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Serum or Plasma Mass Concentration of Creatinine

Published: August 9, 2026Updated: August 17, 2026

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

Quick summary

["A creatinine test helps check how well your kidneys are filtering waste from your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
785-6
Short code
MCH RBC Qn Auto
Synonyms
MCH RBC Qn Auto
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
automated-count
CPT
85041
SNOMED
900000000000003001
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 Is Done

Your doctor may order this test to monitor kidney health, especially if you have symptoms like swelling, fatigue, or changes in urine output. It’s also used during pregnancy, before certain surgeries, or to evaluate chronic conditions like diabetes or heart disease.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before testing if it’s part of a broader metabolic panel. Wear comfortable clothing and plan to stay near the lab for a short time.

How the Test Is Performed

A healthcare provider will collect a blood sample from a vein in your arm using a small needle. You may feel a brief pinch, but the procedure is quick and usually painless. The sample is then sent to a lab for analysis.

What the Results Mean

Results are compared to a reference range, which can vary by lab. High levels may indicate kidney problems, while very low levels could suggest muscle disorders or other conditions. Your doctor will interpret results in the context of your overall health.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

How often should I get this test?
The frequency depends on your health status. Healthy adults may get it once every few years, while people with kidney disease, diabetes, or heart conditions may need it more often—typically every 6 to 12 months, as directed by your doctor.
Can diet affect my creatinine levels?
Yes, high-protein foods or muscle breakdown (e.g., from intense exercise or illness) can temporarily raise creatinine levels. Avoiding excessive protein for a day or two before testing may help stabilize results, but always follow your doctor’s advice.
What if my results are outside the normal range?
If your results are abnormal, your doctor will discuss next steps, which may include additional tests (like urine tests) or adjustments to your treatment plan. Never interpret results alone—always share them with your healthcare provider.
  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 17, 2026. · Read our editorial policy