It occurs as a result of normal muscle metabolism.
Phosphocreatine is an energy storage molecule in muscle, it undergoes spontaneous cyclization to form creatine and inorganic phosphorus .
Creatine is then broken down into creatinine. Serum creatinine or serum creatinine is a breakdown product of creatine.
Measurement of serum or plasma creatinine concentration is included in chemical profiles, primarily to detect decreased glomerular filtration rate .
The creatinine blood test measures the level of creatinine in the blood.
Procedure for determining serum creatinine
Serum creatinine or serum creatinine is normally used to assess the functioning of the individual’s renal system.
Creatinine is removed from the body through the kidneys. When kidney function is not normal, creatinine levels rise in the blood. This test is done from a blood sample.
The patient should prepare for the test by discontinuing the use of medications that can affect the test results, including:
- The cimetidine , famotidine and ranitidine.
- Antibiotics, such as trimethoprim .
- Aminoglycosides such as gentamicin .
- Heavy metal chemotherapeutics such as cisplatin.
- Nephrotoxic such as cephalosporins .
Within the methodologies used to determine serum creatinine, colorimetric and enzymatic methods are used.
Colorimetric method (called the Jaffé reaction)
In alkaline solution, creatinine reacts with picric acid to form a yellow-orange complex.
Creatinine concentration is directly proportional to the rate of dye formation.
At present, the enzymatic method tends to be used due to its greater specificity, accuracy and precision.
This method complements the current Jaffe method, improving the accuracy of creatinine measurements in patients suffering from diabetes, kidney failure, liver failure, and diseases such as hepatitis.
The most widely used unit of measurement for creatinine concentration is milligrams per deciliter in conventional units and micromol per liter of the international system of units.
The conversion formula from (mg / dL) to micromole per liter μmol / L is as follows:
- mg / dL x 88.4 = μmol / L
Normal creatinine values
A normal result for serum creatinine values is 0.7 to 1.3 milligrams per deciliter in men and 0.6 to 1.1 milligrams per deciliter in women.
Women usually have lower creatinine levels than men.
These results are associated with the amount of muscle mass. Since women usually have a lower muscle mass than men.
The creatinine level is associated with the size and muscle mass of an individual.
When the levels that are reported are located above what is considered normal, they can be caused by:
- The obstructed urinary tract.
- Loss of body fluids or dehydration.
- Muscle problems, such as ruptured muscle fibers or rhabdomyolysis.
- Problems during pregnancy, such as seizures caused by eclampsia or high blood pressure caused by pre-eclampsia .
- Kidney problems, such as infections, acute tubular necrosis, diabetic nephropathy, glomerulonephritis, renal failure, muscular dystrophy, pyelonephritis, reduced renal blood flow, urinary tract obstruction.
When the levels reported are lower than normal, it may be due to:
- Presence of conditions such as advanced-stage muscular dystrophy or myasthenia gravis. These conditions involve the muscles and nerves and lead to a reduction in muscle mass.
- The desnutrition.
A physician may request a serum creatinine if there is a presumption in the diagnosis or the presence of the following conditions in the patient:
- Alport syndrome.
- Cholesterol embolization syndrome.
- The presence of kidney failure.
- The Cushing ‘s syndrome .
- Digitalis poisoning.
- Tonic-clonic seizures.
- Pneumorenal syndrome.
- Hemolytic uremic and hepatorenal diseases.
- La tubular interstitial nephritis.
- Lupus glomerular disease.
- Malignant arterial hypertension.
- Senior-Loken syndrome.
- Type 2 diabetes.
- Multiple myositis in adults.
- The decrease in renal perfusion.
- Macular Amyloidosis.
- Thrombotic thrombocytopenic purpura disease.
- Tumor de Wilms o nefroblastoma.