Skip to content

Serum Creatinine (with optional 24-hour urine collection for creatinine clearance calculation)

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

This test measures the level of creatinine, a waste product from muscle metabolism, in your blood. It helps assess how well your kidneys are filtering blood.

Quick summary

["Kidney function and waste removal depend on this test result."]

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

Key facts at a glance

LOINC
21345-4
Short code
HTLV I+II Ab CSF Ql IB
Synonyms
HTLV I+II Ab CSF Ql IB
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order a serum creatinine test to check for kidney problems, monitor kidney function over time, or evaluate conditions that affect kidney health, such as diabetes or high blood pressure. It can also help determine how well medications are being processed by your kidneys.

What to Expect Before the Test

No special preparation is needed for a standard serum creatinine test. For a 24-hour urine creatinine test, you’ll collect all urine over 24 hours in a container, starting after your first urine of the day. Follow your healthcare provider’s instructions carefully to ensure accurate results.

How the Test Is Performed

A blood sample is taken from a vein, usually in your arm, using a small needle. You may feel a brief sting, but it usually doesn’t cause much discomfort. The test is quick and typically done in a lab setting.

What the Results Mean

Higher than normal levels may indicate kidney problems, poor kidney function, or conditions that increase muscle breakdown. Lower levels might suggest dehydration or overhydration. Your doctor will interpret results in relation to your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum Creatinine

Frequently asked questions

How often should I get this test?
Your doctor will determine the frequency based on your health condition, symptoms, and medical history. For example, people with chronic kidney disease may need regular monitoring, while others may only need it occasionally.
Can diet or exercise affect my creatinine levels?
Diet high in protein can temporarily raise creatinine levels, so your doctor may advise limiting protein intake before testing if needed. Exercise itself doesn’t usually change creatinine levels, but intense physical activity shortly before testing could slightly impact results.
What if my creatinine levels are abnormal?
If your levels are high, your doctor may recommend further tests, like a kidney ultrasound or additional blood tests, to investigate the cause. If low, they might check for dehydration or other conditions affecting fluid balance.
  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