Creatinine has been found to be a fairly reliable indicator of kidney function.
Why are blood creatinine levels checked?
Creatinine has been found to be a fairly reliable indicator of kidney function.Source: MedicineNet/iStock
The kidneys maintain the blood creatinine in a normal range. Creatinine is a fairly reliable indicator of kidney function. Elevated creatinine level signifies impaired kidney function or kidney disease.
As the kidneys become impaired for any reason, the creatinine level in the blood will rise due to poor clearance of creatinine by the kidneys. Abnormally high levels of creatinine thus warn of possible malfunction or failure of the kidneys. It is for this reason that standard blood tests routinely check the amount of creatinine in the blood.
A more precise measure of kidney function can be estimated by calculating how much creatinine is cleared from the body by the kidneys. This is referred to as creatinine clearance and it estimates the rate of filtration by kidneys (glomerular filtration rate, or GFR). The creatinine clearance can be measured in two ways.
- It can be calculated (estimated) by a formula using serum (blood) creatinine level, patient's weight, and age. The formula is 140 minus the patient's age in years times their weight in kilograms (times 0.85 for women), divided by 72 times the serum creatinine level in mg/dL.
- Creatinine clearance can also be more directly measured by collecting a 24-hour urine sample and then drawing a blood sample. The creatinine levels in both urine and blood are determined and compared.
Normal creatinine clearance for healthy women is 88-128 mL/min. and 97 to 137 mL/min. in males (normal levels may vary slightly between labs).
Blood urea nitrogen (BUN) level is another indicator of kidney function. Urea is also a metabolic byproduct that can build up if kidney function is impaired. The BUN-to-creatinine ratio generally provides more precise information about kidney function and its possible underlying cause compared with creatinine level alone. BUN also increases with dehydration.
Recently, elevated creatinine levels in infants were associated with bacteremia while elevated levels in adult males have been linked to an incresed risk of prostate cancer.
Chronic Kidney Disease Symptom
High Creatinine Level
Early kidney disease is a silent problem, like high blood pressure, and does not have any symptoms. People may have CKD but not know it because they do not feel sick. A person's glomerular filtration rate (GFR) is a measure of how well the kidneys are filtering wastes from the blood. GFR is estimated from a routine measurement of creatinine in the blood. The result is called the estimated GFR (eGFR).
Creatinine is a waste product formed by the normal breakdown of muscle cells. Healthy kidneys take creatinine out of the blood and put it into the urine to leave the body. When the kidneys are not working well, creatinine builds up in the blood.
High creatinine levels that reach 2.0 or more in babies and 5.0 or more in adults may indicate severe kidney impairment.Source: iStock
What are considered high and low creatinine levels?What are normal blood creatinine levels?
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| High creatinine levels that reach 2.0 or more in babies and 5.0 or more in adults may indicate severe kidney impairment.Source: iStock |
What are considered high and low creatinine levels?
Normal levels of creatinine in the blood are approximately 0.6 to 1.2 milligrams (mg) per deciliter (dL) in adult males and 0.5 to 1.1 milligrams per deciliter in adult females. (In the metric system, a milligram is a unit of weight equal to one-thousandth of a gram, and a deciliter is a unit of volume equal to one-tenth of a liter.)
- A person with only one kidney may have a normal level of about 1.8 or 1.9.
- High creatinine levels that reach 2.0 or more in babies and 5.0 or more in adults may indicate severe kidney impairment.
- The need for a dialysis machine to remove wastes from the blood is based upon several considerations including the BUN, creatinine level, potassium level, and how much fluid the patient is retaining.
- Low creatinine levels indicate malnutrition, severe weight loss, long term illness, and low muscle mass such as in the elderly and infant
The most common causes of longstanding (chronic) kidney disease in adults are high blood pressure and diabetes.Source: iStock
What are the symptoms associated with high creatinine levels?
The symptoms of kidney dysfunction (renal insufficiency) vary widely. They generally do not correlate with the level of creatinine in the blood.
- Some people may have an incidental finding of severe kidney disease and elevated creatinine on routine blood work without having any symptoms.
- In others, depending on the cause of the problem, different symptoms of kidney failure may be present including:
- feeling dehydrated,
- fatigue,
- loss of appetite,
- Insomnia,
- excessive urination or lower than normal urination,
- swelling (edema),
- shortness of breath,
- confusion, or
- many other nonspecific symptoms (for example, nausea, vomiting, neuropathy, and dry skin).
Kidney infections, rhabdomyolysis (abnormal muscle breakdown) and urinary tract obstruction may also elevate creatinine levels.Source: iStock
What causes elevated (high) creatinine levels in the blood?
Any condition that impairs the function of the kidneys is likely to raise the creatinine level in the blood. It is important to recognize whether the process leading to kidney dysfunction (kidney failure, azotemia) is longstanding or recent. Recent elevations may be more easily treated and reversed.
The most common causes of longstanding (chronic) kidney disease in adults are
Other causes of elevated blood creatinine levels are:
- Certain drugs (for example, cimetidine [Bactrim]) can sometimes cause abnormally elevated creatinine levels.
- Serum creatinine can also transiently increase after ingestion of a large amount of dietary meat; thus, nutrition can sometimes play a role in creatinine measurement.
- Kidney infections, rhabdomyolysis (abnormal muscle breakdown), and urinary tract obstruction may also elevate creatinine levels.
Who has low or high blood creatinine levels?
- Muscular young or middle-aged adults may have more creatinine in their blood than the norm for the general population.
- Elderly persons may have less creatinine in their blood than the norm. Infants have normal levels of about 0.2 or more, depending on their muscle development.
- In people with malnutrition, severe weight loss, and long-standing illnesses, the muscle mass tends to diminish over time and, therefore, their creatinine level may be lower than expected for their age.
Top Creatinine Blood Test Related Articles
The body produces various harmful chemicals as byproducts of metabolism. Creatinine, one such chemical, is released by muscle cells when they degenerate naturally as a result of wear and tear or aging.
- The kidneys eliminate creatinine from the body through urine.
- It can be detected both in blood and urine.
- A blood test can help determine the presence of excess creatinine caused by any abnormality in the body.
The normal range of creatinine levels may differ from age, sex, size, and muscle buildup of the person.
If the creatinine level rises beyond the normal range in the blood, it indicates:
- Kidney failure, both acute or chronic
- Kidney obstruction
- Kidney infection
- Urinary tract obstruction
- Very high protein consumption
- Intense exercise that has damaged the muscles
- Heart disease
- Diabetes
- High blood pressure
- Medications
Some diseases that affect the kidneys reduce the functionality of the kidneys and result in high creatinine in the blood.
How to diagnose high creatinine levels in the body
Creatine can be measured in both blood and urine in the following ways:
Blood
A blood sample is collected from a vein and sent to the lab for analysis.
The normal range of creatinine levels in the blood are:
- Males: 60 to 110 mcmol/L or 0.7 to 1.2 mg/dL.
- Females: 45 to 90 mcmol/L or 0.5 to 1.0 mg/dL.
Urine
A urine sample is collected early in the morning and sent for analysis.
The normal range of creatinine levels in urine are:
- Males: 995 to 2936 mg/24 hours.
- Females: 601 to 1689 mg/24 hours.
What are the symptoms of high creatinine levels in the blood?
A spontaneous and temporary elevation of creatinine may be caused by certain medications, intake of high amounts of proteins or red meat, or dehydration. However, persistently high creatinine levels are a serious issue that indicates kidney damage.
The symptoms of high creatinine in the body include:
- Swelling or edema
- Changes in urination
- Painful urination
- Nausea and vomiting
- Decreased appetite
- Shortness of breath
- Muscle cramps
- Chest pains
- Dehydration
- Fatigue
- Dry and itchy skin
- Puffiness around the eyes
- High blood pressure
- Confusion
- Difficulty sleeping
What is creatinine clearance?
This test determines how well the kidneys perform and how well the blood flows to them.
- Creatinine is a waste product produced by regular muscle activity as well as animal protein in the diet.
- It is removed from the blood by healthy kidneys and is then excreted from the body via urine.
Typically, the creatinine clearance test compares the creatinine level in a 24-hour urine sample to the creatinine level in the blood. This shows how well the kidneys are operating and helps the doctor determine the glomerular filtration rate (the quantity of blood cleansed per minute by glomeruli, which are microscopic filters in the kidneys).
How is a 24-hour urine creatinine test performed?
One sample for a spot urine test, ideally early in the morning, is collected.
To get a 24-hour urine sample, one must collect all the urine excreted for 24 hours.
- First thing in the morning, empty the bladder thoroughly without collecting the sample. Take note of the time.
- Then, over the following 24 hours, one should collect samples every time they go to the restroom.
- After each collection, store the urine in the refrigerator or in a cold area.
- Once finished collecting the urine for 24 hours, it may be sent to the lab for testing
What factors affect the result of the urine creatinine test?
The urine creatinine level may be greater than usual if a person is muscular, and the levels are lower than normal if a person is of petite stature or have little muscle mass due to illness.
Urine creatinine levels may vary with ethnicities. People belonging to a particular ethnicity may have slightly higher levels, which is considered normal.
Certain medications may have an impact on the findings.
How to treat high creatinine levels in the body
High creatinine levels can be caused by a variety of factors, and the symptoms may differ depending on the etiology.
- In many circumstances, drugs can help alleviate excessive creatinine levels by addressing the underlying disease.
- Drugs to treat high blood pressure may help the endothelial damage seen in the renal blood vessels in diabetes and hypertension.
- Plenty of hydration and dietary restrictions on sodium, protein, and uric acid-containing foods is a must.
Dialysis, in addition to drugs, to help filter toxins and waste products from the blood could be necessary in cases of renal failure. A kidney transplant may be required in severe or end-stage cases.
