Examining 1,195 patients post-radical nephrectomy, this study suggests that kidney cysts, especially in the medulla, may serve as valuable imaging biomarkers for progressive chronic kidney disease.

The following is a summary of “Association of Kidney Cysts With Progressive CKD After Radical Nephrectomy,” published in the January 2024 issue of Nephrology by Sabov et al.

In this study, the researchers aimed to explore the relationship between simple kidney cysts, a commonly observed condition often deemed clinically inconsequential, and their association with progressive chronic kidney disease (CKD). Conducted as an observational cohort study, the research focused on patients who underwent radical nephrectomy for a tumor, utilizing pre-surgical CT or MRI imaging to evaluate parenchymal cysts with a diameter of at least 5 mm. 

The exposure of parenchymal cysts in the retained kidney was analyzed in correlation with microstructural findings from kidney histology. The primary outcomes were defined as progressive CKD, encompassing events such as dialysis, kidney transplantation, a sustained >40% decline in eGFR, or an eGFR <10 ml/min/1.73m² that remained at least 5 ml/min/1.73m² below the post-nephrectomy baseline for a minimum of 3 months. Employing Cox models, the study group assessed the risk of progressive CKD, adjusting for various baseline factors. Results from a cohort of 1,195 patients over a median of 4.4 years of follow-up revealed that a higher number of cysts, particularly in the medulla, exhibited a stronger association with progressive CKD. Baseline imaging indicated that 37% of patients had at least one cyst, 34% had at least one cortical cyst, and 8.3% had at least one medullary cyst. 

The study identified modest correlations between the number of cysts and larger nephrons and more nephrosclerosis in kidney histology. While acknowledging certain limitations, such as the potential differences in patients undergoing radical nephrectomy compared to the general population and the lack of genetic testing, their findings suggest that kidney cysts, especially in the medulla, warrant further investigation as potentially valuable imaging biomarkers for progressive CKD, extending beyond the current clinical assessment of kidney function and conventional CKD risk factors.

 Source: sciencedirect.com/science/article/pii/S0272638624000465