Kidney Function Tests: Purpose And Types

The kidneys perform a range of functions that contribute to maintaining a healthy balance of chemicals in the blood. Among the most significant is filtering the waste from the bloodstream and flushing the excess fluid and waste material from the body in the form of urine. Apart from waste management, the kidneys also control the essential minerals and water levels within the body. In addition, the kidneys are also responsible for producing red blood cells, vitamin D and hormones that regulate the blood pressure. 

 

When the kidneys start losing their filtering capability, it leads to the build up to excess toxins and impurities in the body, causing a possible damage to the kidneys, which can be life threatening if left untreated.

 

Why are these tests prescribed?

 

In cases where the doctors doubt the optimal function of the kidneys, you may need to take up kidney function tests (KFTs). KFTs are also known as Kidney Function Panel, Kidney Panel, and Renal Function Panel. These simple blood tests help identify issues related to the kidneys. These tests are prescribed as part of routine health examinations to detect any kidney-related diseases and to pinpoint individuals who may be vulnerable to renal ailments. Notably, this test may also be prescribed to people having diabetes as they have a higher risk of developing CKD (Chronic Kidney Disease) - a condition where the kidneys undergo gradual damage, resulting in compromised blood filtration.

 

What are the symptoms of CKD?

 

Here are some signs of kidney disease:

 

With the rapid progression of kidney disease, the signs and symptoms of CKD emerge gradually. Reduced kidney function can lead to the accumulation of fluid, waste products, and electrolyte imbalances within the body. The extent of kidney function loss determines the range of symptoms experienced:

 

• Dry and itchy skin
• Frequent urination
• Feeling tired or trouble concentrating
• Trouble sleeping
• Blood in your urine
• Foamy urine
• Persistent puffiness around your eyes
• Swollen ankles and feet
• Poor appetite
• Muscle cramps

 

The signs and symptoms of kidney disease are often vague and not distinctive. 

 

What are the different types of KFTs?

 

The KFTs are prescribed to get the best overview of how the kidneys are functioning. The main components of a KFT include:

 

Blood Urea Nitrogen (BUN): The test measures the amount of urea nitrogen present in the blood. It is a waste product formed by the liver during the break down of proteins. After it is formed in the liver, it is filtered out of the blood by the kidneys and leaves the body through urine. The BUN levels are elevated if the kidneys are not able to remove urea from the blood normally. 

 

Serum Creatinine: Creatinine is a byproduct formed during muscle metabolism. As a waste product, the kidneys filter out creatinine from the blood and remove it in the form of urine. Higher levels of serum creatinine may suggest a problem with the kidneys.

 

Glomerular Filtration Rate (GFR): Glomeruli are tiny filters in the kidneys that help in removing toxins from the blood. The estimated glomerular filtration rate (eGFR) calculates the amount of blood these filters clean every minute based on your body size. eGFR helps detect the disease early so as to stop the damage to the kidneys.

 

Creatinine Clearance (CrCl): It is the measurement of how effectively the kidneys are clearing creatinine from the blood. Abnormal levels of creatinine present in both the urine and blood may indicate an issue like kidney disease.

 

Serum Electrolytes: It evaluates the body’s main electrolytes - sodium, potassium and calcium. Any imbalance in the levels of these electrolytes can indicate kidney dysfunction.

 

Urine Analysis: It is a test that takes a close look at different urine components in a sample. It includes assessing the presence of protein, blood, glucose, and other substances.

 

In conclusion, KFTs play a crucial role when there are concerns about kidney performance. Often included in routine health assessments, they aid in diagnosing kidney diseases and finding individuals at risk, especially those with diabetes who are more susceptible to CKD.

 

Sources:
https://www.healthline.com/health/kidney-function-tests
https://www.cdc.gov/kidneydisease/publications-resources/kidney-tests.html