Lesser-Known Facts about Kidney Function Tests

Everyone has two kidneys located above below rib cage and above abdomen on both sides of spinal cord. They are just of your fist size but play a bigger role for proper maintenance of health. The key role of kidneys is to excrete waste from human physique as urine. It assists in regulating the level of essential minerals and water in body.

Also, they promote the production of Vitamin D, RBCs (red blood cells and blood pressure regulating hormones as well. kidney function test is suggested when proper function of kidneys is suspicious. Urine and blood tests identifies kidney-related issues.

Kidney function test should be also done if any health issue can affect the health of kidneys like high blood pressure and diabetes. This will let the doctors to administer treatment accordingly to control such issues.

Kidney problems and its symptoms

Kidney issue-related symptoms are mentioned below:

  • Feet and hand swelling due to accumulation of bodily fluids
  • Painful urination
  • Difficulty beginning peeing
  • Frequent urination urges
  • Blood traces in urine
  • HBD (High Blood Pressure)

Any of the aforesaid symptoms never means there is something serious regarding your kidney health unless some have occurred simultaneously. Then, you should be serious about your kidney function as there can be something wrong. Only kidney function tests assist in the determination of the actual reason (or problem).

Kidney function test types

For kidney function test, a test set will be ordered by your private doctor for the determination of GFR (glomerular filtration rate). It assists the doctor to know the rate at which your kidneys clear waste from the body 


Urinalysis is done for tracing the presence of blood and protein in urine. Innumerable causes are there which result in presence of protein in urine other than kidney disease. Any infection raises the protein traces in the urine which is why strenuous physical activity is important. After a couple of weeks, test has to be done again for comparing the reports (before and after).

You might be asked to give 24 hours urine sample collection as well to assess the rate at which creatinine (muscle tissue’s breakdown product) is removed from the body

Serum creatinine test

Blood test helps in detection if creatinine gets deposited in blood or not! As kidney excretes creatinine completely from blood, a higher level is a matter of concern. As per NKF (National Kidney Foundation) a high level of creatinine than 1.4 mg/dL in men and 1.2 mg/dL in women is a serious threat to kidney issue.

Blood urea nitrogen (BUN)

BUN (blood urea nitrogen) test looks for the accumulation of waste in blood. It measures the level of nitrogen in blood. Breakdown of protein evolves many products and urea nitrogen is one of them.

But several reasons can be there for elevated BUN and some of them are consumption of antibiotics, large dose of aspirin and other medications. If you are taking any at present, inform it to your doctor as you might have to stop taking them a couple of days ahead the test. 7-20 mg/dL is the normal range of BUN. Any measurement below or higher is threatening to the health.

Estimated GFR

It determines how perfectly kidneys are working in filtering the waste. It finds out the rate on the basis of the aspects like;

  • Weight
  • Height
  • Race
  • Gender
  • Age
  • Test report (creatinine levels)

Report stating low GFR than 60ml/min or 1.73m2 will be regarded as the initial emergence of kidney problems. 

How tests are conducted?

Blood test and 24 hours urine sample is needed to carry out the kidney function test.

24 hours urine sample

Creatinine clearance test needs 24 hours urine sample. It will let the doctor to have an idea the expelling amount of creatinine from the body in a day.

On your test day, urinate normally but not in toilet. You must urinate in the specific container given by the doctor. Cap the container tightly and put it into the fridge. Just put a label on it so that anyone doesn’t get confused with it.

Next day morning collect the urine sample in the container again to complete 24 hours cycle. Drop it off in the place (doctor’s clinic or lab) as per doctor’s instructions.

Blood samples

Serum creatinine and BUN test deem for collected blood sample to analyse in the doctor’s clinic or lab. 

A phlebotomist will collect the blood sample by tying a stretchable band in the upper arm to make the vein prominent. Then the spot will figured out to draw the blood. After cleaning the area, a hollow needle will be slipped to the vein via your skin to collect the blood. At last, it will be transferred into the test tube and send to lab for detailed analysis.   

Prick or sharp pinch will be felt as the needle makes it way to the vein. Once the process is done, the puncture site will be gauzed and bandaged. A bruise can develop surrounding the puncture site in the next couple of days. But you will never experience long-term or severe pain.

Treatment of initial kidney problem

If initial kidney disease gets detected then the doctor will emphasis to treat its underlying condition. So, you will be prescribed with some medications to keep blood pressure under control (if hypertension is there). Even some suggestions on dietary and lifestyle modifications will be given at the same time.

Endocrinologist reference will be given by your doctor in case you are diabetic. They are specialised in metabolic diseases and ensure the patients by regulating the glucose level in blood.  

For other reasons of unusual kidney function like excessive dose of painkillers and kidney stones, appropriate measures will be taken by the doctor for those disorders management.  

Abnormal test report indicates that you have to retest again within a month. This will help the doctor to keep your condition under observation. See a private doctor today by arranging an appointment and check the working condition of your kidneys.