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Serum Creatinine (from Serum)

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

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood serum. It helps assess kidney function.

Quick summary

["Kidney health depends on this simple blood test."]

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

Key facts at a glance

LOINC
109246-9
Short code
SMA Ab Msmt Ser
Synonyms
SMA Ab Msmt Ser
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 Is Creatinine?

Creatinine is a byproduct of muscle breakdown that your kidneys normally filter out of your blood. High levels may indicate impaired kidney function, while low levels could suggest dehydration or other conditions. Your doctor may order this test to monitor kidney health, especially if you have a history of kidney disease, diabetes, or high blood pressure.

Why Might Your Doctor Order This Test?

Doctors often check creatinine levels to evaluate kidney function, track chronic conditions like diabetes or heart disease, or monitor treatment effects. It’s also used in kidney function tests alongside other measures like blood urea nitrogen (BUN).

How Is This Test Done?

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where creatinine levels are measured using an enzymatic method. Results are typically available within 1–3 days.

What Do Results Mean?

Results are compared to a reference range based on age, sex, and overall health. Elevated levels may signal reduced kidney function, while persistently low levels could warrant further investigation for causes like dehydration or muscle loss.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

Why do some people need frequent creatinine checks?
Frequent creatinine checks help track kidney function over time, especially in people with chronic kidney disease, diabetes, or heart conditions. It’s also used to adjust medications that affect kidney function, like certain blood pressure or diabetes drugs.
What if my creatinine level is higher than expected?
Higher levels may mean your kidneys aren’t filtering waste as well. Your doctor will discuss next steps, which could include lifestyle changes, further testing, or adjustments to your treatment plan.
Can diet affect creatinine levels?
Dietary protein intake can influence creatinine levels, but the test itself doesn’t measure protein directly. If you have kidney concerns, your doctor may recommend dietary guidance to support kidney health.
  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