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Increased blood creatinine levels indicate kidney problems. If kidney disease is suspected, the creatinine is always checked.
The form of excretion of creatine is called creatinine. Creatine is important for muscle contraction and is also found in the muscles. What muscle mass a person has, what kind of life he leads, how old he is and how he eats, all of this affects the amount of creatine. This substance is formed from glycine in the liver and kidneys, increases the muscle's ability to absorb sugar and can also be absorbed through meat consumption.
Creatine is an energy-rich compound that can release energy to the muscle when needed. The excretion takes place in the form of creatinine, which is the excretion product of creatine. About 1.0 to 1.5 grams of creatinine are excreted in the urine every day. This amount is directly proportional to the muscle mass. A muscular person shows an average higher value than rather slim people. The value is also higher in men than in women and different than in children and older patients. Creatinine is completely filtered in the kidney and none of it is reabsorbed. Therefore, creatinine values are a good parameter for the filtration performance of the kidney and are always used for kidney diagnosis.
Creatinine in the blood
If kidney dysfunction occurs, it is often associated with an elimination disorder. Accordingly, less creatinine is excreted, although creatine continues to be broken down at the same time. Creatinine thus accumulates in the blood and can then be used for diagnostic purposes. This enables the so-called glomerular filtration rate to be determined.
Physiology of the kidney
The main tasks of the kidneys include the elimination of the metabolic end products urea, uric acid and creatinine. Urine formation occurs in the nephron, which consists of a kidney body and the associated finest hair tubules. Together they form the smallest functional unit in the kidney. The kidney body in turn consists of so-called glomeruli, a capsule and its capsule space. The primary urine is filtered off in the kidney body, which takes place in the glomeruli (vascular loops). In the hair canals, also called the tubular apparatus, the urine is then massively concentrated through resorption processes, which results in the secondary urine. This is the end product that is subsequently excreted.
Around 150 liters of primary urine are formed from approximately 1,500 liters of blood that flow through the kidney in one day. About 1.5 liters of urine remain of this, which is then excreted in the bladder. To filter the blood so that ultimately urine is produced, there must be a certain blood pressure inside the kidney corpuscles. In kidney disease, a change in blood pressure can help the filtration to stop working properly and therefore lead to a change in creatinine levels.
Increased blood creatinine
About 125 milliliters of blood are filtered out per minute. If this filter performance drops to 60 to 40 milliliters per minute, the blood picture changes or the creatinine value increases. If the amount of filtration lies between these areas, the deteriorating kidney function is not yet recognizable from the blood picture. As a result, creatinine is not a parameter to diagnose kidney disease early on. Nor can the severity of kidney damage be read from the creatinine level in the blood. The body can defend itself with reduced filtration ability and release some creatinine via the intestine. If the kidney recovers, for example after kidney failure, the creatinine value in the blood does not normalize in the same quick way. Here, too, the value is not necessarily an indicator of whether the kidney can properly get back to work.
To determine the filtering performance of the kidney, creatinine clearance is a meaningful method. It measures how much creatinine the kidney can release from the blood into the urine in a certain period of time. The amount of creatinine in the blood and the amount of creatinine in the 24-hour urine are used for the clearance calculation. A specific calculation formula, which also takes into account the patient's body surface (calculated from weight and height), allows an individual result. The value depends on gender, age and body surface. Falsified results occur with high protein intake, loss of muscle mass and unbalanced water balance. In these cases, the much more complex method of inulin clearance is used.
Influencing the creatinine level in the serum
The kidney damage mentioned should be mentioned here first. However, there are other factors that can influence the value. These include prolonged diarrhea, severe vomiting, long periods without hydration, large amounts of meat, muscle breakdown, hemolysis (red blood cell breakdown), heavy physical work and medications such as opiates, diuretics or cytostatics.
Creatinine levels drop during pregnancy and in diabetes. It increases due to massive meat consumption, kidney diseases, urinary stones, muscle diseases, heart failure, acromegaly (enlargement of the acra due to too much growth hormone), severe blood loss, shock and protein deficiency syndrome.
When to measure creatinine
The doctor will determine creatinine levels if you suspect kidney disease, diabetes, collagenosis (autoimmune disease, rheumatic inflammation), hypertension (high blood pressure), hemolysis and in patients who need to take medication that may damage the kidney.
Increased creatinine levels - causes
Acute kidney failure causes an increase in keratin levels. The causes of this are decreased blood flow to the kidneys, caused by shock, after burns, a sudden drop in blood pressure, sepsis (blood poisoning) and after operations. Acute kidney failure is also spoken of if the kidney has been damaged by toxins or medication.
Massive muscle breakdown, in which large amounts of muscle protein are released, is also a possible trigger for increased blood creatinine levels. Inflammation of the kidney, such as glomerulonephritis (inflammation of the glomeruli) or nephritis (inflammation of the kidney) also contributes to an increase in serum creatinine.
Chronic kidney failure is also associated with increased creatinine levels. Possible causes of chronic kidney failure include advanced diabetes that leads to kidney damage, chronic pyelonephritis (chronic inflammation of the kidney), cystic kidneys, kidney damage from long-term use of painkillers that damage the kidneys and hypertension (high blood pressure), in which diastolic ( lower) value is increased.
Symptoms of high creatinine levels
If the glomerular filtration rate (GFR) is above 60, creatinine remains within the normal range, which means that this is compensated for by the body and those affected have no complaints. With GFR values between sixty and forty, the creatinine value rises to about two milligrams per deciliter, causing fatigue, decreased performance, loss of appetite and high blood pressure.
There is talk of decompensation at a glomerular filtration rate of forty to fifteen, whereby the creatinine increases to the value of ten milligrams per deciliter and this leads to physical weakness, weight loss and pruritus (itching).
Terminal renal failure causes the GRF to drop below fifteen. The creatinine value increases to over ten milligrams per deciliter. Uremia (the occurrence of urinary substances in the blood) is a life-threatening condition. Due to the increasing urinary poisoning, abdominal pain, nausea, vomiting and diarrhea occur, often accompanied by pulmonary edema, pericarditis, brain damage and coma. When deciding whether dialysis is necessary, the creatinine value is always taken into account.
Treatment is primarily based on the underlying disease. In the case of existing kidney diseases, especially in the case of renal insufficiency (underactive one or both kidneys), a certain diet is urgently necessary. The goal is to provide less protein, which improves filter performance and also produces less toxic waste products such as urea, uric acid and creatinine. The amount of protein intake depends on the extent of renal failure, i.e. the glomerular filtration rate. It is important that the affected patients still consume enough calories with a reduced amount of protein, so that there is no malnutrition, which in turn reduces performance, increases the susceptibility to disease and ultimately reduces life expectancy.
If renal failure progresses, it has far-reaching consequences for the quality of life of the patient. Due to the poisons, sufferers suffer from chronic loss of appetite and mood swings up to depression. An individually tailored diet, which should also be tasty and easy for the patient to carry out, is therefore an important component of the treatment. Salt and fluid intake must also be tailored to the disease. Targeted nutritional therapy is therefore essential when fighting increased creatinine levels. (sw)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
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