How to read the results of kidney function test?

Serum urea, nitrogen, and urea are mostly formed by protein breakdown metabolism and are mainly excreted through the kidneys. Kidney diseases such as acute and chronic nephritis, renal arteriosclerosis, renal tuberculosis, renal tumors, severe pyelonephritis, etc. can all cause an increase in serum urea nitrogen. The most commonly used renal function test items

and the analysis of renal function test results are as follows:Serum urea nitrogen urea is almost entirely formed by protein catabolism and is mainly excreted through the kidneys. Kidney diseases such as acute and chronic nephritis, renal arteriosclerosis, renal tuberculosis, renal tumors, severe pyelonephritis, etc. can all cause an increase in serum urea nitrogen. Normal human urea nitrogen is generally below 5.36 micromoles per liter (15 milligrams per deciliter) and not exceeding 7.14 micromoles per liter (20 milligrams per deciliter). If the urea nitrogen exceeds 8.9 micromoles per liter (25 milligrams per deciliter), it is clinically referred to as azotemia, indicating impaired glomerular function; If it exceeds 28.6 micromoles per liter (80 milligrams per deciliter), patients may experience various symptoms of uremia. The concentration of serum urea nitrogen is influenced by food protein, therefore fasting blood must be drawn. Diseases that cause increased protein breakdown metabolism in the body, such as acute infectious diseases, extensive burns, high fever, thyroid dysfunction, etc., can also increase urea nitrogen levels; Patients with upper gastrointestinal bleeding often experience increased protein absorption and elevated urea nitrogen levels. Therefore, it is not accurate to evaluate the degree of renal dysfunction solely based on urea nitrogen, and serum creatinine testing is also necessary. During kidney disease, changes in urea nitrogen occur earlier and more significantly than changes in serum creatinine. Serum creatinine is mainly produced by muscle metabolism, with a very small portion coming from food. The serum creatinine concentration actually depends on the excretion function of the kidneys. The serum creatinine level in healthy males is 70-106 micromoles/liter (0.8-1.2 milligrams/deciliter), and in females it is 53-80 micromoles/liter (0.6.0.9 milligrams/deciliter). According to the concentration of succinic anhydride in blood, renal function impairment can be divided into: (1) mild impairment 132.6-221 micromoles/liter (1.5-2.5 milligrams/deciliter); (2) Moderate damage 229.8-397.8 micromoles/liter (2.6-4.5 milligrams/deciliter); (3) Severe damage greater than 397.8 micromoles per liter. Due to the strong compensatory ability of the kidneys, blood creatinine concentration generally does not increase in the early stages of kidney disease. It only increases when the glomerular filtration capacity decreases by half or more, so its sensitivity is poor. Once creatinine increases, it often indicates a severe prognosis. It should be pointed out that the normal values of serum creatinine and urea nitrogen do not change with age. Due to the increase in body fat, muscle nourishment, and reduced protein breakdown in the elderly, urea nitrogen and creatinine also decrease accordingly. So when the urea nitrogen or creatinine levels of elderly people increase, it indicates that kidney damage has become more obvious and the cause of the disease should be further examined.Details can be found in the Health Self Testing Topic http://exam.fh21.com.cn/jkzc/ .