Skip to content

Serum or plasma concentration of sodium (electrolyte)

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

This test measures the amount of sodium, a key electrolyte, in your blood. Sodium helps maintain fluid balance, nerve function, and blood pressure.

Quick summary

["Sodium levels help diagnose and monitor conditions like dehydration, kidney problems, or high blood pressure."]

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

Key facts at a glance

LOINC
49610-9
Short code
S pyo DNA Spec NAA+probe
Synonyms
S pyo DNA Spec NAA+probe
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 a sodium test to check for conditions like dehydration (too little fluid), excessive sweating, kidney issues, or hormonal imbalances that affect sodium levels. It’s also used to evaluate symptoms such as confusion, excessive thirst, or irregular heartbeat.

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 tested for urine sodium, you might be asked to fast or follow specific fluid restrictions beforehand.

How the Test Works

Blood is drawn and sent to a lab, where it’s analyzed to measure sodium concentration. Urine sodium tests involve collecting a sample over time to assess sodium excretion.

Possible Results and Next Steps

Results are compared to standard ranges, but exact values depend on the lab. Low sodium (hyponatremia) may cause dizziness or seizures, while high sodium (hypernatremia) could lead to dehydration symptoms like dry mouth or rapid heartbeat. Your doctor will discuss results and recommend follow-up based on your symptoms and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Sodium level

Frequently asked questions

What causes abnormal sodium levels?
Abnormal sodium levels can result from conditions like kidney disease, heart failure, excessive sweating, or hormonal disorders (e.g., adrenal insufficiency). Lifestyle factors like excessive salt intake or fluid loss (e.g., vomiting, diarrhea) can also affect sodium levels.
How often should I get this test?
Frequency depends on your health. Routine blood sodium tests are often done during general check-ups or if you have chronic conditions like heart disease or kidney problems. Your doctor may recommend more frequent tests if you’re on medications that affect sodium or have symptoms of imbalance.
Can diet affect sodium test results?
Yes, diet can influence sodium levels. High-salt intake may raise sodium, while low-salt diets may lower it. If your test is part of a monitoring plan, your doctor may provide specific dietary instructions to avoid interference.
  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