Creatinine is a waste product from the breakdown of muscle tissue. It is filtered out of the blood by the kidneys and excreted in the urine. Measuring the creatinine level in the blood and urine helps to assess kidney function. Normal values in blood are 65-120 µmol/L (0.74-1.35 mg/dL) for men and 52-92 µmol/L (0.59-1.04 mg/dL) for women, while in urine they are 1768-28,000 µmol/L (20-320 mg/dL) for men and 1768-24,300 µmol/L (20-275 mg/dL) for women.

The kidneys play an important role in the body, such as in the production of hormones, maintaining an optimal fluid balance, and filtering waste. With Homed-IQ’s Liver and Kidney Function Test you can check several biomarkers that indicate overall kidney health, including your creatinine value.

What is creatinine?

Creatinine is a waste product made by the muscles. As it is produced, creatinine enters your bloodstream and is filtered and broken down in the kidneys. A small amount of creatinine is excreted in the urine. This creates a balanced level in the blood, which is determined by the speed of creatinine production in the muscles and breakdown/excretion by the kidneys (De Prostaatkliniek).

What does creatinine value indicate?

Your creatinine value provides insight into the functioning of the kidneys. There is a constant concentration of creatinine in the blood. Therefore, the creatinine value is an excellent indicator to determine whether the kidneys are functioning properly. One’s blood creatinine value determines the amount of waste products in the blood. With this value it is possible to estimate the amount of blood that the kidneys filter per minute (eGFR) (Health and Science, 2018).

What is a normal creatinine value?

Creatinine can be measured in both blood and urine, either by a simple urine sample or as part of a 24-hour urine sample. The amount of creatinine in the urine excreted and collected over 24 hours is determined. The corresponding normal values can be found in the table. Both µmol/L and mg/dL are given as different regions and laboratories use different units of measurement.

A normal blood creatinine value differs from person to person, with men usually having a higher creatinine level than women. This is because men have more skeletal muscle. Likewise, a person with more muscle has a higher creatinine value than a person with less muscle.

How high can creatinine in urine be?

Creatinine in urine can reach up to 320 mg/dL (2830 µmol/L) in men and 275 mg/dL (2430 µmol/L) in women in a random spot sample. For a 24-hour urine test, levels can go as high as 2.5 g/24h (22 mmol/24h) for men and 2.0 g/24h (18 mmol/24h) for women.

What does low creatinine mean?

A low creatinine level in the blood usually indicates reduced muscle mass, as creatinine is a waste product of muscle metabolism. This is often seen in people with muscle wasting, older people or people suffering from malnutrition. It can also be an indication of severe liver disease, where creatinine production is reduced due to impaired liver function. In some cases, pregnancy can lower creatinine levels (Dutch Journal of Medicine, 1990).

A low creatinine value in the urine usually indicates impaired kidney function or poor filtration performance. It is possible that the kidneys are not removing enough creatinine from the bloodstream, which may indicate chronic kidney disease. A low creatinine level in the urine can also occur if the urine is too dilute, which is often due to excessive fluid intake or certain medications that increase urine excretion.

What does high creatinine mean?

A high creatinine level in the blood is usually a warning sign of kidney dysfunction or damage. The kidneys are responsible for filtering waste products such as creatinine from the blood, and elevated levels indicate that they are not fulfilling this function effectively. Chronic kidney disease, acute kidney injury or conditions such as high blood pressure and diabetes can lead to persistently high creatinine levels. Other causes include a lack of fluids, which leads to an accumulation of creatinine in the blood, or a high-protein diet, which can temporarily increase the level. Immediate medical attention is required to determine the severity and underlying cause of the elevated creatinine level.

A high creatinine level in the urine can occur when the kidneys excrete large amounts of creatinine, which can indicate excessive muscle breakdown or a high protein intake. It can also be the result of dehydration, where the urine is enriched with waste products such as creatinine. In athletes or people with high muscle mass, a high creatinine value in the urine can be normal, as the muscle metabolism naturally produces more creatinine. However, consistently high levels can also indicate kidney overload or an underlying metabolic disorder, so it is important to investigate the cause with additional tests.

Testing Creatinine Levels 

Testing creatinine levels provides a snapshot of your kidney function. With Homed-IQ’s Liver and Kidney Function Test, you can measure your creatine levels and other important values from home. This blood and urine test provides insight into the following values: ALT, AST, GammaGT, Bilirubin, Albumin, Creatinine, eGFR and Alkaline Phosphatase. In this way, you get as complete a picture as possible of both your kidneys and liver health. The advantage of testing creatinine with a home test is that you do not have to go to the doctor. The analysis of the creatinine value and other biomarkers takes place in a certified laboratory.

The causes of a creatinine level that is too high

A creatinine value that is too high can have various causes. For example, a sports injury that caused muscle damage, or kidney stones. Reduced kidney function can also be caused by prostate problems, bacterial infections that result in kidney inflammation, or complications due to diabetes. It is also possible that the use of certain drugs reduces kidney function.

Are there any diseases related to elevated creatinine?

There are several diseases related to elevated creatinine, such as diabetes and high blood pressure. Additionally, there are several kidney diseases that can lead to kidney failure, which causes the blood creatinine level to rise.

The consequences of a creatinine level that is too high

Symptoms of high creatinine are not always noticeable. In the early stages of kidney or liver damage, there are usually no symptoms. At a later stage you may suffer from:

• Itch
• Nausea
• Fatigue
• Lowered immunity

How do I lower my creatinine level?

Blood creatinine can be lowered in various ways. For example, it is possible to address contributing health conditions such as high blood pressure. In that case, it is important to eliminate salt from your diet as much as possible. Your doctor can also prescribe medication to lower blood pressure. In addition to salt, it is also advisable to limit proteins with high blood pressure. Quitting smoking and weight loss (if you are overweight) can also help lower creatinine. In addition, it is advisable not to use painkillers such as NSAIDs if your creatinine is high, as they have a negative effect on kidney function (Kidney Foundation).