What are the items included in kidney function tests?

Feb 25, 2023 Source: Cainiu Health

Dr. Yang Ziqi

Introduction

Kidney function tests include serum blood urea nitrogen, serum creatinine, uric acid, cystatin C, and renal color Doppler ultrasound. In addition to these tests, kidney CT scans can also be used to evaluate kidney function. To avoid affecting test results, it is essential to fast during the examination, and for three days prior to testing, avoid consuming overly greasy or spicy foods.

Kidney function tests include serum urea nitrogen, serum creatinine, uric acid, cystatin C, and renal color Doppler ultrasound. The details are as follows:

1. Serum Urea Nitrogen

Serum urea nitrogen is a nitrogen-containing compound in plasma other than protein and is also an end product of protein metabolism. It is typically metabolized in the liver and eventually converted into urea. Urea is filtered through the glomeruli and excreted in urine. Therefore, elevated serum urea nitrogen levels indicate impaired kidney function. Testing serum urea nitrogen helps screen for and diagnose various kidney diseases.

2. Serum Creatinine

Serum creatinine is one of the laboratory tests used to evaluate kidney function. Creatinine is the final metabolic product of muscle metabolism. When muscle cells age or die normally, creatine is produced, which then undergoes dehydration to gradually form creatinine, ultimately being released into the bloodstream. Creatinine is hardly reabsorbed by renal tubules and is normally excreted completely in urine. Thus, when kidney function is impaired and excretion is hindered, serum creatinine levels rise.

3. Uric Acid

Uric acid is the end product of purine metabolism and plays a role in scavenging oxygen free radicals and antioxidant activity. It is one of the non-protein nitrogenous metabolic products in the human body. Measuring blood uric acid levels can help determine whether there is a disorder in purine metabolism. Elevated uric acid levels may occur in patients with gout, chronic nephritis, leukemia, or after intense physical exercise, and timely medical evaluation and treatment are recommended.

4. Cystatin C

Cystatin C is an inhibitor of cysteine proteases and serves as an endogenous marker of glomerular filtration rate (GFR). Elevated levels reflect, to some extent, a decline in glomerular filtration function and indicate kidney damage.

5. Renal Color Doppler Ultrasound

Renal color Doppler ultrasound allows assessment of changes in kidney morphology, structure, and size, as well as evaluation of renal blood flow, thereby helping to determine whether kidney function is abnormal.

In addition to the above tests, renal CT scans can also be used to assess kidney function. To avoid interference with test results, patients should remain fasting during testing and avoid consuming overly greasy or irritating foods for at least three days prior to the examination.

View All

How long does it take to get the results for liver and kidney function blood tests drawn at 10 a.m.?

Liver function and kidney function refer to tests that assess the health of the liver and kidneys. Blood is typically drawn at 10 a.m. for these tests, and results are generally available around 2 p.m. Liver and kidney function tests are common clinical examinations used to evaluate the condition of the liver and kidneys, usually performed by analyzing peripheral blood samples. These tests are typically conducted using specialized biochemical instruments and results can be obtained within approximately four hours.