There creatinine it is a protein that represents the waste product resulting from the normal breakdown of muscle tissue. Creatinine is filtered through i kidneys and excreted in the urine. The feedback from low creatinine in the blood it often indicates reduced muscle mass. A low creatinine therefore must be investigated to understand if there are underlying chronic diseases.
There creatinine is a substance present in the blood, which derives from the degradation of creatine, a protein that is stored in muscle tissue and which, once phosphorylated a phosphocreatine, represents the energy reserves of muscles.
Low creatinine values
Low blood creatinine values are considered:
Creatinine below a 0.6 mg / dl (milligrams per deciliter) oa 53 µmol / l (micromoles per liter) in men
Creatinine below a 0.5 mg / dl (milligrams per deciliter) oa 44 µmol / l (micromoles per liter) in women
Creatinine below a 0.7 mg / dl (milligrams per deciliter) oa 62 µmol / l (micromoles per liter) in children
The measurement of creatinine it is very useful in medicine, as creatinine levels in the blood are used as an index of kidney function. The ability of the kidneys to eliminate creatinine is called creatinine clearance, and it's a data which can be measured directly or, more often, calculated using special formulas, and which helps to estimate the glomerular filtration rate (GFR, or Glomerular Filtration Rate) that is, the rate at which the filtrate of the kidneys is formed, an indicator of kidney function.
Normally all of our body's blood is pumped through kidneys and then comes filtered hundreds of times a day. In the kidneys, the liquid part of the blood (plasma) is conveyed through small arteries that act as tiny filters (called nephrons), which reabsorb most of the liquid that passes through them. The liquid and waste that the kidneys on the other hand do not reabsorb, and therefore do not come back into circulation, they are excreted (eliminated) in the form of urine.
As mentioned previously, the percentage of blood that passes through the kidneys and is filtered is called the glomerular filtration rate or GFR. The organs responsible for filtering blood in the kidneys are the glomeruli, that is, microscopic bundles of blood vessels inside the nephrons and constitute the fundamental part of the filtering system. The glomerular filtration rate normally cannot be measured directly, but is derived from the patient's creatinine values, age and sex using formulas such as that of Cockcroft-Gault, the Modification of Diet in Renal Disease (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI).
What are creatinine and creatinine clearance? Creatinine is a waste product that is continuously produced during normal muscle breakdown. The kidneys filter creatinine from the blood and convey it into the urine, reabsorbing almost nothing.
The amount of blood that the kidneys can clear of creatinine every minute is called the creatinine clearance.
Creatinine clearance in a young person in good health is about 120 milliliters per minute (120 ml / min). This means that 120 ml of blood are purified of creatinine every minute.
Generally, creatinine clearance is a good estimate of the glomerular filtration rate.
Obviously, if kidney function worsens, the kidneys are able to cleanse less creatinine, so we'll have high creatinine in the blood, e decreased creatinine clearance, that is reduction of glomerular filtration rate.
In other cases, much more rarely, one can be found in blood tests low creatinine, which is often associated with the finding of low urea. Below we will report causes and symptoms of low creatinine.
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Low creatinine causes
What does it mean to have low creatinine in the blood? Since creatinine is a waste product of the proteins of our muscles, the significance of the finding of low creatinine in the first case it could be a reduction in muscle mass.
Below is a list of major causes of low creatinine in adults and / or children.
- Reduction / loss of muscle mass (sarcopenia). This can be related to specific diseases, such as muscular dystrophy or other neurological diseases, but it can also be related to aging),
- Hemodilution during pregnancy: during pregnancy, the percentage of total body water changes, leading to a different concentration of blood proteins and a modification of creatinine levels in the blood. This is why the response of low creatinine in pregnancy.
- Cirrhosis of the liver: during a chronic liver disease there is a decrease in protein production and a simultaneous loss of muscle mass
- Neoplasms: tumors are often characterized by marked weight loss (cachexia) due to reduced appetite, frequent nausea and increased metabolic activity of cancer cells
- Heart failure: the anasarcatic state (i.e. the presence of a large amount of liquid that impregnates the body tissues, especially the subcutis) in the course of heart failure can lead to the dilution of substances present in the plasma, leading to the finding of low creatinine
- SIADH: fluid retention linked to a syndrome of inappropriate antidiuretic hormone secretion (SIADH).
- Low protein diet (low protein diet).
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Low creatinine symptoms
Low creatinine is not linked to specific symptoms: certainly, the presence of weight loss with loss of muscle mass can be associated with:
- asthenia (fatigue)
- hyporexia (loss of appetite) or anorexia (complete lack of appetite)
- enticement (inability to move and need to lie down all day)
- in other cases a low creatinine it does not bring any symptoms particular.
There are no specific remedies or treatments to be implemented if a low creatinine value is found, in the sense that the cause of this alteration must first be understood. Alcohol intake will therefore be suspended and liver function investigated, in addition to performing routine tests to highlight any abnormalities (usually therefore blood count, urea, sodium, potassium, calcium, AST, ALT, GGT, ALP, urinalysis, total protein protein electrophoresis, globulins and albumin assay).
What you need to make the withdrawal
Is special preparation necessary to perform the creatinine measurement?
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To take the exam it is not necessary to be fasting. It's better do not make major physical efforts in the 2-3 days before the test as these may raise blood creatinine levels.
In case of chronic medical therapy, it is advisable to inform the doctor of all the medications that are normally taken, in order to identify any active ingredients that can cause a reduction in creatininemia.
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