Clinical Features of Acute Kidney Injury in Patients with Nephrotic Syndrome and Minimal Change Disease: A Retrospective, Cross-Sectional Study
Minimal change disease (MCD) is a common pathological type of nephrotic syndrome, characterized by its sensitivity to glucocorticoids. However, a subset of patients with MCD is at significant risk of developing acute kidney injury (AKI), a complication that can delay remission, necessitate renal replacement therapy, or even lead to chronic renal insufficiency. This study aimed to investigate the clinical characteristics and related factors of AKI in patients with MCD and nephrotic syndrome, providing valuable insights into the mechanisms and risk factors associated with this condition.
The study included 367 patients diagnosed with MCD by renal biopsy from January 1, 2013, to December 31, 2017, at the Chinese People’s Liberation Army General Hospital. These patients exhibited clinical manifestations of nephrotic syndrome, defined by a 24-hour urine protein quantification of more than 3.5 g/d and plasma albumin levels below 30 g/L. Additionally, 586 patients diagnosed with membranous nephropathy (MN) during the same period were included as a control group. The study retrospectively analyzed the clinical and pathological characteristics of these patients, focusing on the incidence and clinical features of AKI across different age groups.
The results revealed that 29.7% of MCD patients developed AKI, significantly higher than the 4.6% observed in MN patients. This finding underscores the heightened susceptibility of MCD patients to AKI compared to those with MN. The study also found that the incidence of AKI increased with age, particularly in patients aged 50 years and older, where the incidence was 52.9%, compared to 22.5% in patients under 50 years old. This age-related increase in AKI incidence suggests that aging, with its associated structural and functional changes in the kidney, may render older patients more vulnerable to acute stressors leading to AKI.
Gender differences were also notable, with a male-to-female ratio of 1.46:1 in MCD patients, and 78% of AKI cases occurring in males. This gender disparity in AKI incidence aligns with previous studies, although the underlying reasons remain unclear. The study also identified several clinical and laboratory parameters that were significantly different between the AKI and non-AKI groups. Patients with AKI were older, had lower serum albumin levels, higher serum creatinine and urea levels, and elevated IgE levels. Additionally, a history of diabetes and hypertension was more prevalent in the AKI group.
The study further explored the renal pathological characteristics associated with AKI in MCD patients. Key pathological features included renal tubular epithelial cell damage, renal tubular atrophy, protein casts, renal interstitial edema, renal interstitial inflammatory cell infiltration, renal interstitial fibrosis, renal intimal thickening, and hyaline degeneration. Multivariate linear regression analysis revealed that renal tubular epithelial cell damage and renal interstitial edema were significantly associated with elevated serum creatinine levels, suggesting that these pathological lesions are primary contributors to AKI in MCD patients.
The findings of this study have several important implications. Firstly, the higher incidence of AKI in MCD patients compared to MN patients highlights the need for heightened vigilance in monitoring and managing MCD patients, particularly those who are older or have comorbid conditions such as diabetes and hypertension. Secondly, the identification of renal tubular epithelial cell damage and renal interstitial edema as key pathological lesions associated with AKI provides potential targets for therapeutic intervention. Understanding the mechanisms underlying these lesions could lead to the development of more effective treatments to prevent or mitigate AKI in MCD patients.
The study also sheds light on the potential role of serum albumin levels in the development of AKI. While lower serum albumin levels were associated with AKI, there was no significant difference in 24-hour urine protein quantification between the AKI and non-AKI groups. This suggests that factors other than proteinuria, such as nutritional intake and liver protein synthesis, may influence serum albumin levels and, consequently, the risk of AKI.
Despite its valuable insights, the study has some limitations. As a retrospective, single-center study, the findings may not be generalizable to all populations. Prospective, multi-center studies are needed to validate these results and further elucidate the mechanisms and risk factors associated with AKI in MCD patients.
In conclusion, this study provides a comprehensive analysis of the clinical and pathological characteristics of AKI in patients with MCD and nephrotic syndrome. The findings highlight the increased risk of AKI in MCD patients, particularly older males, and identify key pathological lesions associated with AKI. These insights have important implications for the monitoring, management, and treatment of MCD patients, with the ultimate goal of reducing the incidence and impact of AKI in this vulnerable population.
doi.org/10.1097/CM9.0000000000001218
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