Selectin index

Selective protein index (SPI) is an auxiliary test method used to check whether the kidneys are normal. Due to the different degree of damage to glomerular capillaries, the ratio of various proteins of different relative molecular weights in urine is different. Based on this, the concept of urinary protein selectivity is proposed, that is, the passage of glomerular capillary walls to plasma proteins. There is selectivity. Clinically, the renal clearance of two plasma proteins with large differences in molecular weight is often measured, and the ratio is calculated to give the selectivity index (SPI). Generally, transferrin (molecular weight 79,000) and IgG (molecular weight 170,000) are used to measure blood and urine concentrations by immunoturbidimetric method or one-way immunodiffusion method, respectively.