Most people only hear about creatinine after a visit to the doctor and only if something is wrong with the functioning of the kidneys. Creatinine is a chemical breakdown product that is excreted by the kidneys. The creatinine level is therefore an important indicator of kidney function.

What is creatinine?

As already indicated, creatinine is a substance that is usually excreted by the kidneys. Creatinine is a breakdown product of creatine. About 1-2 percent of creatine is converted into creatinine and excreted from the body each day.

In figures, this is a relatively constant amount of 1.0-1.5g of creatinine per 24 hours. Creatinine itself has no function for the organism. When the kidney function decreases, the creatinine level in the blood increases because less creatinine is excreted by the kidneys. Although creatinine plays a rather minor role in the body, it is considered in laboratory medicine to be an important indicator of limitations in kidney function. Especially the so-called creatinine clearance, with which the GFR (glomerular filtration rate) can be calculated, as well as urine and plasma values play an important role.

Creatinine values

Usually, the creatinine level is measured in the blood, either in blood plasma or serum. Depending on age, muscle mass, gender and previous illnesses, the creatinine value can vary greatly. The unit for the creatinine value is given in milligrams per deciliter mg/dl or in micromol per liter μmol/l.

The normal values of creatinine are in different ranges for men and women: Men: 0.5- 1.1 mg/dl (44-97 μmol/l) Women: 0.5- 0.9 mg/dl (44-80 μmol/l) The creatinine value is determined when the functionality of the kidneys is to be checked. Especially people with suspected kidney damage or other kidney diseases are affected. The value is also a means of monitoring therapy for pre-existing conditions such as diabetes, hypertension (high blood pressure) or when taking medication that can damage the kidneys.

However, one problem with the significance of the creatinine value is that it can only be measured when the kidney function has already decreased by 50 percent, so if more serious diseases are suspected, additional parameters should be used for diagnosis. This could also be of interest to you: Kidney values

  • Men: 0.5- 1.1 mg/dl (44-97 μmol/l)
  • Women: 0.5-0.9 mg/dl (44-80 μmol/l)

To determine the creatinine level in the urine, the 24-hour urine collection procedure is used. This method is used when the so-called creatinine clearance is to be determined or certain substances are to be detected in the urine.

As the name suggests, the 24-hour urine collection procedure collects all the urine excreted over a period of 24 hours. It is important that the patient empties his bowel and bladder before time x. From then on, the patient collects the urine in a special container for 24 hours and then returns it to the laboratory for analysis. Normal values for this type of analysis are 1.0-1.3 g/day for women and 1.5-2.5 g/day for men.