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Serum electrolytes and renal function panel (with creatinine and urea nitrogen)

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

This blood test checks how well your kidneys are working by measuring key substances in your blood, including electrolytes and waste products.

Quick summary

Kidneys filter waste from your blood; these tests help ensure they’re functioning properly before starting dialysis.

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

Key facts at a glance

LOINC
64329-6
Short code
HOMEPATIENTSSTARTINGDIALYSISFORFIRSTTIMEEVER
Synonyms
—
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

What This Test Measures

Your blood will be drawn to check for sodium, potassium, chloride, bicarbonate (to monitor fluid balance and acid-base status), creatinine (a waste product filtered by kidneys), and blood urea nitrogen (BUN, another waste product). These help assess kidney function and electrolyte levels.

Why It Matters Before Dialysis

These tests are critical before starting dialysis because they help doctors determine if your kidneys are failing enough to require this treatment. They also identify any electrolyte imbalances or kidney damage that may need correction before beginning dialysis.

What to Expect During the Test

A simple blood draw is performed in a clinic or lab. The process takes a few minutes, and you’ll feel a brief pinch. No special preparation is needed, but fasting may be advised for some components.

When to Expect Results

Results are typically available within 1–3 business days. Your doctor will discuss them with you during your follow-up appointment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal results may indicate kidney damage, fluid overload, electrolyte imbalances, or other health issues that require medical attention. These tests help guide your treatment plan to ensure safe and effective dialysis.

Short name

Basic kidney function tests

Frequently asked questions

How often will I need this test?
This test is usually done once before starting dialysis and then regularly (e.g., monthly or as needed) to monitor kidney function and adjust treatment.
Will I need to prepare for this test?
No special preparation is required, but some components (like creatinine) may require fasting. Your healthcare team will provide specific instructions if needed.
What if my results are abnormal?
If results show kidney issues or imbalances, your doctor will work with you to address them—this might include adjusting medications, diet, or timing of dialysis sessions.
  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