Creatinine Blood Tests: A Window into Kidney Health

What is a creatinine blood test?

Creatinine blood tests are a crucial diagnostic tool used to assess kidney function and overall health by measuring how well your kidneys filter creatinine from yourblood. These tests measure the levels of creatinine, a waste product produced by your muscles when you use them.

Usually your kidneys will filter creatinine from your blood and release it through your urine. However, kidney problems can cause creatinine to build up in your bloodstream and decrease urine output. If your blood and creatinine levels are not normal, it may be a sign of kidney disease.

Why do I need a creatinine blood test?

Creatinine tests serve several important purposes:

1. Evaluating kidney function and possible kidney problems

2. Screening for kidney disease

3. Monitoring treatment progress

4. Assessing medication side effects

Healthcare providers may recommend a creatinine blood test for people with diabetes, high blood pressure, a family history of kidney disease, or other conditions that increase their risk of kidney diseases. Healthcare providers usually order creatinine tests as part of routine check-ups or when kidney problems are suspected.

What is the process of getting a creatinine blood test?

The creatinine blood test, also known as a serum creatinine test, is a simple procedure:

1. A healthcare professional draws a small blood sample from a vein, usually in the arm. (You may feel a sting when the needle goes in and out.)

2. The sample is sent to a laboratory for analysis.

3. Results are typically available within a few days.

Overall, the test usually takes less than five minutes.

If your creatinine is being measured as part of a comprehensive metabolic panel (CMP) or basic metabolic panel (BMP) test, you may need to fast for up to 12 hours before your test. Your healthcare provider may also ask you not to eat meat 24 hours before the test, as it can temporarily increase your creatinine levels.

If you take any creatine supplements, please inform your doctor, as you will likely need to stop consuming them before the test, as it will affect creatinine levels. Your healthcare provider will let you know more about how to prepare for the test based on your individual needs.

What do the results mean?

Creatinine levels are measured in milligrams per decilitre (mg/dL) of blood. Normal ranges of creatinine levels are as such:

• Adult men: 0.74 – 1.35 mg/dL

• Adult women: 0.59 – 1.04 mg/dL

• Individuals with one kidney: 1.2 – 1.9 mg/dL

Higher levels may indicate kidney problems, while lower levels are less common and may have other causes.

Your normal creatinine levels will depend on your age, muscle mass, diet, and activity level. Moreover, it is important to note that blood creatinine levels remain at a normal range during the early stages of kidney diseases and rise as the condition of your kidneys worsens.

If your doctor suspects kidney disease or damage, they may order additional tests even if your creatinine levels are normal.

What other tests do I need to consider?

Creatinine tests are often combined with other assessments:

• Estimated glomerular filtration rate (eGFR)

  • The measure of blood creatinine can also be used to estimate how quickly the kidneys filter blood. This is called the estimated glomerular filtration rate (eGFR). Blood creatinine will vary in different people, and the eGFR provides a more accurate reading on kidney function.

• Creatinine clearance test (24-hour urine collection)

  • Creatinine clearance is a measure of how well the kidneys filter creatinine out of the bloodstream. Typically, it is measured with a 24-hour urine sample at the same time as the blood sample.

These additional measures provide a more comprehensive view of kidney function.

What can affect my creatinine levels?

Several factors can influence creatinine levels:

• Intense exercise:

  • Creatinine is found in the muscles and helps them produce energy. Dehydration and muscle breakdown from exercising may cause an increase in blood creatinine levels.

• Diet (especially meat consumption):

  • Increased meat and protein consumption can affect creatinine levels by causing them to temporarily increase.

• Certain medications:

  • Antibiotics, such as trimethoprim, and H2 blockers, such as cimetidine, can cause a temporary increase in measured blood creatinine levels.

• Kidney obstruction:

  • A blockage in the urine flow, such as an enlarged prostate or a kidney stone, could cause a kidney obstruction. This blockage could create a backup of urine in the kidney and impair it's ability to function properly.

• Chronic kidney disease:

  • When kidneys are damaged, they have trouble removing creatinine from the blood, causing the blood creatinine levels to rise.

Your healthcare providers will consider these factors when interpreting test results. 

Creatinine blood tests are a valuable tool in assessing kidney health. Regular testing, especially for those at risk of kidney disease, can help detect problems early and guide treatment decisions. However, it is important to note that normal and abnormal ranges of blood creatinine levels can vary among different labs, as different labs use unique measurements or test different samples.

It is best to always consult your healthcare professional to understand your test results and their implications for your overall health.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Book an appointment with Thomson Medical today.

FAQ

What are the symptoms of kidney disease?

Symptoms of kidney disease include:

• Swelling in the hands and feet or puffy eyelids

• Dry skin, itching, or numbness

• Fatigue

• Increased or decreased need to urinate

• Bloody or foamy urine

• Loss of appetite and weight loss

• Muscle cramps

• Nausea and vomiting

• Shortness of breath

• Sleep problems

Are there any risks to a creatinine blood test?

There is very little risk to having a blood test. You may have some slight pain or bruising at the spot where the needle was inserted, but most symptoms go away quickly.

What happens if your creatinine is high?

A buildup of creatinine in the blood can be a sign of impaired kidney function. This phenomenon can lead to chronic kidney disease.

What level of creatinine is concerning?

High creatinine levels can indicate a range of underlying health conditions, including kidney infection and kidney failure. Doctors typically consider high creatinine levels to be above 1.2 milligrams per decilitre (mg/dL) for males and 1.0 mg/dL for females.

How can I lower my creatinine levels?

1. Keep blood pressure and blood sugar at normal levels.

2. Avoid strenuous exercise, like running, jogging, or swimming.

3. Eating foods with certain vitamins will also help lower creatinine levels.

4. Avoid alcohol.

5. Limit large amounts of protein and eat more fibre.

Can drinking water lower creatinine levels?

Yes. If you drink a lot of water before a blood test, it may temporarily lower creatinine levels.

Can creatinine go back to normal?

Dehydration and high protein consumption may temporarily raise creatinine levels. They will return to normal levels when a person is no longer dehydrated and reduces their protein intake.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Book an appointment with Thomson Medical today.