Shrunken Pore Syndrome: An Overlooked Entity With Major Clinical Consequences

Shrunken Pore Syndrome (SPS) represents an underappreciated form of kidney filtration disorder that is characterized by inadequate filtration of medium-sized molecules in the presence of a relatively preserved glomerular filtration rate (GFR). SPS is usually detected when the GFR measured based on cystatin C levels is significantly below the GFR obtained based on creatinine. SPS has received considerable attention recently due to its association with unfavorable clinical outcomes such as cardiovascular disease, progression of chronic kidney disease, frailty, hospitalization, and death. SPS occurs as a consequence of structural changes in the glomerular filtration barrier that impair the filtration of larger molecules. SPS may be observed in diabetic, hypertensive, inflammatory, or age-related conditions; however, it often goes undetected due to normal results of kidney evaluation based on creatinine. Therefore, early detection of SPS is crucial since it provides a possibility of predicting an unfavorable outcome and identifying patients at risk. The current literature highlights the importance of measuring cystatin C in evaluating kidney function.