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Kidney health

Creatinine

Also known as: Serum creatinine test, Blood creatinine test, Creatinine level test, Often part of a comprehensive metabolic panel (CMP) or basic metabolic panel (BMP)

A creatinine test measures the level of creatinine—a waste product of normal muscle metabolism—in your blood. Healthy kidneys filter creatinine out through urine, keeping blood levels stable. When the kidneys aren’t functioning properly, creatinine builds up in the bloodstream.

This test is one of the most widely used markers of kidney function because it reflects how well your kidneys are filtering. It’s often included in a routine metabolic panel, especially for people with diabetes, high blood pressure, or a family history of kidney disease.

According to the CDC, regular testing of creatinine and related measures (such as estimated glomerular filtration rate [eGFR]) helps detect kidney problems early, when interventions are most effective.

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Key takeaways

  • Sample required: Blood (sometimes urine)

  • Tests for: Kidney filtration and waste removal efficiency

  • Typical range: 0.6–1.1 milligrams per deciliter (mg/dL) for women (ranges vary by lab and muscle mass)

What can a creatinine test tell you?

The creatinine test helps evaluate how well your kidneys filter waste from the blood. Since creatinine production is fairly constant, rising levels may suggest decreased kidney function.

Healthcare providers use it to:

  • Screen for kidney disease and monitor its progression

  • Monitor chronic conditions like diabetes or high blood pressure

  • Evaluate medication effects (e.g., nonsteroidal anti-inflammatory drugs [NSAIDs] like aspirin or ibuprofen, ACE inhibitors, diuretics, chemotherapy)

  • Check for dehydration or muscle injury

  • Guide drug dosing based on kidney clearance

What is being tested?

When the kidneys are functioning normally, blood creatinine levels stay within a narrow range. If kidney function declines, creatinine rises because the kidneys can’t remove it efficiently.

This makes creatinine levels a valuable marker for detecting both acute and chronic kidney disease.

A related test, the creatinine clearance test, uses both blood and urine samples to measure how much creatinine the kidneys excrete over 24 hours, offering a more direct estimate of filtration.

Where is the creatinine test typically included?

A creatinine test is most often included in a basic metabolic panel (BMP), which measures electrolytes, glucose, blood urea nitrogen (BUN), and creatinine to assess kidney and metabolic health. It’s also part of a comprehensive metabolic panel (CMP), a broader test that measures liver enzymes and proteins for a fuller picture of organ function. In some cases, creatinine is measured in a renal function panel, along with BUN, electrolytes, albumin, and phosphorus, to provide a more detailed view of kidney performance. Creatinine levels are also used to calculate estimated glomerular filtration rate (eGFR)—a key indicator of how well the kidneys filter waste.

Who should get a creatinine test?

You may need a creatinine test if you:

  • Have diabetes or high blood pressure

  • Take medications that affect kidney function

  • Experience swelling, fatigue, or reduced urine output

  • Have a family history of kidney disease

  • Are an older adult or have chronic conditions that strain the kidneys

The National Kidney Foundation recommends regular kidney testing (including creatinine and eGFR) for people at increased risk.

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Not available in all 50 states. Eligibility and provider order required. Lab results alone are not intended to diagnose, treat, or cure any condition. A provider will reach out about critical results and plans include access to 24/7 provider messaging.

Images for illustrative purposes only.

Frequently asked questions

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What causes changes in creatine levels? 

Creatinine levels can change for many reasons related to kidney function, muscle mass, and hydration. High creatinine often points to reduced kidney filtration from kidney disease, acute injury, or dehydration, which limits blood flow to the kidneys. It can also rise with certain medications, muscle injury, or a high-protein diet and creatine supplements.

Low creatinine is less common and typically reflects low muscle mass, malnutrition, or the natural effects of aging. Levels may also fall with severe liver disease, which can reduce creatine production and muscle protein turnover.

What is a normal creatinine level?

About 0.6–1.1 mg/dL for women, though labs vary.

Do I need to fast before the test?

No. Fasting isn’t needed, but avoid high-protein meals or vigorous exercise before your appointment.

What if my creatinine is high?

It may indicate dehydration or kidney problems. Your provider may check eGFR or urine tests for confirmation.

Can supplements affect results?

Yes, creatine and protein supplements can temporarily raise creatinine.

How often should I get tested?

People with kidney risk factors should test regularly, at least once a year.

Is the test covered by insurance?

Yes, creatinine testing is included in most standard panels. Insurance is not required with lab testing through Hers. 

What tests are related to this biomarker?

• Estimated glomerular filtration rate (eGFR)

• Blood urea nitrogen (BUN)

• Urine albumin-to-creatinine ratio (UACR)

• Comprehensive metabolic panel (CMP)

The information provided here is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always talk to a qualified healthcare provider about your specific health concerns.

Related biomarkers

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Blood Urea Nitrogen (BUN)

Blood urea nitrogen (BUN) measures the amount of urea, a waste product from protein breakdown, in your blood. Normal levels mean your kidneys are doing a good job of clearing protein waste.

Learn more about Blood Urea Nitrogen (BUN)

BUN/Creatinine Ratio

This marker compares protein waste (BUN) and creatinine to give a reading on hydration and protein metabolism. A normal ratio suggests healthy fluid balance and that your kidneys are handling protein waste well.

Learn more about BUN/Creatinine Ratio

Estimated Glomerular Filtration Rate (eGFR)

Estimated glomerular filtration rate (eGFR) measures how well your kidneys filter blood each minute. Healthy levels mean your kidneys are effectively removing waste and balancing fluids.

Learn more about Estimated Glomerular Filtration Rate (eGFR)

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Reviewed by Darragh O'Carroll, MD

Published 12/04/2025