Muscle metabolism generates creatinine at a constant rate. Creatinine is generated from creatine which plays an important role in the production of energy in muscles. Creatinine is actually a chemical waste and so, it is present in urine in small amounts. Creatinine is transported through bloodstream and it is filtered out by the kidneys. It is then disposed of through urine. Day-to-day changes in muscle mass are negligible. So, the blood creatinine level should not change every day. Only about 2% of the body's creatine is converted to creatinine every day.
As kidneys are responsible for maintaining the normal range of blood creatinine, creatinine level is found to be the reliable indicator of kidney function. Elevated levels of blood creatinine indicate that there is poor clearance of creatinine by the kidneys. Abnormally high level of blood creatinine can be the indicator of possible failure of kidneys. During routine and standard blood tests, the amount of creatinine in blood is therefore checked. Urine creatinine levels also help access kidney function. The exact amount of creatinine clearance (CrCl) can be the precise measure to judge whether the kidneys are functioning smoothly or not. Estimation of glomerular filtration rate (GFR) helps evaluate kidney function.
Normal Blood Creatinine Levels
- In adult men: approximately 0.6 to 1.2 mg/dl ( milligrams/deciliter)
- In adult women: approximately 0.5 to 1.1 mg/dl
- In a person with only one kidney: approximately 1.8 to 1.9
- Infants: approximately 0.2 to 1.2 mg/dl depending upon their muscle development
- Children: approximately 0.3 to 0.7 mg/dl depending upon their muscle development.
- Teenagers: approximately 0.5 to 1.0 mg/dl depending upon their muscle development
Muscular people or middle-aged people may have more blood creatinine than the normal people, while the elderly people may have less creatinine, depending upon the muscular growth. Sick people, people facing malnutrition or people opting for drastic weight loss where muscle mass can diminish, may have lower than normal levels of blood creatinine. Pregnant women might have low creatinine. Once you know about the normal levels, you can identify the change in creatinine levels easily. Dehydration, shortness of breath, fatigue, change in mental status are some of the common symptoms of high blood creatinine but the symptoms may vary from person to person.
Causes of High Blood Creatinine Levels
As we have seen, kidney dysfunction is the main cause of elevated creatinine levels. High blood creatinine levels like 2.0 or more in infants and 10.0 or more in adults suggest severe kidney impairment. These patients need to undergo 'dialysis' which facilitates removal of wastes from the blood. But what are the conditions that lead to kidney dysfunction? Here is an overview of the causes of kidney dysfunction.
- High Blood Pressure: Persistent high blood pressure or hypertension is the common cause of kidney problems.
- Diabetes: Diabetes, over the years, affects the function of the kidneys seriously. It eventually can raise blood creatinine.
- Side Effect of Medicines: Certain drugs are responsible for high amount of creatinine in blood.
- Consumption of Meat: Consumption of large amount of dietary meat can lead to excess creatinine in blood.
- Urinary Tract Obstruction: If formation of kidney stones leads to an obstruction in the urinary tract or if any other condition results in urinary tract obstruction, then blood creatinine levels can rise.
- Dehydration: Dehydration can lead to high blood creatinine.
- Excessive Blood Loss: Excessive blood loss that can cause a shock, may lead to dysfunction of kidneys.
- Gout: Gout, a type of arthritis, can lead to damaged kidneys.
- Muscle Conditions: Rhabdomyolysis, gigantism, muscular dystrophy, myasthenia gravis etc. can damage the kidneys.
- Kidney Infection: Kidney infection can increase the amount of creatinine in blood.
Test results may show increased blood creatinine levels, but this does not help know why the body is producing more creatinine or why the body is not filtering out creatinine in a proper way. Other tests such as urine test, X-rays or scans help find out the reasons behind elevated creatinine levels. Children with high blood creatinine should be assessed by a pediatric nephrologist, as there can be problems related to growth, bone and metabolic disorders. In any case, high blood creatinine levels need prompt medical attention.