NEW research has noted an association between kidney cysts with progressive chronic kidney disease (CKD) risk, following radical nephrectomy.
Partial nephrectomy is the removal of part of the kidney, and radical nephrectomy denotes the removal of the entire kidney. The procedure is commonly performed to remove a tumour, isolate a healthy kidney for organ transplantation, or treat a diseased kidney.
A previous study, made up of 65 patients who underwent a radical nephrectomy, identified a higher risk of progressive CKD in the 20 patients with a renal cyst compared to the 45 patients who did not have them. Andrew D. Rule, Mayo Clinic, Rochester, Minnesota, USA, and team expanded on this study with a larger cohort of 1,195 patients.
They examined whether the kidney cyst size, number, and location were associated with concurrent clinical characteristics, measures of nephron size or nephrosclerosis on kidney histology, and progressive CKD during follow-up observation. Fifty of the patients had experienced progressive CKD over a median of 4.4 years of follow-up. Progression was defined as dialysis, kidney transplantation, a sustained estimated glomerular filtration rate (eGFR) less than 10 mL/min/1.73m2, or a more than 40% decline in eGFR that was at least 5 mL/min/1.73m2 below the post-nephrectomy baseline.
From the cohort, 38% subjects had at least one cyst, 34% had at least one cortical cyst, and 8.7% had at least one medullary cyst. Interestingly, there was a proportional relationship between the number of cysts and the risk of progressive CKD. Additionally, cysts found in the deeper tissue of the kidney, the medulla, yielded a greater progressive CKD risk than those found in the outer cortex.
Whilst the observed association between progressive CKD risk and kidney cysts is an important finding, Rule noted several limitations of the study. Firstly, he highlighted that the cohort only involved those that had undergone radical, not partial, nephrectomy. He theorised that radical nephrectomy may accelerate the risk of progressive CKD, due to hyperfiltration in the remaining kidney. Secondly, lesions located in the intersection between the cortex and medulla, known as the corticomedullary junction, were characterised as cortical lesions; however, these could arguably be defined as medullary. Finally, the cohort was predominantly White, with results possibly varying between ethnic groups.
