Creatinine: What is it? Understand the examination and reference values

Creatinine: What is it? Understand the examination and reference values

When someone makes those routine exams usually end up doing a creatinine test. This substance is synthesized from the feed, and normal conditions of the organism, is eliminated.

But in some situations it can be changed. Learn what this means and how to handle:

In this article you will find:

  1. What is creatinine?
  2. What is the creatinine in the body?
  3. High creatinine: what can be?
  4. What is the normal rate of creatinine in the blood?
  5. Risk groups for elevated creatinine
  6. How creatinine test is done
  7. Preparation for examination
  8. Result of the exam :: Reference values
  9. Which can affect the result
  10. How to download creatinine?


What is creatinine?

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

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

Then it is eliminated in the urine. When laboratory tests indicate increase in the rate can be a sign of trouble in the kidneys as soon as they are responsible for filtering the blood.

What is the creatinine in the body?

Creatinine is an inert substance in blood, being constantly produced and eliminated by the body. If the patient has a stable muscle mass, but shows an increase in creatinine levels in the blood, this can be a sign that the body’s elimination process is compromised, ie the kidneys are having trouble eliminating creatinine blood.

If the kidneys fail to eliminate creatinine, most likely they are also hard to eliminate other metabolic substances, including toxins. Therefore, an increase of blood creatinine is a sign of kidney failure.

It should be noted that creatinine is only a marker of kidney function. Therefore, it is not in itself that is bad for the body. It rises when the kidneys are malfunctioning.

Some other signs of kidney disease are:

  • Fatigue and trouble sleeping;
  • Loss of appetite;
  • Swelling of the face, wrists, ankles or abdomen;
  • Pain in the lumbar region and around the kidneys;
  • Change in volume and urinary frequency;
  • Increased blood pressure.

Drugs aminoglycosides (e.g., gentamicin) can cause kidney damage in some people. If you are taking these drugs, the doctor may order blood tests regularly to do a dosage of creatinine and thus ensure that the kidneys are healthy.

High creatinine: what can be?

High creatinine is a marker of renal 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 that may be related to food or medication use. Among some of the causes can be:

  • High protein intake;
  • Muscle diseases;
  • Use of certain drugs (such as cortisone, methyldopa, trimethoprim);
  • Kidney chronic diseases.

If the picture is sharp, change the habits and eliminate the cause of the problem causes the kidney to recover alone, 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 levels above 1.6 mg / dL for men and 1.3 mg / dl for women indicate changes in renal function. Remember that the whole examination must be performed by professionals in medicine, based on the medical history of each patient.

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

Risk groups for elevated creatinine

Any individual who is at risk of developing kidney disease should get tested for blood creatinine. Some of these individuals fit into risk groups below:

  • Diabetes type 1 or type 2;
  • Hypertension;
  • People who are old over 50;
  • Family history of glomerulonephritis;
  • Family history of chronic renal failure;
  • Chronic use of anti-inflammatories;
  • Frequent urinary infection or changes in urine color;
  • Renal repeat calculations;
  • Edema without defined cause;
  • Anemia without defined cause;
  • Serious heart disease;
  • Loss of appetite, morning nausea, intense weakness without apparent reason and excess weight loss;
  • Obese;
  • Smokers;
  • Children with growth problem.

How creatinine test is done

If the doctor has requested a blood test, the material will be collected from the arm vein and the procedure is simple and fast. Then the blood is placed inside packaging tubes and taken to the analysis.

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

Preparation for examination

  • Although it is not required, it is recommended to make a fast of at least three hours before collecting the blood.
  • It is important that you communicate your doctor or the laboratory on medications you take regularly. This information may be helpful when interpreting the exam.

Result of the exam : Reference values

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 from 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 can have some changes, which will depend on the laboratory in which the examination is done. Therefore, it is indispensable that the results are evaluated by professionals.


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

Creatinine’s low values may also be linked to the degree of patient nutrition or pregnancy.

High creatinine

When creatinine values are high, it can be an indicative that your kidneys are not working well. The creatinine level can temporarily increase if you eat a large amount of meat or take certain medications.

Creatinine high can also indicate dehydration, urinary tract obstruction, methanol poisoning and some muscle diseases such as rhabdomyolysis, gigantism and others.

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

You can not undo permanent damage to the kidneys, however, with proper treatment, you may be able to avoid larger damage.

Which can affect the result

Athletes and healthy people who have high muscle mass may have higher levels of creatinine in the blood. However, elderly people tend to have less muscle mass and therefore may have lower levels of the blood substance, so it does not interpret value as absolute. One should take into account sex, age and patient weight.

Some medications may also interfere with creatinine, such as cimetidine, chemotherapy, cephalosporins, ascorbic acid, aminoglycosides and hidantoin.

How to download creatinine?

There is no specific medicine to download creatinine. Resses recovery is possible in cases of acute renal failure, when the kidney aggression is punctual. In such cases, treatment should be performed for the disease that is causing kidney problems.

In cases of chronic renal failure, the kidneys already have irreversible lesion for years of aggression caused by other diseases. With this, it is unlikely that there is some kind of treatment that regains renal function and lower creatinine values.

Often we go to the doctor and he asks several exams we do not understand. Therefore, this article aims to help you understand what is the creatinine exam and what it serves.