Understand your KFT (kidney function test) report better

An overview about the kidneys

We all are aware that the kidneys are the vital organ and it regulates the urinary system. It helps in the filtration of blood and removing all metabolic waste by-products and flushes all toxins out from the body. It also helps in creating a balance of fluids, minerals, acid-base levels, and blood pressure regulation in the body. Several diseases like autoimmune disorders, hypertension, over-consumption of medications as a habit, long persistent infections of the urinary tract, diabetes, any physical injury, and high cholesterol levels might lead to the kidney malfunctioning.

Kidney disease can happen to people of any age and gender. Few factors like sedentary lifestyle, a habit of smoking, alcohol consumption, and over-consumption of habit-forming painkillers are all making the young people more prone to exhibit the kidney diseases. Do not think more just go for the kidney function tests (KFT) and know how your kidneys are doing?

What are the kidney function tests?

There are parameters of different blood and urine tests which can reflect the kidney function. The kidney function tests (KFT) can actually tell how well or bad the kidneys are functioning to eliminate the whole body wastes. Amongst all, urea and creatinine level serves as the main markers to let us know about the kidney function.

What are the different types of a kidney function test?

  1. BUN or Blood urea nitrogen test:

    Proteins break down to form urea in the body. It is filtered by the kidneys from the blood and is removed via urine. This test measures the amount of urea present in blood indicating that kidneys are not functioning properly as they are supposed to filter entire urea from the blood.

    Blood syring - KFT report

  2. Blood creatinine test:

    Creatinine is the metabolic waste by-product formed by our body muscles. It is removed from the blood by the kidneys during the filtration process. If creatinine is found in the blood during the test then it signifies a malfunctioning of the kidneys indicating some kidney problem.

  3. Urinalysis:

    In this test presence of protein and blood cells like red blood cells and white blood cells reveals improper filtration done by the kidneys. Their corresponding values can indicate kidney disease which can be analyzed by your doctor.

  4. Creatinine clearance test:

    This test helps in knowing the filtration rate of creatinine by the kidneys. In this comparison of creatinine levels in the blood as well as urine is made.

  5. Urea clearance test:

    In this test blood plasma volume measurement is done per minute after the kidneys remove urea from it. This test involves comparison of urea present in blood and the urine. High value of the test exists in persons with malfunction kidneys.

  6. Glomerular filtration rate (GFR) or estimated filtration rate (eGFR):

    This test identifies the fluid filtration rate of the kidneys. Its evaluation is made by measuring the clearance value of the kidneys. The formula-based value of eGFR is calculated based upon blood creatinine level, gender, and age however it is an approximate value.

When to see a doctor?

As we age our body organs age with us. The filtration capacity of the kidneys naturally tends to decline gradually beyond the age of 30. Any kidney disease might not come to notice until it becomes prominent and majorly affects the system. To avoid any long term complications and even ending up of small kidney malfunctions into a big one. You must get regular assessments of kidney function, especially after the 50s.

What do the results tell us?

Different values of the tests help in assessing the functioning of the kidneys. Although different reference ranges are preferable by different labs. Few of the preferable lab ranges for reference are as follows:

  1. BUN:

    Normal range appears between 7 to 20 mg/dL, the value between 20 to 40 mg/dL is an indication of higher value revealing and impaired kidney function. These elevated levels of BUN usually appear in cases of high-protein diets, excessive medication intake, and dehydration.

  2. Blood creatinine levels:

    Normal range for males is 0.8 to 1.2 mg/dL and for females is 0.6 to 0.9 mg/dL. Any level beyond these indicates improper functioning of the kidney. Further with disease progression creatinine levels in blood increases.

  3. Urinalysis:

    Usually minimal quantity of protein present in the urine is normal. However, its normal range is between 0 to 20 mg/dL. Any value of protein greater than the normal along with blood cells in urine indicates early symptoms of few kidneys diseases like kidney stones, urinary bladder infections, chronic kidney disease, and diabetic neuropathy. High levels of protein in urine can sometimes after heavy physical exercise as well.

  4. Creatinine clearance:

    Its normal range from 85 to 125 ml/min for male and 75 to 115 ml/min for female. Level lesser than the normal range reveals kidney malfunction. Low creatinine clearance indicates the reduction inability of the kidneys to filter waste from the blood with high levels of creatinine and urea floating in the blood.

  5. Urea clearance:

    Normal range for this is 65 to 99 ml/min. As per that, the kidney removes whole urea in 65 to 99 ml of blood plasma per minute.

    kidney function

  6. Glomerular filtration rate:

    Normal range is 90 to 120 mL/min/1.73 m2; 60 to 89 mL/min/1.73 m2 for mild chronic kidney disease (CKD); 30 to 59 mL/min/1.73 m2 for moderate CKD; 15 to 29 ml/min/1.73 m2 for severe CKD and <15 mL/min/1.73 m2 indicates kidney failure with an urgent need of dialysis. This value is even affected by aging even in absence of any kidney disorders.


KFT must be done during regular health checkups at least yearly. Diseases like diabetes and hypertension leaves a damaging impact on the kidneys and alters its functioning. Hence screening at regular interval becomes essential.

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