Creatinine in the blood what is the norm, the reasons for the increased, lowered content

Each of our movements requires energy. To obtain this energy, chemical reactions occur regularly in the body.

One of these reactions is the enzymatic breakdown of creatine phosphate. The end products are released energy phosphate and creatinine. The second element (creatinine) is used in laboratory diagnostics as an indicator of the correct functioning of the kidneys and muscles.

The rate of creatinine in the blood is a constant value, only minor fluctuations are possible. Below you will learn about this substance in the blood in more detail: what it is, what effect it has, what are the norms and what the deviations from the standard figures indicate.

crea5 - 9

What it is?

Creatine is a compound of non-protein substances that must be removed from the body.

The biochemistry of creatinine metabolism is closely related to the following substances:

  • Ammonia,
  • Uric acid,
  • Urea.

Few know what creatinine is. The chemical type of this element is as follows – C4H7N3O. It is a by-product of protein metabolism. This means that creatinine norms are a mirror image of the process of nitrogen elimination from the body.

Skeletal muscles are considered to be the main site of creatinine formation; it is found in small amounts in the brain. The source of formation is creatine phosphate. Where does it come from?

crea3 - 11Creatine is considered the start of this protein reaction. It begins its journey in the renal parenchyma. The conversion of creatine takes place in the liver. It is then transported to the muscles. Here, creatine phosphate is created from it, and then it is sent to the myofibrils.

A decay reaction occurs, one of the substances is creatinine. As a result, the energy required for muscle contraction is released. Creatinine enters the bloodstream, which carries it to the kidneys. C4H7N3O is excreted from the body along with urine.

This energy exchange takes place constantly. What does it mean? This suggests that the level of this substance in the blood is unchanged in a healthy person.

Until now, scientists have not found evidence that creatinine is toxic, although it is classified as a secondary metabolite that must be excreted from the body.

An increase in blood creatinine is a consequence of changes in the functioning of the kidneys. In diagnostics, an analysis for creatinine is often used, in particular, the Rehberg test. This is, in other words, the calculation of creatinine clearance. For this, the amount of this substance in the blood is found out and what part of it is excreted in the urine.

The rate of creatine in the blood

The level of creatinine is reflected in the biochemical blood test. The generally accepted units of measurement in this survey are micromoles per liter (μmol/L) or milligrams per deciliter. The choice depends on the research method.

Creatinine is considered normal if it matches the numbers in the table below.

Age (years)Indicator (μmol/l)
Women under 50+53
Women over 50+53

These indicators are stable, slight fluctuations are possible. As you can see from the table, the level of creatinine in the blood is lower in women than in men. This is due to less muscle tissue weight and exercise.

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Also, hormonal activity of metabolic processes can reduce the level of creatinine in the blood; in women, it differs significantly from men.

In children, as they age, the body adapts to the environment, which can lower blood creatinine. This is observed in children after a year. In adolescence, it can rise sharply again. This phenomenon is explained by puberty and hormonal activity at this time:

Age group (years)Blood creatinine (μmol/l)
Period before birth
Till 4 days+27
Up to 1 years+18

In older people, there is a decrease in the level of this substance.

This is due to processes and diseases such as:

  • Renal failure
  • Muscle tissue atrophy.

The table below reflects this process:

tabcreat - 13

The level of creatinine in the blood depends on a number of factors:

  1. Condition of the kidneys,
  2. Muscle mass,
  3. The age of the person
  4. Paul,
  5. Nutrition,
  6. Physical activity.

So men have elevated blood creatinine when compared with women. This is due to greater lean body mass. In children, the level is lower than in adults.

The boundaries of the standards for today are very conditional. For example, a female athlete will have higher blood creatinine levels compared to a male of equal weight who does not play sports.

crea1 - 15When is the analysis scheduled?

The following doctors can send you for a blood creatinine test:

  1. Nephrologist,
  2. Surgeon,
  3. Traumatologist,
  4. Urologist,
  5. Rheumatologist,
  6. Cardiologist,
  7. Endocrinologist.

A referral is issued if the patient complains about:

  • Vomiting
  • Diarrhea,
  • Thirsty
  • Lumbar pain
  • Muscle weakness
  • High pressure.

Creatinine can be elevated in the following conditions:

  1. Dystrophies,
  2. Myasthenia gravis,
  3. Poliomyelitis
  4. Diseases of the urinary tract,
  5. Hyperthyroidism
  6. Extensive injuries.

To make a more accurate diagnosis, the doctor may prescribe additional examinations. For example, with hyperthyroidism – examine the thyroid gland.


Normal readings may vary. It all depends on the gender, age of the patient, as well as on the chosen examination technique.

The most commonly used test is the Jaffe reaction. It was developed back in 1886. Naturally, over time, some adjustments and modifications were made to this technique.
For examination in the morning, a biomaterial is taken in the form of blood.

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To get the most accurate result and exclude physiological reasons for an increase in creatinine in the blood, the following recommendations must be followed:

  • Do not drink alcoholic beverages or eat meat 24 hours before visiting the laboratory,
  • On the day of the examination, try not to worry
  • Avoid physical activity.

To identify the cause of the increase in creatinine, additional studies are carried out. For example, estimation of creatinine clearance. The essence of this method is to determine the rate and volume of excretion of C4H7N3O, and this is associated with the rate of glomerular filtration in the kidneys.

For this earlier, the patient had to collect urine in one dish during the day. Today, laboratory technicians use a special calculation formula. It contains data such as the patient’s weight and age. A low level of this indicator indicates the development of renal failure in the patient.

Causes of deviations

Blood creatinine can be elevated due to physiological or pathological reasons.

Increased blood creatinine (physiological reasons):

  • Large muscle mass. If a person is actively involved in sports, then the concentration of this substance is at the upper limit, and sometimes even exceeds it,
  • Physical activity promotes the active breakdown of creatine phosphate during muscle work,
  • A high percentage of meat content in the human diet,
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It is also possible to increase the concentration of this element with drugs: tetracycline antibiotics, anti-inflammatory and cephalosporins.

Pathological factors are:

  1. Renal failure
  2. Violation of the cardiovascular system. Low pressure reduces the filtration of primary urine and, accordingly, the excretion of creatinine,
  3. Hyperthyroidism. Active secretion of the thyroid gland accelerates the breakdown of creatine phosphate,
  4. Tumor formations in muscle tissue,
  5. Significant muscle damage. This phenomenon causes the release of damaged myocytes,
  6. Radiation sickness. The cells of the body are destroyed, including muscle cells,
  7. Dehydration – a lack of fluid in the body, causes a decrease in plasma volumes, and, accordingly, an increase in the concentration of elements contained in it.

A low concentration of this element is a rare occurrence, but still occurs in medical practice.

Below is described in which cases we reduce the content of C4H7N3O in the blood:

  • Avoiding meat (veganism). The body receives much less creatinine along with food,
  • Pregnancy in the 1st and 2nd trimesters. Blood volume increases, hormonal changes occur, as a result of which the concentration of creatinine decreases,
  • Muscular dystrophy. Underdevelopment of muscle tissue leads to less excretion of creatinine into the blood stream from myocytes. Such a condition can arise due to genetic pathology or prolonged starvation, neuromuscular hereditary diseases.

How to lower creatinine levels?

A patient with increased examination results due to kidney damage has the following symptoms:

  • Pain in the lower back
  • High pressure,
  • Puffiness
  • The presence of red blood cells and protein in the urine.

With low creatinine clearance, the following symptoms may occur:

  • Confused mind
  • Dyspnea,
  • Convulsions
  • Nausea,
  • Anemia.

Treatment should first eliminate the causes of this condition, and then stabilize the level of the compound in the blood. One way to lower blood creatinine is through detoxification.

This technique involves the introduction of rheosorbilact into the body along with diuretics. It is used for normal renal activity.

With renal failure, another technique is used – hemodialysis. This is the purification of blood using a special apparatus, it is also called “artificial kidney”.

Another way to lower creatinine is through a special diet. Animal products are excluded from the diet. Optimization of the drinking regime is also important.

It will speed up the elimination of this substance along with urine. But this method is suitable exclusively for patients with normal renal activity.

You can also lower blood creatinine using folk remedies. In this case, use herbal diuretic teas. These miraculous herbs include nettle, dandelion root and sage. Only people with normal functioning kidneys can drink these teas.

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Svetlana Borszavich

General practitioner, cardiologist, with active work in therapy, gastroenterology, cardiology, rheumatology, immunology with allergology.
Fluent in general clinical methods for the diagnosis and treatment of heart disease, as well as electrocardiography, echocardiography, monitoring of cholera on an ECG and daily monitoring of blood pressure.
The treatment complex developed by the author significantly helps with cerebrovascular injuries and metabolic disorders in the brain and vascular diseases: hypertension and complications caused by diabetes.
The author is a member of the European Society of Therapists, a regular participant in scientific conferences and congresses in the field of cardiology and general medicine. She has repeatedly participated in a research program at a private university in Japan in the field of reconstructive medicine.