Creatinine (CREAT)

What is Creatinine?

Creatinine is a waste product produced by muscle metabolism that’s filtered out of the blood by the kidneys. Because it’s produced at a relatively constant rate and eliminated only through the kidneys, creatinine serves as a reliable marker of kidney function and is the basis for calculating estimated glomerular filtration rate (eGFR).

Why is it Tested?

Doctors order creatinine to assess kidney function, monitor chronic kidney disease progression, and screen for kidney damage before symptoms appear. It’s essential for medication dosing, as many drugs require dose adjustments based on kidney function. Regular monitoring helps detect early kidney problems in people with diabetes or high blood pressure.

Normal Ranges

Reference ranges vary by lab, age, and sex. General adult guidelines:

Men: 0.6–1.2 mg/dL
Women: 0.5–1.1 mg/dL

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low Creatinine

Low levels are uncommon but may indicate:

Low muscle mass or malnutrition
Severe liver disease
Pregnancy (due to increased kidney filtration)

High Creatinine

Elevated creatinine suggests reduced kidney function and may point to:

Chronic kidney disease
Acute kidney injury
Dehydration
Certain medications (NSAIDs, ACE inhibitors)

How to Track Over Time

Tracking creatinine over time reveals kidney function trends that single measurements can miss. A gradual rise may indicate developing chronic kidney disease, while sudden increases suggest acute kidney injury requiring immediate attention. Changes as small as 0.3 mg/dL can be clinically significant.

Creatinine