It is a substance that is produced during the body’s natural activity (metabolism).
It is usually excreted from the body through the kidneys. Creatinine comes from the normal wasting of muscle mass. However, a creatinine blood test does not measure muscle health. This test is used to assess kidney health.
The kidneys process creatinine and expel it from the body. If creatinine levels are higher than normal, kidney function could be affected.
This level is usually measured in kidney function tests and blood tests. Having a low level of creatinine in the blood only indicates that the kidneys are efficient and effective.
An additional test of kidney function is to collect all the urine passed over a twenty-four hour period and then compare the amount of creatinine in the blood with the level of blood flow called a creatinine clearance test.
Kidney efficiency can be seen through these tests and is generally only done if there is an indication of a problem with kidney function.
In normally functioning kidneys, the creatinine level in the urine compared to the blood must be high, as it is being distributed efficiently.
On the contrary, if the level in the urine is low, with a high level of creatinine in the blood, this indicates that there is a problem.
Tests to know creatinine levels
The amount of creatinine in the blood depends in part on the amount of muscle tissue the patient has, sex, and age.
Creatinine is a waste product that forms when creatine found in muscle is broken down.
Creatinine levels in your blood can give your doctor information about how well your kidneys are working.
Each kidney has millions of tiny blood filtering units called nephrons.
Nephrons constantly filter blood through a very small group of blood vessels known as glomeruli.
These structures filter waste products, excess water, and other impurities from the blood. The toxins are stored in the bladder and are then eliminated during urination.
Creatinine is one of the substances that the kidneys normally remove from the body. Doctors measure the level of creatinine in the blood to monitor kidney function.
High creatinine levels can indicate that your kidney is damaged and not working properly.
Creatinine blood tests are usually done in conjunction with other lab tests, such as creatinine clearance.
A creatinine clearance test measures how well creatinine is removed from the blood by the kidneys.
The blood urea nitrogen ratio test measures the amount of urea in the blood. Urea is a waste product that is made in the liver when protein is broken down in your body and excreted through urine.
Measurement of serum creatinine is the most widely used measure of kidney function.
The diagnostic utility of serum creatinine as an indicator of glomerular filtration rate is based on its constant muscle creatine production and its relatively constant renal excretion rate.
Creatinine is removed from plasma by glomerular filtration and then excreted in the urine without significant tubular reabsorption. Serum creatinine is a crude indicator of kidney disease.
Moderate creatinine levels cannot detect moderate changes in glomerular filtration rate or index.
A change in serum creatinine from 0.6 to 1.2 mg / dL reflects a 50% decrease in glomerular filtration rate, even though creatinine is still within the normal range.
If a previous baseline creatinine is not available for comparison, a serum creatinine level of 1.2 mg / dL could be considered clinically insignificant.
Serum creatinine is decreased in individuals with short stature, cachexia, amputations, or muscle disease.
Advanced liver disease causes low serum creatinine levels due to decreased hepatic conversion of creatine to creatinine, decreased dietary protein intake, loss of muscle mass, and increased renal tubular secretion of creatinine.
Patients with liver disease may have normal serum creatinine even though creatinine clearance is less than 60 ml / min.
Elderly patients have decreased muscle mass and decreased creatinine production.
The renal acute is a sudden loss of renal function that occurs several hours to days.
Increased serum creatinine concentration, accumulation of nitrogenous wastes, and decreased urinary output are hallmarks of acute renal failure.
An increase in serum creatinine level by more than 0.5 mg / dL, a 50% increase in serum creatinine over baseline, or a> 25% decrease in creatinine clearance are accepted indicators of acute renal failure.
Serum creatinine increases when the glomerular filtration rate decreases.
Causes of elevated creatinine levels include intrinsic kidney disease, urinary tract obstruction, and reduced kidney blood flow from congestive heart failure, shock, or dehydration.
In acute renal failure, serum creatinine will increase by 1 to 2 mg / dL per day. If the rate of increase is less, there is residual kidney function.
If the rate of increase exceeds 3 mg / dL per day, skeletal muscle or increased catabolism is also present.
The Rhabdomyolysis can cause a sudden increase in serum creatinine.
The ratio of blood urea nitrogen to creatinine can be used to determine the etiology of acute renal failure. Typically the ratio is 10 to 1.
The ratio generally exceeds 20 in prerenal failure due to decreased renal perfusion, such as hypertension , bleeding, or dehydration.
Post-renal diseases, such as urinary tract obstruction, also increase the ratio between 10 and 20.
It is normal (10 to 12) in intrinsic kidney disease because blood urea nitrogen and creatinine increase proportionally.
The clinical utility of this relationship is limited by nonrenal factors that increase blood urea nitrogen, such as:
- Gastrointestinal bleeding
- Parenteral nutrition.
- Glucocorticoid therapy.
Gastrointestinal bleeding increases blood urea nitrogen more than creatinine due to increased absorption of amino acids from digested blood and hypovolemia.
Normal creatinine values
A normal creatinine level depends on the amount of muscle mass you have.
A normal level for a man is higher than for a woman. Children have lower levels than men and women.
The normal values according to the age of the patient are the following:
- 0.9 to 1.3 mg / dL for adult men.
- 0.6 to 1.1 mg / dL for adult women.
- 0.5 to 1.0 mg / dL for children 3 to 18 years old.
- 0.3 to 0.7 mg / dL for children under 3 years of age.
Creatinine levels decrease during pregnancy due to an increase in the glomerular filtration rate or index.
Normal values during pregnancy are:
- First trimester of pregnancy: 0.4 to 0.7 mg / dL or 35 to 62 μmol / L.
- Second trimester of pregnancy: 0.4 to 0.8 mg / dL or 35 to 71 μmol / L.
- Third trimester of pregnancy: 0.4 to 0.9 mg / dL or 35 to 80 μmol / L.
Your serum creatinine levels may be slightly elevated or higher than normal due to:
- A blocked urinary tract.
- A high protein diet.
- Kidney problems, such as kidney damage or infection.
- Reduced blood flow to the kidneys due to shock, congestive heart failure, or complications from diabetes.
If creatinine is really high and comes from acute or chronic kidney injury, the level will not drop until the problem is resolved.
If it was temporarily or falsely elevated due to dehydration, a high protein diet, or the use of supplements, reversing those conditions will lower the level.
Also, a person on dialysis will have lower levels after one treatment.
Low creatinine levels are rare, but this can occur as a result of certain conditions that cause a decrease in muscle mass. But usually they are not a cause for concern.
Symptoms to Suggest a Creatinine Blood Test
Your doctor may order a creatinine blood test to evaluate your creatinine levels if you show signs of kidney disease.
These symptoms include:
- Have fatigue and trouble sleeping.
- Observe a loss of appetite.
- Have swelling in the face, wrists, ankles or abdomen.
- Low back pain occurs near the kidneys.
- Changes are observed in the production and frequency of urine.
- There are elevations in blood pressure.
- Nausea and vomiting occur.
These symptoms of kidney problems can be related to different diseases or conditions, including:
- Glomerulonephritis , which is an inflammation of the glomeruli.
- Pyelonephritis , which is a bacterial infection of the kidneys.
- Prostate diseases, such as an enlarged prostate .
- Blockage of the urinary tract, which may be due to kidney stones.
- Decreased blood flow to the kidneys, which can be caused by congestive heart failure, diabetes, or dehydration.
- Kidney cell death as a result of drug abuse.
- Streptococcal infections, such as post-streptococcal glomerulonephritis.
Aminoglycoside medications, such as gentamicin (Garamycin, Gentasol), can also cause kidney damage in some people.
When you are taking this type of medicine, your doctor may order regular blood tests to make sure your kidneys stay healthy.
A creatinine blood test doesn’t require much preparation.
Fasting is not necessary. You can and should eat and drink the same as normal to get an accurate result.
However, it is important to inform your doctor about prescription or over-the-counter medications that are currently being taken.
Some medications can increase your creatinine levels without causing kidney damage and interfere with test results.
The doctor should be informed if you are taking:
- Cimetidina (Tagamet).
- Nonsteroidal anti-inflammatory drugs, such as aspirin or ibuprofen (Advil, Midol).
- Chemotherapy drugs.
- Antibiotics of cephalosporin such as cephalexin and cefuroxime .
Test results may vary based on your age, gender, health history, the method used for the test, and other factors.
The test results may not mean you have a problem.
If creatinine is high, it may mean that the patient is affected by:
- Kidney disease
- Blockage in your urinary system.
- Muscle disease
- Congestive heart failure
- Overactive thyroid gland .
If creatinine is low, on the other hand, this may mean that the patient has:
- Muscle loss
- Severe liver disease
- There is not enough protein in the diet.