Kidney function examination is an examination procedure carried out to find out how well the kidneys are working and to detect interference with the organ. On examination of kidney function, blood and urine of the patient will be taken for later observed in the laboratory.
Kidney is a pair of organs located behind the abdominal cavity (retroperitoneal), and serves to remove residual substances and excess fluid from the blood. In addition to maintaining fluid balance, this organ also serves to maintain the balance of mineral levels in the body, and helps the formation of vitamin D, red blood cells, and hormones that regulate blood pressure.
If a person experiences kidney damage, the kidneys cannot perform their functions optimally causing various disorders in the body. To detect the presence of kidney disease and determine whether the kidneys are working properly, a person must undergo an examination of kidney function.
Types of Kidney Function Examination
There are kidney function checks that are routinely done and some are additional in nature. The types of kidney function checks that are routinely done are:
- Urine test, to determine the presence of protein and blood in urine that indicates a decrease in kidney function.
- Ureum or blood urea nitrogen (BUN), which is a test to determine the level of urea nitrogen in the blood which is a waste of protein metabolism and should be discharged through the kidneys.
- Blood creatinine, which is a test to determine blood creatinine levels. Creatinine is a residual substance from the breakdown of muscles that will be removed through the kidneys. High creatinine levels in the blood can be a sign of interference with the kidneys.
- Glomerulo filtration rate (GFR), which is a test to see the ability of the kidneys to filter metabolic waste from the body.
Whereas additional kidney function checks include:
- Test the content of albumin in the blood.
- Albumin-creatinine ratio test.
- Tests for electrolyte content in blood and urine.
- Creatinine clearance (CCT) and protein in urine 24 hours.
- Kidney biopsy.
- Cystoscopy and ureteroscopy.
Indications for Kidney Function Examination
Examination of kidney function is generally recommended in patients suspected of suffering from acute kidney failure and chronic kidney failure. Symptoms that can indicate kidney damage are:
- Pain when urinating.
- Having difficulty at the beginning of urination.
- Hematuria.
- Increased frequency of urination or reduced urine production.
- Foamy urine.
- Swelling of the hands and feet due to a buildup of fluid (edema).
- High blood pressure.
- Arrhythmia.
- Hard to breathe.
- Loss of consciousness.
A person can also be asked to undergo kidney function tests if he has conditions such as:
- Diabetes.
- Heart disease.
- Hypertension.
- Kidney stones.
- Lupus
- Infection.
- There are family members with a history of kidney disease.
Kidney Function Warning Checks
There is no special warning for patients who will undergo kidney function tests, both blood and urine samples. However, patients who are taking blood-thinning medications or have blood clotting abnormalities should inform their doctor about the condition.
Preparation for Kidney Function Examination
Patients will be asked to stop taking certain drugs so that the results of kidney function tests are not affected. Specifically for patients who will undergo urine testing for 24 hours, they will be asked to avoid strenuous physical activity on the day of urine collection. This is because heavy physical activity can affect the concentration of creatinine found in urine.
Patients who will undergo an examination of kidney function will also be asked to fill in their personal data and medical history for the completion of the examination. In addition to blood creatinine levels, personal data such as age, race, sex, height, and weight are important for calculating glomerular filtration rate (GFR).
Procedure for Sampling Kidney Function Examination
Examination of kidney function is done through blood and urine samples. Blood samples are taken using special needles for analysis in the laboratory. First, the doctor will tie the patient's upper arm with a special strap, so that the veins are clearly visible. After that, the doctor will clean the skin in the venous area using alcohol. The doctor will then insert a special needle into the vein, and place a blood sample tube on the needle. Blood will flow from the veins into the tube. If it is deemed sufficient, the needle will be removed and the point of the needle prick on the skin will be covered with special plaster.
As for urine samples, taken when the patient urinates and is stored in a special container. At the time of urination, let the amount of urine at the beginning of urination is wasted without being accommodated. After that, collect enough urine into the sample container and cover tightly. If it is finished, the urine can be directly taken to the laboratory for inspection or stored in the refrigerator first.
Patients can be asked to collect urine samples for 24 hours. If asked to take a urine sample for 24 hours, the patient must collect urine every time he urinates into the sample container. During the sampling process, storage containers must also be stored in the refrigerator before being taken to the laboratory for inspection.
After Examination of Kidney Function
Samples that have been taken from patients will then be taken to the laboratory for examination. In the next meeting schedule, when the results of the laboratory examination are available, the doctor will read the results of the examination.
In a urine test, the results can indicate abnormalities or kidney disease from abnormal substances in the urine, such as sugar (glucose), protein, and red blood cells. In a healthy kidney, the amount of these substances is very little or even none at all. However, the presence of these substances does not always indicate that a person has kidney disease. Urine test results are only a sign of an unusual or abnormal condition in a person's kidney.
In patients with kidney disorders, the concentration of urea in the blood also increases. However, high concentrations of urea in the blood can also be found in someone who is dehydrated, taking certain medications, or regularly consuming high protein foods. Therefore, before undergoing an ureum examination, patients must provide information about health conditions and the activities they undergo in full.
Albumin test results show the content of albumin in the blood. Albumin is a protein that should be reabsorbed by the kidneys, not entirely discharged through urine. When the kidney's re-absorption function decreases, the albumin content in the blood will also decrease. Conversely, creatinine is a substance that should be discharged through urine, so that if there is a decrease in kidney function, creatinine levels in the blood will increase. The content of albumin and creatinine can be known quantitatively, and the ratio can be calculated to determine the condition of the kidneys. A high ratio indicates the beginning of leaking of albumin through urine.
From the various results of tests carried out as well as considering the medical history factor and patient's personal data, the condition of the kidney can be concluded through the GFR (glomerulo filtration rate) indicator. GFR in normal kidneys is generally above the value of 60. GFR which is between values 15-60 indicates the presence of kidney disease or kidney failure. Whereas GFR below 15 indicates final stage renal failure requiring renal replacement therapy.
After the results of the kidney function examination are known, the doctor will make a diagnosis of the disease being experienced by the patient. If needed, the kidney doctor can ask the patient to undergo additional tests to make the diagnosis more accurate. Patients suspected of suffering from hypertension based on test results, will be given medication according to the conditions suffered. Hypertensive patients can also be recommended to change their lifestyle and diet. If you are suspected of having diabetes, the patient can be referred to an endocrinologist for further treatment.
Risk of Kidney Function Examination
Taking urine samples on examination of kidney function is generally safe and does not cause side effects. While in blood sampling, the risk of side effects is present, but rarely occurs. Among others are:
- Bleeding.
- Infection at the sampling site.
- Rash.
- Pain.
