- What to Expect with a Kidney Disease Diagnosis
- Blood Pressure Measurement
- Microalbuminuria and Proteinuria
- Glomerular Filtration Rate (GFR) Creatinine Measurement
- Blood Urea Nitrogen (BUN)
- Additional Tests for Kidney Disease
- Renal Imaging
- Renal Biopsy
- Urine Creatinine Test Normal Range + Low & High Levels
- What is Creatinine?
- Why Doctors Order It
- Is it Better to Test Creatinine in the Urine or Blood?
- Urine Test Types & Procedure
- 24h Urine Creatinine Test Procedure
- Regular (Random) Test
- 24h Creatinine
- Increasing Creatinine
- Lowering Creatinine
- Learn More
- Blood & Urine Tests
- Creatinine Test: MedlinePlus Lab Test Information
- Creatinine blood test: Purpose, procedure, and low or high ranges
- Chronic kidney disease
- Kidney obstruction
- Increased consumption of protein
- Intense exercise
- Certain medications
- Low muscle mass
- Extreme weight loss
- Lab Tests Online
- Creatinine and Creatinine Clearance Blood Tests
What to Expect with a Kidney Disease Diagnosis
Since you can have kidney disease without any symptoms, your doctor may first detect the condition through routine blood and urine tests.
The National Kidney Foundation recommends 3 simple tests to screen for kidney disease:
- Blood pressure measurement
- Spot check for protein or albumin in the urine (proteinuria)
- Calculation of glomerular filtration rate (GFR) a serum creatinine measurement
Measuring urea nitrogen in the blood provides additional information.
Blood Pressure Measurement
High blood pressure can lead to kidney disease. It can also be a sign that your kidneys are already impaired. The only way to know whether your blood pressure is high is to have a health professional measure it with a blood pressure cuff.
The result is expressed as two numbers. The top number, which is called the systolic pressure, represents the pressure when your heart is beating. The bottom number, which is called the diastolic pressure, shows the pressure when your heart is resting between beats. Your blood pressure is considered normal if it stays below 120/80 (expressed as “120 over 80”).
The National Heart, Lung, and Blood Institute (NHLBI) recommends that people with kidney disease use whatever therapy is necessary, including lifestyle changes and medicines, to keep their blood pressure below 130/80.
Microalbuminuria and Proteinuria
Healthy kidneys take wastes the blood but leave protein. Impaired kidneys may fail to separate a blood protein called albumin from the wastes. At first, only small amounts of albumin may leak into the urine, a condition known as microalbuminuria, a sign of deteriorating kidney function.
As kidney function worsens, the amount of albumin and other proteins in the urine increases, and the condition is called proteinuria. Your doctor may test for protein using a dipstick in a small sample of your urine taken in the doctor’s office. The color of the dipstick indicates the presence or absence of proteinuria.
A more sensitive test for protein or albumin in the urine involves laboratory measurement and calculation of the protein-to-creatinine or albumin-to-creatinine ratio. This test should be used to detect kidney disease in people at high risk, especially those with diabetes.
If your first laboratory test shows high levels of protein, another test should be done 1 to 2 weeks later. If the second test also shows high levels of protein, you have persistent proteinuria and should have additional tests to evaluate your kidney function.
Glomerular Filtration Rate (GFR) Creatinine Measurement
GFR is a calculation of how efficiently the kidneys are filtering wastes from the blood.
A traditional GFR calculation requires an injection into the bloodstream of a substance that is later measured in a 24-hour urine collection.
Recently, scientists found they could calculate GFR without an injection or urine collection. The new calculation requires only a measurement of the creatinine in a blood sample.
Creatinine is a waste product in the blood created by the normal breakdown of muscle cells during activity. Healthy kidneys take creatinine the blood and put it into the urine to leave the body. When kidneys are not working well, creatinine builds up in the blood.
In the lab, your blood will be tested to see how many milligrams of creatinine are in one deciliter of blood (mg/dL).
Creatinine levels in the blood can vary, and each laboratory has its own normal range, usually 0.6 to 1.2 mg/dL.
If your creatinine level is only slightly above this range, you probably will not feel sick, but the elevation is a sign that your kidneys are not working at full strength.
One formula for estimating kidney function equates a creatinine level of 1.7 mg/dL for most men and 1.4 mg/dL for most women to 50 percent of normal kidney function. But because creatinine values are so variable and can be affected by diet, a GFR calculation is more accurate for determining whether a person has reduced kidney function.
The new GFR calculation uses the patient’s creatinine measurement along with weight, age, and values assigned for sex and race. Some medical laboratories may make the GFR calculation when a creatinine value is measured and include it on their lab report.
Blood Urea Nitrogen (BUN)
Blood carries protein to cells throughout the body. After the cells use the protein, the remaining waste product is returned to the blood as urea, a compound that contains nitrogen. Healthy kidneys take urea the blood and put it in the urine. If your kidneys are not working well, the urea will stay in the blood.
A deciliter of normal blood contains 7 to 20 milligrams of urea. If your BUN is more than 20 mg/dL, your kidneys may not be working at full strength. Other possible causes of an elevated BUN include dehydration and heart failure.
Additional Tests for Kidney Disease
If blood and urine tests indicate reduced kidney function, your doctor may recommend additional tests to help identify the cause of the problem:
Methods of renal imaging (taking pictures of the kidneys) include ultrasound, computed tomography (CT scan), and magnetic resonance imaging (MRI). These tools are most helpful in finding unusual growths or blockages to the flow of urine.
Your doctor may want to see a tiny piece of your kidney tissue under a microscope. To obtain this tissue sample, the doctor will perform a renal biopsy — a hospital procedure in which the doctor inserts a needle through your skin into the back of the kidney. The needle retrieves a strand of tissue about 1/2 to 3/4 of an inch long.
For the procedure, you will lie on your stomach on a table and receive local anesthetic to numb the skin. The sample tissue will help the doctor identify problems at the cellular level.
The above information is from the National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC), a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
The NIDDK is part of the National Institutes of Health of the U.S. Department of Health and Human Services.
Publications produced by the Clearinghouse are carefully reviewed by both NIDDK scientists and outside experts.
Urine Creatinine Test Normal Range + Low & High Levels
The urine creatinine test can reveal a lot about the health of your kidneys. If you have kidney disease, your levels will be low. On the other hand, exercising often, being muscular, and eating a meat-heavy diet can increase creatinine. Read on to understand how this test works and how to interpret your results.
What is Creatinine?
Creatinine is a waste product created from the normal wear and tear of muscles. It is produced from creatine, a protein needed to generate the energy for muscle contractions [1, 2].
Its production essentially reflects lean body mass, and because this mass changes little from day to day, the production rate is fairly constant. Women, children, and older people tend to have lower levels of creatinine compared to adult men because they have less muscle mass .
Creatinine is removed from the body by the kidneys, which filter almost all of it from the blood into the urine. Thus, urine creatinine levels can be used as a measure of kidney health [3, 1, 4].
If kidney function is impaired, creatinine levels in urine decrease.
Why Doctors Order It
Doctors can order a urine creatinine test to :
- Check whether your kidneys are working well
- Check if a treatment for kidney disease is working
- Adjust the urinary levels of other markers, such as metabolites or toxins
Is it Better to Test Creatinine in the Urine or Blood?
While blood creatinine is more reliable, changes in urine creatinine happen faster. That’s why it can be used to monitor kidney disease development and recovery .
Urine Test Types & Procedure
There are two main types of urine creatinine tests:
- Random (spot) urine test, which is when you collect a urine sample at a random time in the day and bring it to the lab for analysis
- 24h creatinine test, which involves storing your urine into a special container over a full 24-hour period before bringing it to the lab
24h creatinine is preferred to random (spot) creatinine because it’s more accurate. However, it’s also more demanding and requires you to carefully store your urine over a 24 hour period .
24h Urine Creatinine Test Procedure
For the 24h test, you will initially get one or more containers for collecting and storing your urine.
You’ll only need to skip collecting your first morning urine – for example, at 9 AM. Flush this urine and note the time. That’s when your “timer” starts. Alternatively, your doctor may specify the exact time you should start collecting.
Collect the next urine into the container. Keep your container in a cold place such as the refrigerator or in a cooler on ice.
Keep collecting all your urine over the next 24 hours. In our scenario, that would be when you urinate around 8.40-9 AM the next day. The goal is to try to urinate as close as possible to the end of the 24 hour window. If you could urinate at 8.59, that would be ideal. If not, that’s still ok.
Do not collect urine after 24 hours are up! Following our example, if you collected urine at 10.10 AM, your results would be off.
Once you have collected your 24h urine, bring it to the lab for analysis as soon as possible.
It’s important to collect all urine within this time frame. If anything went wrong – you forgot to collect urine at any point, you spilled some, or you didn’t keep it in a cold place – let your doctor know. Otherwise, you risk getting inaccurate results.
Regular (Random) Test
Urine creatinine test results are usually reported in mg/dL (milligrams per deciliter).
The normal range is around 20 – 275 mg/dL in women and 20 – 320 mg/dL in men. Ranges may vary between laboratories.
Results of the 24h creatinine test are typically reported in g/24h (grams of creatinine in the urine over 24 hours).
The normal range is 0.5-2.15 g/24h. Ranges may again vary slightly between laboratories doing the testing.
Causes shown here have been associated with low creatinine levels. Work with your doctor or another health care professional to get an accurate diagnosis. Your doctor will interpret your value, taking into account your medical history, symptoms, and other test results.
Low urine creatinine levels can be caused by
- Kidney damage and disease [7, 8]
- Overhydration (when your urine is very diluted) 
- Muscle wasting (in illness or aging) [9, 10, 5, 11]
- Diabetes 
Some drugs can also decrease urine creatinine levels :
- Antibiotics such as trimethoprim/sulfamethoxazole (Bactrim, Cotrim, Septra)
- Histamine H2 receptor blockers that inhibit stomach acid production: cimetidine (Tagamet), famotidine (Pepcid), and ranitidine (Zantac) 
- NSAIDs such as indomethacin (Indocid, Indocin) and ibuprofen [12, 13]
- Acetaminophen (Tylenol, Panadol, paracetamol) 
The most important thing is to work with your doctor to find out what’s causing your low urine creatinine and to treat any underlying conditions.
If you are suffering from kidney disease, you may need to lower your protein intake and increase dietary fiber. Kidneys must work harder when there’s more protein in the diet, which can worsen their function. On the other hand, fiber-rich foods fruits, veggies, whole grains, and legumes improve kidney health [15, 16].
Read this post about the renal diet to find out which foods to eat and avoid if you have kidney disease.
The most important thing is to work with your doctor to find out what’s causing your high urine creatinine and to treat any underlying conditions.
In addition, make sure you are well hydrated as you are taking the test and in general .
The following markers are also used to check kidney health:
Blood & Urine Tests
Testing your blood and urine can let you and your healthcare team see how your body is working. Tracking your test results over time can show you how your kidneys are doing. Here are some common tests that are done when you have CKD:
|Serum CreatinineCreatinine (cree-A-ti-neen) is a waste you make each time you move a muscle. Those with more muscle make more creatinine. Healthy kidneys remove creatinine from your blood. This means that a high serum (blood) level may be due to kidney damage. If your level is high, your doctor should recheck it. If two or more levels are high, you may have kidney disease.||The normal serum creatinine range is 0.6–1.1 mg/dL in women and 0.7–1.3 mg/dL in men.|
|Creatinine ClearanceThis test compares creatinine in your blood and urine. The difference shows how well your kidneys work. You may need to collect your urine for 24 hours in a jug.||Normal creatinine clearance is 88–128 mL/min for healthy women and 97–137 mL/min for healthy men.|
|Glomerular Filtration Rate (GFR)GFR is a formula that uses your creatinine, age, race, and sex. GFR is used to divide chronic kidney disease into five stages. The result is about the same as your percent kidney function. So, a GFR of 60 means you may have function that is 60% of normal.You can use our egfr calculator to test your gfr!||Healthy adults have a GFR of about 140*; normal is greater than 90. Children and seniors tend to have lower GFRs. A GFR less than 15 is kidney failure.*GFR is reported in mL/min/1.73 m2.|
|Urine AlbuminHealthy kidneys have filters (nephrons). These remove wastes but keep in large cells, red blood cells and proteins. Albumin is one type of protein. When the filters are damaged, they may leak protein into your urine. Albumin levels can go up if you exercise a lot or have high blood sugar, too. Bladder infections can also make the levels go up.||A normal level is from 0 to about 8 mg/dL.Rising levels in the urine can show a kidney problem. It is vital to know if your urine has protein in it!|
|Urine MicroalbuminDamaged kidneys can leak microscopic amounts of protein. These are too small to be found with standard tests—but can be an early warning sign. Special dipsticks or tests can find the protein. If you have diabetes, you are at a higher risk for kidney disease. Have a urine test for microalbumin at least once a year.||Less that 30 mg is normal. 30–300 mg may mean early CKD. More than 300 mg may mean a later stage of CKD.|
|Albumin to Creatinine Ratio.Urine protein divided by creatinine gives a good sense of how much protein may leak your kidneys in a day. This test is not changed by how much water is in your urine.||A normal level is less that 30 mg per gram.|
|Blood Urea Nitrogen (BUN)BUN is a measure of a waste (urea) in the blood. Your body makes urea when it breaks down protein. A low BUN may mean you are not eating enough protein. A high BUN may mean kidney function that is less than normal. Other factors may affect a BUN, too. Bleeding in the gut, heart failure, and some medicines may cause the BUN to go up. As BUN rises, you may have symptoms of kidney disease, such as a bad taste in your mouth, poor appetite, nausea, and vomiting.||The normal BUN level for healthy adults (and children) is 7–20 mg/dL.|
|Hematocrit (Hct)Hct is the percent of blood that is made up of red blood cells. This test can be used to check for anemia.||The normal Hct level is 36–44% for healthy women and 40–50% for healthy men.|
|Hemoglobin (Hgb)Hgb is the iron protein that carries oxygen and gives red blood cells their red color. Hgb is also used to test for anemia.||The normal Hgb level is 12–16 g/dL for healthy women and 14–18 g/dL for healthy men.|
|Hemoglobin A1c (HbA1c)HbA1c is a 3-month average of your blood sugar level. If you have diabetes, have your HbA1c tested at least every 6 months.||Your doctor will tell you what your goal should be. It will be between 6.5% and 8%, your health and age.|
|GlucoseGlucose is a sugar. Your blood sugar level is tested to see if your body can use sugar in a normal way. High levels are most often found in people with diabetes. Some medicines can also raise blood glucose levels. If your fasting blood glucose level is higher than 126 mg/dL, you have diabetes.||Normal (fasting) glucose levels are less than 100 mg/dL.In those with diabetes, the goal before eating is 80–130 mg/dL. After eating, the goal is less than 180 mg/dL.|
As you can see, there is a big job for you as someone with CKD:
- You can ask questions of your healthcare team.
- You can track your lab test results.
- You are the only one who can pay attention to how you feel.
- You are the only one who can take your medicines, follow a meal plan, and report your symptoms.
There is a lot you can do to try to slow your CKD and feel your best. The more you know, the better you can help yourself.
Work with Your Doctor
Life Options is administered by the Medical Education Institute, Inc., of Madison, Wis.
Copyright ©1993-2020 Life Options and Medical Education Institute, Inc.
Updated February 29, 2020.
Creatinine Test: MedlinePlus Lab Test Information
URL of this page: https://medlineplus.gov/lab-tests/creatinine-test/
This test measures creatinine levels in blood and/or urine. Creatinine is a waste product made by your muscles as part of regular, everyday activity.
Normally, your kidneys filter creatinine from your blood and send it the body in your urine. If there is a problem with your kidneys, creatinine can build up in the blood and less will be released in urine.
If blood and/or urine creatinine levels are not normal, it can be a sign of kidney disease.
Other names: blood creatinine, serum creatinine, urine creatinine
A creatinine test is used to see if your kidneys are working normally. It's often ordered along with another kidney test called blood urea nitrogen (BUN) or as part of a comprehensive metabolic panel (CMP). A CMP is a group of tests that provide information about different organs and systems in the body. A CMP is frequently included in a routine checkup.
You may need this test if you have symptoms of kidney disease. These include:
- Puffiness around the eyes
- Swelling in your feet and/or ankles
- Decreased appetite
- Frequent and painful urination
- Urine that is foamy or bloody
You may also need this test if you have certain risk factors for kidney disease. You may be at higher risk for kidney disease if you have:
Creatinine can be tested in blood or urine.
For a creatinine blood test:
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
For a creatinine urine test:
Your health care provider will ask you to collect all urine during a 24-hour period. Your health care provider or a laboratory professional will give you a container to collect your urine and instructions on how to collect and store your samples. A 24-hour urine sample test generally includes the following steps:
- Empty your bladder in the morning and flush that urine away. Record the time.
- For the next 24 hours, save all your urine passed in the container provided.
- Store your urine container in the refrigerator or a cooler with ice.
- Return the sample container to your health provider's office or the laboratory as instructed.
You may be told to not eat cooked meat for 24 hours before your test. Studies have shown that cooked meat can temporarily raise creatinine levels.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
There is no risk to having a urine test.
In general, high levels of creatinine in blood and low levels in urine indicate kidney disease or another condition that affects kidney function. These include:
But abnormal results don't always mean kidney disease. The following conditions can temporarily raise creatinine levels:
- Intense exercise
- A diet high in red meat
- Certain medicines. Some medicines have side effects that raise creatinine levels.
If you have questions about your results, talk to your health care provider.
Your health care provider may also order a creatinine clearance test. A creatinine clearance test compares the level of creatinine in blood with the level of creatinine in urine. A creatinine clearance test may provide more accurate information on kidney function than a blood or urine test alone.
- Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Creatinine, Serum; p. 198.
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Creatinine blood test: Purpose, procedure, and low or high ranges
The creatinine blood test measures the level of creatinine in the blood. The result of this blood test is useful, as it is an important marker of how well the kidneys are working.
Creatinine is the waste product of creatine, which the muscles use to make energy. Typically, creatinine travels in the blood to the kidneys where it leaves the body in the urine. High levels in the blood might indicate that the kidneys are not working correctly.
The creatinine blood test helps doctors to diagnose kidney disease. A poorly functioning kidney cannot filter creatinine as well as it usually does, which causes levels in the blood to rise.
A doctor or a healthcare professional will carry out the blood test.
Before the test, they might ask questions related to:
- physical activity
- any supplements
- current medications
It is best to discuss any medical conditions and any family history of kidney disease at the time of the blood test.
There is no need to avoid food or drink before the blood test.
The blood test involves collecting blood from a vein in the arm or hand. The doctor then sends the sample to a lab for analysis.
The kidneys are responsible for keeping the level of creatinine in the blood within a normal range.
The typical reference range for serum creatinine is 60 to 110 micromoles per liter (μmol/L) (0.7 to 1.2 milligrams per deciliter (mg/dL)) for men and 45 to 90 μmol/L (0.5 to 1.0 mg/dL) for women.
Some of the causes of high creatinine levels are:
Chronic kidney disease
When kidneys are damaged, they have trouble removing creatinine from the blood and levels rise.
Doctors use the result of the creatinine blood test to calculate GFR, which is a more specific measure that can indicate chronic kidney disease.
A GFR of 60 or over is considered normal, a GFR less than 60 may indicate kidney disease. A level of 15 or less is defined medically as kidney failure.
A blockage in the flow of urine, such as an enlarged prostate or kidney stone, could cause kidney obstruction. This blockage can create a backup of urine into the kidney and impair the kidney’s ability to function correctly, which might raise the level of creatinine. The medical term for this condition is hydronephrosis.
Severe dehydration is a risk factor for kidney injury, which will affect creatinine levels.
Increased consumption of protein
What a person eats can have a significant impact on creatinine levels. For example, proteins and cooked meat contain creatinine, so eating more than the recommended amount of meat or other proteins for your activity levels, or adding extra protein to the diet through supplements can cause high creatinine levels.
Creatine is present in the muscles and helps them produce energy. Rigorous exercise can increase creatinine levels by increasing muscle breakdown.
Antibiotics, such as trimethoprim, and H2 blockers, such as cimetidine, can cause a temporary increase in measured serum creatinine levels.
Creatinine levels may be lower than normal for the following reasons:
Low muscle mass
Share on PinterestIncreased urine production during pregnancy can cause low creatinine levels.
Because the breakdown of muscle produces creatinine, low muscle mass can result in low levels of creatinine.
Older people are more at risk as muscle mass declines with age. Malnutrition can also cause low muscle mass and low creatinine levels.
Chronic conditions, such as myasthenia gravis or muscular dystrophy, may result in low creatinine levels.
Pregnancy causes an increase in blood flow to the kidney leading to increased urine production and faster elimination of creatinine, leading to lower levels.
Extreme weight loss
Weight loss can result in the reduction of muscle mass, leading to low levels of creatinine.
Dietary choices and physical activity play an essential role in regulating blood creatinine levels. It is advisable to keep protein consumption within the recommended range for age and activity level.
Talk to a doctor about the treatment options, especially if the level of creatinine in the blood is high. If it persists at a high level, people may need to see a kidney specialist. Early treatment of rising creatinine levels is essential to prevent more significant kidney disease.
Lab Tests Online
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Physician's Reference Laboratory: Kidney Function Panel. Available online at http://www.prlnet.com/Kidney.htm.
Creatinine and Creatinine Clearance Blood Tests
Creatinine is a waste product from the normal breakdown of muscle tissue. As creatinine is produced, it's filtered through the kidneys and excreted in urine.
Doctors measure the blood creatinine level as a test of kidney function.
The kidneys' ability to handle creatinine is called the creatinine clearance rate, which helps to estimate the glomerular filtration rate (GFR) — the rate of blood flow through the kidneys.
All the blood in the body flows through the kidneys hundreds of times each day. The kidneys push the liquid part of blood through tiny filters (called nephrons), then reabsorb most of the fluid back into the blood. The fluid and waste products that the kidneys don't reabsorb are excreted as urine.
The rate of blood flow through the kidneys is the glomerular filtration rate, or GFR. (The glomeruli are microscopic bundles of blood vessels inside nephrons, and are crucial parts of the filtering system.) The glomerular filtration rate can't be measured directly — that's where measuring creatinine and creatinine clearance comes in.
Creatinine is a waste product that is produced continuously during normal muscle breakdown. The kidneys filter creatinine from the blood into the urine, and reabsorb almost none of it.
The amount of blood the kidneys can make creatinine-free each minute is called the creatinine clearance. Creatinine clearance in a healthy young person is about 95 milliliters per minute for women/120 milliliters per minute for men.
This means that each minute, that person's kidneys clear 95-120 mL of blood free of creatinine. The GFR can vary depending on age, sex, and size.
Generally, the creatinine clearance is a good estimation of the glomerular filtration rate.
Doctors use creatinine and creatinine clearance tests to check renal function (kidney function). Testing the rate of creatinine clearance shows the kidneys' ability to filter the blood. As renal function declines, creatinine clearance also goes down.
There are two main ways doctors use creatinine tests to measure kidney function:
- Creatinine clearance can be precisely determined by measuring the amount of creatinine present in a sample of urine collected over 24 hours. This method requires a person to place all his urine in a plastic jug for one day, then bring it in for testing. Although the urine creatinine measurement method is inconvenient, it may be necessary to diagnose some kidney conditions.
- GFR can be estimated using a single blood level of creatinine, which your doctor enters into a formula. Different formulas are available, which take into account age, sex, and sometimes weight and ethnicity. The higher the blood creatinine level, the lower the estimated GFR and creatinine clearance.
For practical reasons, the blood test estimation method for GFR is used far more often than the 24-hour urine collection test for creatinine clearance. However, the use of 24-hour collections for creatinine clearance may still be useful in patients who have large muscle mass or a marked decrease in muscle mass.
A low GFR or creatinine clearance demonstrates kidney disease. The decline in kidney function can be either acute (sudden, often reversible) or chronic (long-term and irreversible). Repeated GFR or creatinine clearance measurements over time can identify kidney disease as acute or chronic.
Kidney function and creatinine clearance naturally decline with age. Fortunately, the kidneys have a huge reserve capacity. Most people can lose 30 to 40 percent of their renal function without having significant problems.
Doctors determine the severity of chronic kidney disease with a staging system that uses GFR:
Stage 1: GFR 90 or greater (normal kidney function)
Stage 2: GFR 60-89 (mild decline in kidney function)
Stage 3a: GFR 45 – 59 (mild to moderate decline in kidney function)
Stage 3b GFR 30 – 44 (moderate to severe decline in kidney function)
Stage 4: GFR 15-29 (severe decline in kidney function)
Stage 5: GFR less than 15 (kidney failure, usually requiring dialysis)
People over age 60 may have an apparently normal creatinine blood level, but still have a low GFR and creatinine clearance. The 24-hour urine collection method, or one of the GFR estimation formulas, can more accurately identify the decline in kidney function.
If you have a low GFR or creatinine clearance, your doctor will design an action plan with you to address the problem.
The main causes of chronic kidney disease are high blood pressure and diabetes. If you have these conditions, the first step is to get them under control with improved diet, exercise, and medications. If these conditions are not present, further testing may be needed to identify the cause of kidney disease.
Periodically checking the GFR or creatinine clearance allows you and your doctor to follow any decline in kidney function over time. Your doctor may need to make changes in your medications to adjust for any decline in renal function.
Because over-the-counter medications (especially medications for mild aches, pains and headaches), herbs and supplements can all affect your kidneys, do not take any of these without first discussing with your doctor.
Most people do not need dialysis until GFR and creatinine clearance fall very low. However, because kidney function naturally declines with age, it's important to take action early to preserve all the kidney function you can.
Brenner, B. Brenner & Rector's The Kidney, 8th Edition, Saunders Elsevier, 2007.
National Kidney Foundation web site: “Chronic Kidney Disease.”
National Kidney Foundation web site: “Key Points: Living With Stage 4 Kidney Disease.”
Johns Hopkins Medicine web site: “Health Library: 24-Hour Urine Collection.”
Family Practice Notebook web site: “Creatinine Clearance.”
UpToDate.com literature review: “Reciprocal serum creatinine concentration and chronic kidney disease” and “Definition and staging of chronic kidney disease in adults.”
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