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Urea concentration (blood) in patients on hemodialysis at the start of the reporting period

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

This test measures the amount of urea in your blood, which helps assess how well your kidneys are filtering waste products. It’s particularly important for people on dialysis to track this level early in their treatment cycle.

Quick summary

Urea levels help monitor kidney function and dialysis effectiveness at the beginning of treatment sessions.

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

Key facts at a glance

LOINC
64325-4
Short code
INCENTERDIALYSISPATIENTSATBEGINNINGOFREPORTINGPERIOD
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

Why This Test Matters for Dialysis Patients

Urea is a waste product your kidneys normally remove from your blood. When kidneys aren’t working well—or when you’re on dialysis—the level of urea can rise. This test helps doctors check if your dialysis is working properly and if your body is clearing waste as expected.

What Urea Levels Tell Your Doctor

High urea levels may signal that your dialysis isn’t removing enough waste, or that your body is producing more waste than usual. Low levels might indicate that your kidneys are working better than expected, even if you’re on dialysis.

How This Test Is Done

A small blood sample is taken from your arm or hand. The sample is sent to a lab where it’s analyzed to measure urea concentration. This test is typically done before or at the start of your dialysis session.

What to Expect Before or After the Test

There’s usually no special preparation needed for this test. You may feel a slight pinch when the blood is drawn, but it’s a quick and common procedure. If you’re on dialysis, your doctor may schedule this test right before your treatment begins to monitor your progress.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Urea Levels and Dialysis

Short name

Urea Level (Hemodialysis Start)

Frequently asked questions

Why is this test important for someone on dialysis?
This test helps doctors track how well your dialysis is working to remove waste products like urea from your blood. High levels can indicate that your dialysis machine isn’t filtering waste efficiently, or that your body is producing more waste than usual, which may require adjustments to your treatment plan.
What does a high or low urea level mean for my health?
A high urea level may suggest that your kidneys aren’t filtering waste properly, or that your dialysis isn’t working as expected. This could lead to symptoms like fatigue, nausea, or confusion. A low urea level might mean your kidneys are working better than expected, but it’s less common in dialysis patients and could require further investigation to avoid over-filtering.
Can I influence my urea level before this test?
Yes, you can help manage your urea level by following your dialysis schedule, staying hydrated (but not excessively), and avoiding foods high in protein if advised by your doctor. Your diet and fluid intake can affect how much waste your body produces, which impacts urea levels.
  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