Physical examination of renal function examination items

The physical examination of renal function usually includes indicators such as blood urea nitrogen, blood creatinine, serum cystatin C, urinary microalbumin, and estimated glomerular filtration rate. These examinations are helpful to evaluate the renal excretion function, glomerular filtration capacity and early renal damage, and are mainly used to screen chronic kidney disease, diabetes nephropathy, hypertensive kidney damage and other diseases.

1. Blood urea nitrogen

Blood urea nitrogen is the end product of protein metabolism, which is excreted from the body through glomerular filtration. The normal range is generally between 2.9-8.2 millimoles per liter, and an increase in the value may indicate decreased kidney function, high protein diet, or gastrointestinal bleeding. During testing, it is necessary to collect 2-3 milliliters of venous blood on an empty stomach. Intense exercise or menstrual periods may affect the accuracy of the results.

2. Blood creatinine

Blood creatinine is an endogenous substance produced by muscle metabolism, which is not reabsorbed after glomerular filtration. The normal reference range for males is 54-106 micromoles per liter, and for females it is 44-97 micromoles per liter. This indicator is not affected by diet but may change due to changes in muscle content. Elderly people or those with muscle atrophy may have lower values, and it needs to be judged comprehensively in conjunction with other indicators.

3. Serum cystatin C

Serum cystatin C is a low molecular weight protein constantly produced by nucleated cells, which can more sensitively reflect changes in glomerular filtration function. The normal value is usually lower than 1.16 mg/L. This test is not affected by age, gender, muscle volume and other factors. The detection rate of early renal function damage is better than that of serum creatinine, and is especially suitable for renal function monitoring in diabetes patients.

4. Urine microalbumin

Urine microalbumin detection can find 20-200 micrograms of low concentration albuminuria per minute, which is the earliest clinical manifestation indicator of diabetes nephropathy. A mid morning urine or 24-hour urine sample should be collected, and vigorous exercise and menstrual period interference should be avoided before examination. A positive result may indicate early damage to the glomerular basement membrane charge barrier.

5. Estimation of glomerular filtration rate

is calculated by combining blood creatinine values with parameters such as age, gender, weight, etc. The normal value is greater than 90 milliliters per minute. This indicator can more accurately reflect the actual filtration function of the kidneys, and the staging of chronic kidney disease is mainly based on this value. The estimation formula includes MDRD and CKD-EPI, with the latter being more sensitive to mild renal dysfunction.

Before conducting a kidney function test, it is necessary to maintain a normal diet for 3 days to avoid high protein intake, and fasting in the morning of the test day. It is suggested that patients with hypertension and diabetes should recheck their renal function indicators every six months, and the general population should include basic renal function examination in their annual physical examination. Pay attention to perineal hygiene before urine test, and women should avoid menstrual periods. If abnormal indicators are found, timely treatment should be sought in the nephrology department, and further examinations such as renal ultrasound or renal biopsy should be conducted if necessary.