Skip to content

Sodium concentration in plasma or serum

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

This test measures the amount of sodium, a key mineral, in your blood plasma or serum. Sodium helps regulate fluid balance, blood pressure, and nerve/muscle function.

Quick summary

["Sodium levels help doctors check for dehydration, kidney issues, or other health conditions."]

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

Key facts at a glance

LOINC
87452-9
Short code
Sodium Spec-mCnt
Synonyms
Sodium Spec-mCnt
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
136
Ref high
145
Critical range
120 N/A – 160 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84295
SNOMED
110741000
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 if you have symptoms like excessive thirst, swelling, muscle cramps, confusion, or irregular heartbeat. It’s also used to monitor conditions like heart disease, kidney problems, or hormonal imbalances.

What to Expect Before the Test

No special preparation is needed. A blood sample is taken from a vein in your arm. If you’re on a low-sodium diet, discuss it with your doctor before the test.

What the Results Mean

Results are compared to a standard range for healthy adults. Low sodium (hyponatremia) or high sodium (hypernatremia) can signal serious health risks.

Common Causes and Conditions

Abnormal sodium levels can result from dehydration, kidney disease, excessive sweating, or certain medications. Chronic conditions like heart failure or diabetes may also affect sodium balance.

Reference range

Adult: 136-145 mmol/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 triggers a sodium test?
Symptoms like confusion, swelling, or unusual thirst, or if you have a condition like kidney disease or heart failure that affects sodium levels.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab.
Can I eat or drink before the test?
Standard blood tests don’t require fasting, but if you’re on a low-sodium diet, let your doctor know before testing.
  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