What is Creatinine?

Creatinine is a waste product produced by the normal breakdown of creatine in your muscles. Your kidneys filter creatinine from the blood and excrete it in urine. Because creatinine is produced at a fairly constant rate and removed almost entirely by the kidneys, it is a reliable marker of kidney function.

Why is it Important?

Creatinine levels reflect how well your kidneys are filtering waste from your blood. Elevated creatinine can be an early sign of kidney disease, which often has no symptoms in its initial stages. Creatinine is also used to calculate the estimated glomerular filtration rate (eGFR), a key measure of overall kidney health.

Normal Ranges

Reference ranges vary by sex due to differences in muscle mass.

Group	Range	Unit
Adult Male	0.7 – 1.3	mg/dL
Adult Female	0.6 – 1.1	mg/dL
Adult Male	62 – 115	µmol/L
Adult Female	53 – 97	µmol/L

What Do Abnormal Results Mean?

High Creatinine

Common causes include:

Chronic kidney disease (CKD)
Acute kidney injury (dehydration, infection)
Urinary tract obstruction
High-protein diet or creatine supplements
High muscle mass (athletes, bodybuilders)
Certain medications (ACE inhibitors, NSAIDs)

Low Creatinine

Common causes include:

Low muscle mass (elderly, malnourished)
Severe liver disease
Pregnancy (increased blood volume)
Muscle-wasting conditions (muscular dystrophy)

When Should You Get Tested?

Creatinine is part of routine metabolic panels (BMP and CMP). Your doctor may order it more frequently if you have diabetes, high blood pressure, heart disease, a family history of kidney disease, or if you are taking medications that can affect kidney function.