[Clinical features and the process of renal stone formation in elderly patients with calculous pyelonephritis]

Aim: Calculous pyelonephritis is a severe infectious disease that predominantly affects the elderly population. However, there are few detailed reports on the stone formation process in calculous pyelonephritis. The purpose of this study was to investigate the process of calculous pyelonephritis formation and to identify markers of its onset.

Methods: In this study, we examined the process of stone formation through follow-up observation of 13 episodes of 10 cases of calculous pyelonephritis that were experienced in a nursing home, in which abdominal CT was performed multiple times. Additionally, we analyzed the usefulness of eGFR values before and after the onset of calculous pyelonephritis. We also investigated the treatment options for calculous pyelonephritis.

Results: The cases were characterized as elderly (range: 76-100 years, median: 89.5 years), and all patients had underlying diseases. Four patients had a performance status (PS) of 4, and the remaining patients had a PS of 3. In 11 of the 13 episodes, diagnostic imaging was performed multiple times, making it possible to analyze the process of stone formation over time, and cases in which stones increased in a short period of time were observed. When the change in eGFR before and after the onset of calculous pyelonephritis was evaluated using the Wilcoxon signed-rank test, a significant decrease was observed before and after the onset of calculous pyelonephritis (p<0.02). As a result of the bacterial culture, multiple bacteria were detected in the urine culture in 4 episodes, and ESBL-producing bacteria were detected in 4 episodes. When calculous pyelonephritis was diagnosed, all episodes involved hospitalization at a general hospital and intravenous antibiotic treatment was administered. Regarding the prognosis of calculous pyelonephritis, 4 of the 10 cases examined died.

Conclusions: We analyzed the clinical features and process of kidney stone formation in elderly patients with calculous pyelonephritis and showed that stones grow in a short period of time in some elderly patients. We also found that the eGFR after the onset of calculous pyelonephritis was significantly lower than that before the onset of the disease.