Buying the kidney function self-test is a first step towards better health. You quickly learn how healthy your kidneys are and can immediately get started with the results.

The kidneys

The kidneys are two organs located at the back, at the level of the lower ribs. The kidneys have a number of very important tasks, including regulating water and salt balance; maintaining healthy blood pressure; stimulating the production of red blood cells; maintaining the correct acidity in the blood and, of course, filtering the blood to rid it of toxins. No less than 25% of the total blood volume flows through the kidneys every minute!

To fulfill this important task, the kidneys have an enormous capacity to filter the blood.

What is kidney function?

The kidney function self-test measures the amount of creatinine in the blood. Creatinine is a breakdown product from the muscles. It is continuously filtered out of the blood by the kidneys and excreted via the urine. It is therefore a good measure of kidney function. If the function of the kidneys is reduced, the kidneys will be less able to filter creatinine from the blood. Creatinine will remain in the blood and the value will increase.

Kidney function is estimated using a formula that includes creatinine. This estimate is called eGFR, or estimated Glomerular Filtration Rate. Kidney function is highly dependent on age and gender.

Kidney function is in fact the amount of blood that can pass through the kidney filters per unit of time. Precisely measuring kidney function is cumbersome and time-consuming. Therefore, in practice, kidney function is more often estimated using the substance creatinine. Creatinine is a breakdown product from muscles. It is continuously filtered out of the blood by the kidneys and excreted via the urine. It is therefore a good measure of kidney function. If the function of the kidneys is reduced, the kidneys will be less able to filter creatinine from the blood. Creatinine will remain in the blood and the value will increase.

What is normal kidney function?

Healthy kidneys of young people should be able to filter more than 90 milliliters of blood per minute. Older people may have lower values. It becomes dangerous when kidney function is less than 15 milliliters of blood per minute.

Symptoms of reduced kidney function

Slightly reduced kidney function causes no symptoms. Patients often only experience symptoms when there is already severe kidney failure.

Symptoms may include:

• High blood pressure and associated complaints, because the kidneys regulate the balance between fluid and salt in the body.
• Anemia, because the kidneys produce EPO, which is necessary for the production of red blood cells.
• Fatigue due to the accumulation of waste products.
• Muscle cramps due to an imbalance in electrolytes such as magnesium, sodium and potassium.
• Itching and skin problems due to the accumulation of waste products.
• Foaming urine, because proteins end up in the urine.