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Serum/Plasma Creatinine Concentration (Mass Concentration)

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

This test measures the amount 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 check: High levels may signal kidney problems; low levels could indicate dehydration or other conditions."]

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

Key facts at a glance

LOINC
47909-7
Short code
GH 30M p Arg+Ins SerPl-aCnc
Synonyms
GH 30M p Arg+Ins SerPl-aCnc
Category
hormone
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 Your Kidneys Matter

Your kidneys filter waste and extra fluids from your blood, keeping your body balanced. Creatinine is a byproduct of muscle use and is naturally removed by healthy kidneys. If your levels are too high, it may mean your kidneys aren’t working as well as they should, which can lead to long-term health risks like heart disease or nerve damage.

What Causes Changes in Creatinine Levels?

Several factors can affect creatinine levels, including dehydration (low fluid intake), muscle mass (more muscle = higher creatinine), certain medications, or kidney diseases like glomerulonephritis or diabetic nephropathy. Temporary spikes may also occur after intense exercise or from eating a high-protein meal.

When Might You Need This Test?

Doctors order creatinine tests to monitor kidney health before surgeries, during pregnancy, or if you have symptoms like swelling, fatigue, or frequent urination. It’s also part of routine check-ups for people with diabetes, high blood pressure, or a history of kidney issues.

What to Expect During the Test

This test is simple: a blood sample is drawn from a vein, usually in your arm. No special preparation is needed, but fasting isn’t required. The sample is sent to a lab for analysis, and results are typically ready within a few days.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Kidney Function and Beyond

Short name

Creatinine Level

Frequently asked questions

What does a high creatinine level mean?
A high creatinine level often indicates reduced kidney function, as your kidneys struggle to filter waste properly. This can be an early sign of kidney disease, especially if combined with other symptoms like swelling, nausea, or changes in urine output. Your doctor may also check other kidney-related tests to get a full picture.
What if my creatinine level is low?
Low creatinine levels can sometimes suggest dehydration, low muscle mass, or certain medical conditions (like liver disease). However, it’s less common to be low unless there’s an underlying issue. Your doctor may ask about your fluid intake, diet, or other health conditions to investigate further.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status. People with kidney disease, diabetes, or high blood pressure may need it more frequently, while others might only need it once a year or less. Follow your healthcare provider’s advice.
  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