Selectin Index (SPI)

The Selective Protein Index (SPI) is an auxiliary test used to check if the kidneys are normal. Because the degree of damage to glomerular capillaries is different, the proportion of various proteins in different molecular weights in urine is different. Based on this, the concept of urinary protein selectivity, that is, the passage of glomerular capillary wall to plasma protein is proposed. There is selectivity. The renal clearance rate of plasma proteins with large differences in molecular weight is often determined clinically, and the ratio is calculated as the selectivity index (SPI). The blood and urine concentrations are usually determined by immunoturbidimetric assay or one-way immunodiffusion method using transferrin (molecular weight 79,000) and IgG (molecular weight 170,000), respectively. Basic Information Specialist classification: urinary examination classification: urine / kidney function test Applicable gender: whether men and women apply fasting: not fasting Tips: Maintain regular routines and diet to help the inspection go smoothly. Normal value SPI's judgment criteria: 1. SPI ≤ 0.1 is the height selection. When the glomerular filter is normal, only the protein with a molecular weight of <40,000 is allowed to pass, and the larger component can only filter a small amount, so it has a high selectivity. 2. SPI ≥ 0.2 is a low choice. 3. SPl0.1 ~ 0.2 is a moderate choice. Clinical significance Abnormal results: 1. Minimal lesion type urine protein is highly selective, hormone and cytotoxic drugs are effective, and about 95% of patients have normal renal function. 2, focal sclerosis type is often low selective urine protein, hormone and cytotoxic drugs are often ineffective, 50% of patients can develop renal insufficiency, need dialysis and kidney transplantation treatment. 3, membranous nephropathy, its SPI often changes, some patients are sensitive to hormones and cytotoxic drugs, 30% to 50% of patients need to receive dialysis or kidney transplantation. In addition, although the SPI of different pathological types of nephrotic syndrome is different, there are also overlapping phenomena. Therefore, in the clinical judgment, it is necessary to combine other laboratory tests for comprehensive analysis. People who need to be examined: suspected to be a kidney disease patient. Precautions Taboo before the examination: Maintain regular routines and diet to help the inspection proceed smoothly. Requirements for examination: The patient takes the urine according to the doctor's examination, the doctor carefully checks and carefully observes the result. Inspection process By measuring the size and composition of the protein molecules in the urine, the extent of filtration membrane damage can be shown. The degree of urinary protein selectivity can be determined by the urinary protein selectivity index: urinary protein selectivity index (urine IgG ÷ blood IgG) ÷ (urine transferrin ÷ blood transferrin). The selectivity index O.2 indicates that a large amount of large molecular weight protein is excreted in the urine, suggesting that the glomerular filter damage is less effective than the heavy hormone treatment. The selectivity index is between 0.1 and 0.2, and the hormone effect is not very satisfactory. For patients with mild proteinuria, this test has little reference value and should be used for disk electrophoresis of urine protein. Not suitable for the crowd Inappropriate people: Generally, there is no suitable for the crowd. Adverse reactions and risks No related complications or hazards.