Normal Kidney Function Test Value

Kidneys play a vital role in excluding metabolic wastes from the body and in maintaining the overall water and electrolyte balance of the body.

 

If your physician thinks that your kidneys are not working properly, you should perform kidney function tests. These are simple urine and blood tests that can determine problems with your kidneys.

 

You may also have to do kidney function testing if you have other health issues or conditions which can harm your kidneys, such as high blood pressure or diabetes . They may help doctors to monitor these issues.

 

In this article, we will discuss various tests that are done to detect a kidney disorder. Normal kidney function test value varies for each test.

What are kidney function tests?

The kidney function tests (KFT) may help you to determine whether your kidneys are working effectively or not by examining how efficiently your kidneys are excreting wastes from your body. A blood test or a 24-hour urine sample, or both can be required for the evaluation of kidney function.

 

What types of tests are done to check kidney function?

To check the functioning of your kidney, doctors will recommend tests that can determine your glomerular filtration rate (GFR). Your glomerular filtration rate helps your doctor to estimate how fast your kidneys are removing wastes from your body.

 

 Urine tests

Urine tests generally require a small urine sample or all the urine which a person produces in a period of 24-hour.

 

Urinalysis

Urinalysis is a vast urine test which helps doctors to identify various underlying issues or estimate which test to do next. Urinalysis can help determine many undesirable particles present in the urine, like:

• bacteria

• blood

• pus

• sugar

• protein

 

Normal test value of urinalysis

If blood, pus, protein or other particles are not present in urine, this means a person does not have kidney disorder.

 

If the test shows positive results for one or more of above undesirable particles, this indicates an underlying condition, such as:

 

• kidney or bladder infections

• kidney stones

• diabetes

• kidney disease

 

Urine albumin-to-creatinine ratio (UACR) or Microalbuminuria tests

Albumin is a protein that is present in blood. Sometimes kidneys filter too much albumin in urine, it determines that kidneys are not performing their job perfectly.

 

The UACR test measures the amount of albumin and compares it to the amount of creatinine. This test tells your doctor how much amount of albumin passes into your urine in 24-hours.

 

Normal test value of UACR

• A result of 30 milligram per gram (mg/g) or even less is considered normal.

• The result which is higher than 30(mg/g) higher is a sign of kidney disease.

Microalbuminuria is a more sensitive test that can indicate tiny amounts of the albumin in the urine.

 

Individuals who are at greater risk for kidney disease generally need to take a microalbuminuria test even if urinalysis and UACR come back negative.

 

Creatinine clearance test

Creatine is a waste product in our body which supplies energy to our muscles.

 

A creatinine clearance test includes both a urine and blood test. This involves gathering all the urine a person produces in 24 hours, and taking small blood samples.

 

Doctors relate the amount of creatine in the urine to the amount of creatine in the blood. This comparison indicates the amount of waste the kidneys are filtering out, this can tell doctors about overall health.

 

Blood tests

To perform blood tests, a nurse or a doctor will insert a needle into the arm of a person to draw a blood sample. The person usually needs to perform a test first in the morning or fast before the test.

 

Serum creatinine test

A serum creatinine blood test determines the amount of creatinine present in your blood. If your kidneys are not working properly, your levels of serum creatinine goes up. Normal levels will depend on your age, sex, and the amount of your body muscle mass.

 

Normal test value for serum creatinine test:

• For women, creatinine level below 1.2 and for men below 1.4 is considered normal.

• If in women, creatinine level is above 1.2 and above 1.4 in men, then this is a signthat your kidneys are not working properly.

 

If your test results are higher than normal, then your doctor may want to perform other tests.

Glomerular filtration rate (GFR)

GFR measures how efficiently your kidneys are removing toxins, wastes, and extra fluids from your blood. Your sex, age and serum creatinine level are used to determine your GFR number. If your glomerular filtration rate is low, that means your kidneys are not working properly. As your stage of kidney disease progresses, your glomerular filtration rate also goes down.

 

Normal test value for GFR

• A GFR level of 60 or above along with normal urine albumin test is considered normal. If you have a GFRlevel of 60 or above you may have no kidney disease.

 

• A GFR level below 60 indicates a kidney related issue. You should talk to your doctor about the besttreatment options for you.

 

• A GFR number below 15 means that you have kidney failure. You will need kidney transplant or dialysis.

 

• If your GFR number is below20 constantly for 6-12 months, then your doctor will recommend you a kidney transplant.

 

Blood urea nitrogen (BUN) test

The blood urea nitrogen (BUN) test checks other waste products in blood, like urea nitrogen.

 

Urea nitrogen is a waste product and occurs as protein in our body, and the kidney removes it from blood. High levels of urea nitrogen in your blood indicates that your kidney is not filtering waste materials efficiently.

 

Normal test value of BUN

• A normal BUN level ranges from 7-20 milligrams per deciliter.

• Higher BUN levels indicatethat you have an underlying health condition affecting your kidneys.

 

Many other things affect BUN levels, like antibiotics and medications. A diet rich in proteins also affects BUN levels.

 

Doctors will generally compare BUN results with the results of a creatinine test to better understand how effectively your kidneys are filtering this waste.

 

CBC

CBC is a complete count of red blood cells, white blood cells, and platelets of a person.

 

Normal test value of CBC

• LowLevels of CBC indicates that your kidney function is reduced.

 

Other Tests

 

Imaging tests

Imaging tests generally help doctors to identify physical changes to kidneys, like kidney stones or injuries.

 

Ultrasounds

Ultrasound tests generally use safe sound waves to take photos or pictures. Doctors order an ultrasound to see changes in the position and shape of the kidneys. They also require an ultrasound to check for blockages or tumors, such as kidney stones.

 

CT scans

A computerized tomography (CT) scan uses a series of X-ray images taken from various angles around your kidneys to create a more detailed, 3D picture of your kidney. CT scan provide more in-depth information than plain X-rays.

 

It helps to determine any deformations and structural changes in your kidney. It also examines tumors, obstructive conditions, like congenital anomalies, kidney stones, and accumulation of fluid around your kidneys.

 

Normal result of CT scan

• Results are considered normal, if the kidney and kidney structures being examined are normal in appearance.

 

Biopsies

Sometimes, doctors want to perform a kidney biopsy. In this process, physicians insert a small needle into the kidney to remove kidney tissues.  Then doctors send these tissues to a specially trained doctor (pathologist) or laboratory for testing.

 

Doctors perform biopsy to detect kidney disease and to see response to your kidney to treatment.

 

Normal results of kidney Biopsies

• A normal result is when the kidneyshows normal structure.

• A resultis considered abnormal, when there are changes in kidney tissues.

 

Blood Pressure

High blood pressure is a cause of kidney disease and kidney failure. Your doctor advises you to maintain your blood pressure. You should maintain your blood sugar, high blood pressure, and cholesterol levels, if you have chronic kidney disorder or CKD.

 

What is the most accurate test for kidney function?

CDK can be evaluated by two simple tests:

 

• Blood test called glomerular filtrationrate (GFR)

• A urine test known as urine albumin-creatinine ratio (uACR)

Both of these tests are most accurate to determine the functioning of the kidney.

 

How are kidney function tests performed?

Kidney function tests generally require a blood test and a 24-hour urine sample.

 

24-hour urine sample

A 24-hour urine sample includes a creatinine clearance test. It gives your physician information about the amount of creatinine your body removes in a single day.

 

On the day of the test, urinate into the toilet as usual.

 

For the whole day and night, urinate into a specific container that is provided by your physician. Keep the container covered or capped and refrigerated during the whole collection process. Ensure to label the container properly and to tell your family members why the container is in the refrigerator.

 

On the second day morning, again urinate into the container when you wake up. This completes the 24-hour collection process.

 

Follow the instructions of your doctor about where to return the sample. You may need to return it to a lab or your doctor’s office .

 

Blood samples

Serum creatinine and BUN tests require blood samples that are taken in your doctor’s office or a lab.

 

The technician who draws the blood firstly asks the patient to form a fist so that veins stand out. Then the technician cleaned the area over the vein. They enter the needle through your skin into the vein. The blood sample will flow back into the test tube. Then the blood sample will be sent for examination.

 

You generally feel a sharp prick or pinch when a needle enters your arm. The technician places clean gauze or a dry cotton to the test site. The site around the puncture usually develops a scratch over the next few days. However, you should not feel extreme or long-term pain.

 

Treatment of early kidney disease

Your doctor will work on controlling the cause if the results of tests show early renal disease. Your doctor will also give you medications to control BP if the tests show hypertension. Apart from treatment your doctor will also recommend you to change your diet and lifestyle.

 

The main treatments of kidney diseases are:

 

• Lifestyle changes help you to remain healthy as possible

• Medicines to controls underlying conditions like high cholesterol, blood sugar level, high blood pressure

• Dialysis

• Kidney transplant

 

You should visit your healthcare provider on a regular basis to observe your condition.

 

Summary

Kidney plays an essential role in excreting waste products from our body. Kidney disease occurs due to some underlying conditions, like high blood pressure, high cholesterol, and high blood sugar levels. There are various tests to detect a kidney disorder. Normal kidney function test value varies for each test. Kidney disorders can be prevented by many treatment options like medications and changing in life-style.