Creatinine: what is it? Understand the exam and benchmarks

When someone does those routine tests, they usually end up doing a creatinine test . This substance is synthesized from food and, under normal conditions of the organism, is eliminated.

But in some situations it can be altered. Find out what it means and how to treat it:


What is Creatinine?

Creatine is a substance resulting from the degradation of phosphorylated creatine, which is present in muscle tissue. The amount of creatine in the body is proportional to the amount of muscle – that is, the more lean mass , the more creatinine there is.

From the diet, the liver produces creatine phosphate, which serves as fuel for muscle activities. When consumed, creatinine is generated, which is released into the bloodstream.

Then it is eliminated through the urine. When laboratory tests indicate an increase in this rate, it can be a sign of a kidney problem as soon as they are responsible for filtering the blood.

What is creatinine used for in the body?

Creatinine is an inert substance in the blood, being produced and eliminated constantly by the body. If the patient has a stable muscle mass, but has an increase in the levels of creatinine in the blood, this may be a sign that the process of elimination from the body is compromised, that is, the kidneys are having some problem to eliminate creatinine from the body. blood.

If the kidneys are unable to eliminate creatinine, most likely they are also having difficulty eliminating other substances from the metabolism, including toxins. Therefore, an increase in creatinine in the blood is a sign of kidney failure.

It should be noted that creatinine is only a marker of kidney function. Therefore, it is not itself that is harmful to the organism. It goes up when the kidneys are malfunctioning.

Some other signs of kidney disease are:

  • Fatigue and sleeping problems;
  • Loss of appetite;
  • Swelling of the face, wrists, ankles or abdomen;
  • Pain in the lower back and near the kidneys;
  • Change in urinary volume and frequency;
  • Increased blood pressure.

Aminoglycoside medications (eg gentamicin ) can cause kidney damage in some people. If you are taking this type of medication, your doctor may order blood tests regularly to measure your creatinine and ensure that your kidneys are healthy.

High creatinine: what can it be?

High creatinine is a marker of kidney function. That is, the high result indicates that the organs are not having the ability to filter the blood properly. The causes can be chronic or acute.

There are some associated conditions, which can be related to eating or using medications. Among some of the causes can be:

  • High protein intake;
  • Muscle diseases;
  • Use of some medications (such as cortisone, methyldopa, trimethoprim);
  • Chronic kidney disease.

If the condition is acute, changing habits and eliminating the cause of the problem causes the kidney to recover on its own and lower creatinine rates. However, in advanced chronic cases, it may be necessary to include hemodialysis.

What is the normal rate of creatinine in the blood?

In general, creatinine values ​​above 1.6 mg / dL for men and 1.3 mg / dL for women indicate changes in renal function. It is worth remembering that every exam needs to be interpreted by medical professionals, based on the medical history of each patient.

Other factors can influence the reference values, for example age, diseases already diagnosed, use of medications and even the methodology used by the laboratory.

Risk groups for elevated creatinine

Anyone who is at risk of developing kidney disease should have a blood creatinine test. Some of these individuals fall into the risk groups below:

  • Type 1 or type 2 diabetes;
  • Hypertension;
  • People over the age of 50;
  • Family history of glomerulonephritis;
  • Family history of chronic renal failure;
  • Chronic use of anti-inflammatory drugs;
  • Frequent urinary infection or changes in urine color;
  • Repeat kidney stones;
  • Edemas without a definite cause;
  • Anemia without a definite cause;
  • Serious heart disease;
  • Loss of appetite, morning nausea, severe weakness for no apparent reason and excess weight loss;
  • Obese;
  • Smokers;
  • Children with growth problems.

How the creatinine test is done

If the doctor ordered a blood test, the material will be collected from the arm vein and the procedure is simple and quick. Then, the blood is placed in packaging tubes and taken for analysis.

However, if the doctor requests creatinine in the urine, it will be necessary to collect it every time you go to the bathroom, for a period of 12 or 24 hours, as requested.

Exam preparation

  • Although it is not mandatory, it is recommended to fast for at least three hours before collecting the blood.
  • It is important that you tell your doctor or the laboratory about medications you take regularly. This information can be useful when interpreting the exam.

Examination result:: reference values

The reference values, in general, are:

  • Children from 0 to 1 week: 0.60 to 1.30 mg / dL;
  • Children from 1 to 6 months: 0.40 to 0.60 mg / dL;
  • Children aged 1 to 18 years: 0.40 to 0.90 mg / dL;
  • In women: between 0.6 to 1.2 mg / dL;
  • In men: between 0.7 to 1.3 mg / dL.

These values ​​may have some changes, which will depend on the laboratory in which the exam is performed. Therefore, it is essential that the results are evaluated by professionals.

Low creatinine

Creatinine is a product of the breakdown of creatine, which is a muscle protein. Therefore, its low values ​​can occur in people who have less muscle mass, such as: women, the elderly and people who are sick.

Low creatinine levels may also be linked to the patient’s degree of nutrition or pregnancy.

High creatinine

When creatinine levels are high, it may be an indication that your kidneys are not working well. Your creatinine level may temporarily increase if you eat a lot of meat or take certain medications.

High creatinine can also indicate dehydration, urinary tract obstruction, methanol intoxication and some muscle diseases such as: rhabdomyolysis, gigantism and others.

If kidney damage is confirmed through medical consultations, it is important to control any conditions that may be contributing to the damage, especially blood pressure, which often requires the use of medication for proper control.

You cannot undo permanent kidney damage, however, with proper treatment, you may be able to prevent further damage.

What can affect the result

Athletes and healthy people who have high muscle mass may have higher levels of creatinine in their blood. However, elderly people tend to have less muscle mass and, therefore, may have lower levels of the substance in the blood, so the value is not interpreted as absolute. The sex, age and weight of the patient must be taken into account.

Some medications can also interfere with the result of creatinine, such as cimetidine , chemotherapy, cephalosporins, ascorbic acid , aminoglycosides and hydantoin.

How to download creatinine?

There is no specific drug to lower creatinine. Kidney recovery is possible in cases of acute kidney failure, when kidney damage is punctual. In such cases, treatment should be carried out for the disease that is causing the kidney problems.

In cases of chronic renal failure, the kidneys already have irreversible damage from years of aggression caused by other diseases. As a result, it is unlikely that there will be any type of treatment to restore kidney function and lower creatinine levels.