Why do I need to test for kidney disease with a kidney test kit?
The kidneys are one of the most important organs of the human body, whose functions are mainly to secrete and excrete urine, waste products, poisons and drugs; to regulate and maintain the volume and composition of body fluids (water and osmolality, electrolytes, acidity and alkalinity); and to maintain the balance of the body's internal environment (blood pressure, endocrine). Approximately 180 L of plasma is filtered through the glomerulus daily.
Allergic reactions, infections, renal vasculopathy, metabolic abnormalities, congenital diseases, systemic circulatory and metabolic diseases, drugs, and toxin damage to the kidneys can affect renal function, which is mainly manifested by abnormalities in the indicators of renal function tests, so it is important to use the kidney test kit to diagnose renal diseases.
The indicators used in the kidney test kit to check kidney function are serum urea, blood creatinine, uric acid, etc.
(i) Serum urea (BUN)
Serum urea is the metabolite of human protein, which is mainly excreted with urine through glomerular filtration. When the kidney parenchyma is damaged, the glomerular filtration rate decreases, resulting in an increase of serum urea concentration in the blood, so the glomerular filtration function can be understood by measuring urea.
1. Kidney test kit test results increase
(1) When kidney diseases such as acute renal failure, chronic nephritis, renal arteriosclerosis, chronic pyelonephritis, renal tuberculosis, advanced renal tumor, etc., the BUN can be unchanged when the kidney function is mildly impaired. BUN increases only when 60% to 70% of effective kidney units are damaged. Therefore, BUN measurement cannot be used as an indicator of early renal impairment, but it has special value for the diagnosis of renal failure, especially uremia, and can judge the condition and estimate the prognosis. A. In compensated renal failure, Ccr decreases, blood Cr is normal, BUN is normal or mildly elevated (<9 mol/L), B. In decompensated renal failure (azotemia or pre-uremia), Ccr decreases significantly (<0.83 ml/s), blood Cr increases (>90 mmol/L) and BUN is moderately elevated (>9 mmol/L). (>9mmol/L). C. Uremic stage Ccr<0.33ml/s, blood Cr>445μmol/L, BUN>20mmol/L.
(2) Pre-renal or post-renal factors causing significant reduction in urine output or urinary closure, such as dehydration, edema, ascites, circulatory failure caused by violent vomiting and diarrhea, and urinary obstruction caused by urinary stones, prostate hypertrophy, tumors, etc.
(3) Excessive protein decomposition in the body, such as large burns, after major surgery, upper gastrointestinal bleeding, hyperthyroidism and acute infectious diseases. At this time, BUN is increased, while other renal function test results are more or less normal.
2. Decreased kidney test kit results: It is less common clinically. It is mainly due to the damage of liver parenchyma and reduced production. Such as acute yellow liver atrophy, liver cirrhosis, toxic hepatitis, severe anemia, etc.
Possible diseases with high results: Uremia, renal failure
(ii) Blood creatinine
Serum creatinine concentration can accurately reflect the degree of damage to glomerular filtration function to a certain extent. When the renal function is normal, the creatinine excretion rate is constant. When the renal parenchyma is damaged, the glomerular filtration rate will be reduced. When the filtration rate decreases to a certain degree, the blood creatinine concentration will rise sharply.
1. Kidney test kit test results increase
Changes in serum creatinine concentration are determined primarily by the filtration capacity of the glomerulus (glomerular filtration rate). When the filtration capacity decreases, the creatinine concentration increases. Higher-than-normal blood creatinine values most often mean kidney damage. Although creatinine is a more accurate indicator of kidney parenchymal damage, it is not a sensitive indicator. It is only when the glomerular filtration rate decreases to a certain level that the blood creatinine rises significantly.
In other words, because of the strong metabolic ability of human kidneys, when kidney damage is mild, the general discomfort is not obvious, so when many people really experience nausea, vomiting, dizziness and other symptoms, the kidneys have actually been seriously damaged, and blood creatinine starts to rise significantly at this time.
Serum creatinine can behave normally until the glomerular filtration rate drops to 50%. In other words, when more than half of the functional kidney units are lost, serum creatinine rises, and at this point, chronic renal failure is compensated, and the general rule is that the serum creatinine value at this stage is 176.8 μmol/L (2 mg/dl). When the glomerular filtration rate drops below 25%, the serum creatinine rises sharply, up to 5 mg/dl or more, which is generally the uremic phase. In complete loss of renal function (e.g., acute renal failure), serum creatinine increases by 88.4 to 265.2 μmol/L per day; if it is less than this range, it indicates that residual functional renal units remain, and conversely, it indicates skeletal muscle lysis.
High blood creatinine and rising blood creatinine can be a sign of renal impairment, i.e., a kidney problem, but high blood creatinine alone can also be a sign of hyperthyroidism, acromegaly, etc. Therefore, when the blood creatinine rises, it is important to correlate other tests about the kidney to avoid misdiagnosis or delay. Decreased blood creatinine is generally common in pregnancy, muscular atrophic lesions and liver dysfunction.
When the blood creatinine exceeds the normal value during physical examination or unintentionally, it is better to pay attention to this problem and consult the doctor so that he or she can make an accurate analysis and diagnosis by combining the medical history and other laboratory tests to clarify the cause of the disease and treat it early.
2. Decreased kidney test kit results
It is seen in progressive muscular atrophy, leukemia, anemia, liver dysfunction and pregnancy.
(iii) Uric acid
Uric acid is the end product of purine metabolism in the body. It is mainly excreted by the kidneys, so the measurement of uric acid can understand the function of the kidneys. Increased is seen in-
1. Gout
An increase in serum uric acid is the main basis for the diagnosis of gout.
2. Renal lesions
Acute or chronic nephritis, pyelonephritis, renal tuberculosis, etc. can increase serum uric acid.
3. Malignant tumor
Various malignant tumors can lead to elevated serum uric acid.
Normal value reference range
1. Serum urea
- Adult: 3.2～7.1μmol/L
- Infants, children: 1.8～6.5 mmol/L
Blood urea nitrogen: elevation may be related to excessive protein intake
Blood urea nitrogen (BUN) is the end product of protein metabolism, and urea is mainly excreted in the urine by glomerular filtration. Like the blood creatinine concentration, once the urea nitrogen concentration changes, it means that the kidney function has been impaired.
However, an elevation of this indicator alone does not necessarily mean that the kidney is hypoplastic and requires a physician to analyze it in conjunction with the presence of the following symptoms:
- Acute infectious diseases.
- High fever.
- Hemorrhage in the upper gastrointestinal tract.
- Massive burns, severe trauma.
- Major surgery and hyperthyroidism.
- High protein diet.
2. Blood creatinine
- Males: 62～115μmol/L
- Female: 53～97μmol/L
Attention!
When you see that the blood creatinine in the Kidney Test Kit test result is within the normal range, many people will think that there is nothing wrong with the kidney. In fact, if the blood creatinine is close to the maximum of the normal value, it should be taken seriously. Especially if urine protein or hematuria appears in urine routine, you need to see a doctor for examination.
Changes in blood creatinine concentration are commonly seen in the following conditions.
- Decreased glomerular filtration function, resulting in increased blood creatinine concentrations.
- A person with strong muscles may have a high blood creatinine concentration and there is no cause for concern.
- The blood creatinine concentration is generally low in the elderly, the wasted or malnourished, and once it is high, it is time to be alert.
3. Uric acid
- Males: 150～440μmol/L
- Female: 95～360μmol/L
Uric acid (UA) is a metabolite of purines in the body's nucleic acids. Most of the uric acid in the blood is filtered by the glomerulus, except for a small portion that is destroyed by the liver.
An increase in blood uric acid can have the following main causes.
- High purine diet.
- Impairment of glomerular filtration function.
- Primary gout due to hereditary enzyme defects, and secondary gout due to massive cell destruction from a variety of blood disorders and malignancies.
The third type of patient above does not necessarily have a problem with kidney function, but persistent elevated uric acid can lead to kidney damage.
References
See also:
1. 9 Best At-Home Kidney Tests Buyers Guide In 2022
2. Chronic Kidney Disease: Causes, Symptoms And Management
3. How important is a tester with kidney test function?
4. What is anemia with kidney disease?