Renal Function Test
About Renal Function Test
A renal function test – also called a kidney function test – is a blood and urine test that measures how well the kidneys function in our body. The renal function test measures the presence of proteins and urea nitrogen in the blood and the presence of proteins, blood, or other bacterial infections in urine. Healthcare providers use this test to screen your risk of kidney damage due to other health conditions like diabetes and hypertension.
Functions of Kidneys
- Filter waste material
- Regulate fluid levels in the body
- Regulate blood pressure
- Regulate salt concentration
- Produce hormones that work on blood and bones
A renal function test is done to detect the signs of kidney damage. High levels of protein in the blood are the usual signs of kidney disease. Other conditions that affect the functioning of the kidney are diabetes, high blood pressure (hypertension), blood in the urine, pain during urination, and frequent urination.
What is the Renal Function test used for?
Diagnose kidney disease
Determine risks associated with diabetes
Determine risks associated with hypertension
Diagnose other chronic kidney diseases
What are the tests included in renal function test?
A renal function test is used to analyse proteins and waste products in blood and urine samples. This includes:
Estimated Glomerular Filtration Rate (eGFR):
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This test measures the filtration rate of kidneys based on protein levels, age, gender, height, weight, and race.
Serum creatinine:
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Creatinine is the waste product that is filtered from the blood by the kidney. When the level of creatinine increases in the blood it is a sign of kidney disease.
Blood urea nitrogen (BUN):
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Urea nitrogen is a waste product formed after the breakdown of proteins and excreted out of the body through urine. A normal urea nitrogen level depends on age and other health conditions; high levels may indicate kidney disease.
Microalbuminuria:
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This test measures the presence of albumin protein in the urine. This test detects the risk of developing kidney disease because of diabetes or high blood pressure.
Albumin-Creatinine Ratio:
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This test measures the presence of albumin and creatinine in urine and detects kidney damage.
Creatinine clearance:
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This test measures the level of creatinine in the urine to that of the blood. A urine sample is collected for 24 hours to measure creatinine clearance levels.
Urinalysis:
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This test includes microscopic analysis of urine sample to detect color, appearance, pH, and other chemical and microscopic findings that monitor disorders of the kidney, urinary tract infections, and diabetes.
Who should get tested?
A renal function test is recommended to diagnose and treat disorders that affect the functioning of the kidneys. Other health conditions like diabetes and blood pressure also affect the kidneys
Renal function test can be recommended for individuals who are/have:
Age over 60 years and above
Abnormal kidney structure
Family history of kidney disease
High blood pressure
Overweight or obese
Use of medications that damage the kidney
Smoke cigarettes
Other heart/ cardiovascular diseases
Test preparation
The blood sample is collected at the lab for testing. A 24-hour urine test is performed where the urine sample is collected for 24 hours by the patient in the container provided. The patient is advised to urinate for the first time normally as they wake up and later collect the urine sample in the container for the rest of the day, and also urinate in the container after waking up the next morning.
Interpretation of results
Parameters |
Normal levels |
| Estimated GFR (eGFR) | Greater than 90 mL/min/1.73 m2 |
| Serum creatinine | 0.6–1.1 mg/dL in women and 0.7–1.3 mg/dL in men |
| Blood urea nitrogen (BUN) | 7–20 mg/dL |
| Microalbuminuria | Less than 30 mg |
| Albumin-Creatinine Ratio | Less than 30 mg per gram. |
| Creatinine clearance | 88–128 mL/min – healthy women 97–137 mL/min – healthy men. |
| Urinalysis | |
| Parameters | Normal values |
| Color | Colorless to yellow color |
| Appearance | Clear or translucent |
| pH | 4.5-5.5 |
| Microscopic examination | Negative |
| Dipstick test | Negative |
| Urine culture | Negative |
Deviation from normal levels indicates the following:
- The eGFR range below 60 can indicate different stages of kidney functionality and damage.
- Having higher-than-normal of serum creatinine and BUN levels in the blood increases the risk of kidney disease.
- Having higher-than-normal levels of urine albumin and albumin-creatinine ratio can increase the risk of kidney disease and other disorders like diabetes and high blood pressure.
- Having dark or amber-colored urine is usually a sign of kidney disease.
- High or low pH levels of the urine are an indication of urinary tract infections.
- The presence of crystals in the urine can be an indication of kidney stones.
- The presence of blood in urine can indicate infection, and protein indicates kidney disease.
- The presence of bacteria, red blood cells, or white blood cells in the urine indicates urinary tract infections and other kidney diseases.
FAQs
What is the turnaround time (TAT) for the results of a renal function test?
Test results for a renal function test are usually available after 1-2 working days, although it could take longer at times
What are the risks associated with a renal function test?
This test is simple and involves negligible risk. After the blood test, you might experience slight bruising, dizziness, or fatigue.
Can any factors influence the accuracy of the renal function test?
Certain lifestyle conditions such as a high protein diet, intense exercise, and certain medications can increase creatinine levels.Other than these, certain disease conditions can also vary the accuracy of the result.
What should you do if you have an abnormal renal function test result?
An abnormal renal function test can mean lower levels of eGFR and BUN that indicate kidney disease and other health conditions like malnutrition, severe muscle and weight loss, and chronic illnesses. However, based on your age, family history, medical history, and the medications you use, your healthcare provider may decide a suitable treatment plan.
Higher levels of serum creatinine and BUN levels are associated with kidney disease and other health conditions like muscle disease, diabetes, dehydration, heart problems, overactive thyroid glands, etc
What precautions can be taken to maintain normal levels of different parameters of renal function test?
Lifestyle changes that include reducing red meat, increasing intake of lean protein, staying hydrated, eating more fiber, etc., can be some precautionary measures to maintain normal levels and proper functioning of kidneys.
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