated findings1

Short name

Sodium Level

Frequently asked questions

What causes sodium levels to be too low?
Low sodium can result from excessive sweating, vomiting, diarrhea, kidney problems, or conditions like heart failure or syndrome of inappropriate antidiuretic hormone (SIADH).
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab. Follow-up with your doctor if you have questions or concerns.
Can diet affect sodium test results?
Yes, high-sodium foods or certain medications (like diuretics) can influence results. Avoid excessive salt intake 24 hours before testing if instructed by your provider.
  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