Time-averaged proteinuria during follow-up and renal prognosis in patients with biopsy-proven benign nephrosclerosis

Morphometric analysis of chronicity on kidney biopsy: a useful prognostic exercise

Chronic changes on kidney biopsy specimens include increasing amounts of arteriosclerosis, glomerulosclerosis, interstitial fibrosis and tubular atrophy, enlarged nephron size, and reduced nephron number. These chronic changes are difficult to accurately assess by visual inspection but are reasonably quantified using morphometry. This review describes the various patient populations that have undergone morphometric analysis of kidney biopsies. The common approaches to morphometric analysis are described. The chronic kidney disease outcomes associated with various chronic changes by morphometry are also summarized. Morphometry enriches the characterization of chronicity on a kidney biopsy and this can supplement the pathologist's diagnosis. Artificial intelligence image processing tools are needed to automate the annotations needed for practical morphometric analysis of kidney biopsy specimens in routine clinical care.

The diagnostic value of native kidney biopsy in low grade, subnephrotic, and nephrotic range proteinuria: A retrospective cohort study

Background

In nephrotic range proteinuria of adult-onset, kidney biopsy is the diagnostic gold standard in determining the underlying cause of disease. However, in low grade or subnephrotic proteinuria the diagnostic value of kidney biopsy as first-line diagnostics is less well established.

Methods

We conducted a retrospective analysis of all native kidney biopsies at our institution (n = 639) between 01/2012 and 05/2021 for comparison of histological diagnoses and clinical outcomes stratified by amount of proteinuria at the time of kidney biopsy: A: <300mg/g creatinine (low grade), B: 300-3500mg/g creatinine (subnephrotic), C >3500mg/g creatinine (nephrotic).

Results

Nephrotic range proteinuria was associated with the highest frequency (49.3%) of primary glomerulopathies followed by subnephrotic (34.4%) and low grade proteinuria (37.7%). However, within the subnephrotic group, the amount of proteinuria at kidney biopsy was linearly associated with renal and overall survival (HR 1.05 per Δ100mg protein/g creatinine (95% CI: 1.02–1.09, p = 0.001)) independent of present histological diagnoses and erythrocyturia.

Conclusion

Frequency of primary glomerulopathies supports to perform kidney biopsy in patients with subnephrotic proteinuria. These patients have a substantial risk of ESKD and death upon follow-up. Therefore, diagnostic accuracy including histopathology is essential to guide personalized treatment and avert detrimental courses.

Arteriolar hyalinosis and renal outcomes in patients with immunoglobulin A nephropathy

BACKGROUND

The relationship between arteriolar hyalinosis and renal progression in immunoglobulin A nephropathy (IgAN) is not fully understood. We aimed to investigate the clinicopathological features and outcomes of IgAN with or without arteriolar hyalinosis.

METHODS

A total of 762 diagnosed with IgAN patients were retrospectively analyzed. We classified IgAN patients into two groups with or without arteriolar hyalinosis. Then, the clinicopathological characteristics of the two groups were compared. We used Kaplan-Meier survival analysis to compare the composite kidney outcome of the two groups and applied multivariate Cox regression analyses to test the association between arteriolar hyalinosis and composite kidney outcome.

RESULTS

Overall, 412 (54.1%) patients had arteriolar hyalinosis, including 173 patients diagnosed with hypertension. IgAN patients with arteriolar hyalinosis were older and had higher proteinuria, urea, uric acid, and blood pressure, while lower eGFR than those without arteriolar hyalinosis. Subgroup analysis showed similar results in IgAN patients with hypertension. Kaplan-Meier survival analysis showed that IgAN patients with arteriolar hyalinosis had worse composite kidney outcome than those without arteriolar hyalinosis. In addition, subgroup analysis revealed that patients with hypertension have worse composite kidney outcome than those without hypertension. Multivariate Cox regression analyses confirm that arteriolar hyalinosis (HR 2.57; 95% CI 1.41-4.69; p = 0.002) is an independent risk factor for renal prognosis in IgAN patients.

CONCLUSIONS

Our study demonstrated that arteriolar hyalinosis is a common vascular lesion in IgAN patients. Arteriolar hyalinosis connects closely with hypertension, and arteriolar hyalinosis is an independent risk factor for renal prognosis in patients with IgAN.