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Serum or Plasma Sodium Concentration (Qualitative)

Published: August 9, 2026Updated: August 16, 2026

This test evaluates whether your sodium levels in blood are too high or too low, which can affect balance and function of fluids and electrolytes in your body.

Quick summary

["A sodium imbalance may signal dehydration, kidney issues, or other health concerns."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
34696-5
Short code
Collection method Smn
Synonyms
Collection method Smn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Sodium Balance Matters

Sodium is a key electrolyte that helps regulate how fluids move in and out of your cells. Too much or too little can lead to serious health problems, like swelling, confusion, or even heart strain. This test helps doctors quickly determine if your sodium levels are outside of normal ranges, guiding treatment decisions.

How the Test Works

A small blood sample is drawn, and the sodium concentration is measured using a specialized lab technique. The result is reported as either ‘low’ (hyponatremia) or ‘high’ (hypernatremia), rather than a precise number.

Common Causes of Sodium Imbalance

Low sodium (hyponatremia) can occur from excessive sweating, vomiting, diarrhea, or kidney problems. High sodium (hypernatremia) may result from dehydration, excessive salt intake, or conditions like diabetes insipidus.

When You Might Need This Test

Your doctor may order this test if you have symptoms like confusion, muscle cramps, rapid heartbeat, or unexplained swelling. It’s also used in monitoring patients with kidney disease, heart conditions, or those receiving certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Qualitative Sodium Level Check

Frequently asked questions

What does a ‘low’ or ‘high’ sodium result mean?
A ‘low’ sodium result suggests you may have too much water in your body, which can cause swelling in tissues or brain function changes. A ‘high’ sodium result may indicate dehydration or overuse of salt. Both conditions require medical attention to prevent complications.
How soon will I get my results?
Results are typically available within 1–2 business days, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
Can I eat or drink before this test?
No special preparation is needed, but avoid excessive salt or fluids 24 hours before if instructed by your doctor.
  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 16, 2026. · Read our editorial policy