Why Does Creatinine Matter in a Blood Test?

human kidney anatomy art illustration

Creatinine is a waste product that is produced by muscles as a result of their normal metabolism. When the kidneys are functioning properly, they filter creatinine from the blood and eliminate it from the body through urine. A blood test to measure creatinine levels in the blood is often used as a way to assess how well the kidneys are working.

Why is creatinine measured in a blood test?


Creatinine is a useful marker for kidney function because it is produced at a relatively constant rate by the body and is eliminated almost entirely by the kidneys. When the kidneys are not working properly, creatinine levels in the blood can rise. This can indicate acute or chronic kidney disease, kidney damage, or other health conditions that affect the kidneys.

A creatinine blood test can also be used to monitor the progression of kidney disease, evaluate the effectiveness of treatment, and determine the dosage of medications that are eliminated by the kidneys.

What do creatinine levels in the blood indicate?

Normal creatinine levels in the blood vary depending on factors such as muscle mass, age, and gender. In general, the normal range for creatinine in the blood is:

  • 0.6 to 1.2 milligrams per deciliter (mg/dL) for adult men
  • 0.5 to 1.1 mg/dL for adult women

Higher than normal creatinine levels in the blood can indicate that the kidneys are not functioning properly. This can be due to a number of factors, including:

  • Acute kidney injury (AKI): A sudden loss of kidney function that can be caused by dehydration, medication toxicity, or other factors.
  • Chronic kidney disease (CKD): A long-term condition in which the kidneys gradually lose function over time.
  • Kidney damage: Injury or damage to the kidneys from a variety of causes, including infections, autoimmune disorders, and certain medications.
  • Dehydration: A lack of adequate fluids in the body, which can cause the kidneys to concentrate urine and retain more creatinine.
  • High protein diet: Excess dietary protein can increase creatinine production.

How is a creatinine blood test performed?


A creatinine blood test is a simple and routine procedure that can be performed in a doctor’s office or laboratory. The test involves drawing a small sample of blood from a vein in the arm using a needle. The blood sample is then sent to a laboratory for analysis.

Before the test, it is important to inform your doctor of any medications you are taking, as certain drugs can affect creatinine levels in the blood. You may also be asked to fast or refrain from exercise before the test, as these activities can temporarily raise creatinine levels.

Closing Thoughts


Overall, a creatinine blood test is a simple and effective way to assess kidney function and monitor the progression of kidney disease. By measuring creatinine levels in the blood, doctors can diagnose and treat kidney problems before they become more serious. If you are concerned about your kidney health, talk to your doctor about whether a creatinine blood test is right for you.


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Jack Towers

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