Patterns of kidney diseases diagnosed by kidney biopsy and the impact of the COVID-19 pandemic in Yogyakarta, Indonesia: A single-center study

Abstract

BACKGROUND

Glomerular diseases rank third among the causes of chronic kidney disease worldwide and in Indonesia, and its burden continues to increase, especially regarding the sociodemographic index. Kidney biopsy remains the gold standard for the diagnosis and classification of glomerular diseases. It is crucial for developing treatment plans, determining the degree of histologic changes, and identifying disease relapse.

AIM

To describe the patterns of biopsy-proven kidney diseases in adult patients.

METHODS

We retrospectively reviewed the demographic, histopathologic, clinical, and laboratory data of 75 adult patients with biopsy-proven kidney diseases at our institution recorded from 2017 to 2022.

RESULTS

Among the patients, 43 (57.3%) were females, and the mean age was 31.52 years ± 11.70 years. The most common histopathologies were lupus nephritis (LN) (33.3%), minimal change disease (MCD) (26.7%), and focal segmental glomerulosclerosis (10.7%). LN (41.7%) was frequently diagnosed in women and MCD (28.1%) in men. The most common cause of nephritic syndrome was LN (36.7%) and of nephrotic syndrome was MCD (40%).

CONCLUSION

Different kidney disease patterns were observed in different sexes, age categories, clinical syndromes, and biopsy dates relative to the coronavirus disease 2019 pandemic.

Key Words: Kidney biopsy; Kidney diseases; Glomerular diseases; Epidemiology; Renal biopsy

Core Tip: This study retrospectively reviewed the demographic, histopathologic, clinical, and laboratory data of adult patients with biopsy-proven kidney diseases from 2017 to 2022. Different kidney disease patterns were observed in different sex, age categories, clinical syndromes, and biopsy dates relative to the coronavirus disease 2019 pandemic.

INTRODUCTION

Glomerular disease is the third most common cause of chronic kidney disease (CKD) worldwide, following diabetic nephropathy and hypertensive nephrosclerosis. The burden of CKD due to glomerular disease has increased globally, especially in regions and countries with lower sociodemographic indexes[1]. Similarly in Indonesia, glomerular diseases (10%) rank third among the causes of CKD, following hypertensive nephrosclerosis (36%) and diabetic nephropathy (28%)[2]. Glomerular diseases are associated with long-term morbidity and progression to end-stage kidney disease[3]. They are clinically critical because they can be reversed and successfully treated with early diagnosis and treatment[4].

Biopsy remains the gold standard for the diagnosis and classification of kidney diseases, especially glomerular diseases[5,6]. It is crucial for developing treatment plans, determining the degree of histologic changes, and identifying disease relapse. The degree of histologic changes is beneficial for predicting disease prognosis and response to therapy. Additionally, kidney biopsy can be used to assess genetic diseases[7].

Epidemiologic studies of kidney biopsy provide information about disease patterns and trends and insights into etiopathological aspects of kidney diseases and establish a foundation for future studies and public health policies. Integrating the data with renal replacement therapy registries allows the evaluation of long-term outcomes of patients with kidney diseases[8]. However, in Indonesia, epidemiologic studies describing the prevalence of biopsy-proven kidney diseases are lacking. Moreover, during the coronavirus disease 2019 (COVID-19) pandemic, there was a reduction in the frequency of and access to biopsy diagnostic procedures in general[9,10]. The present study aimed to describe the patterns of biopsy-proven kidney diseases and the impact of the COVID-19 pandemic on kidney biopsy procedures in adult patients at Dr. Sardjito General Hospital, a tertiary care center in Yogyakarta, Indonesia.

MATERIALS AND METHODS

Study design, subjects, and data collection

The patterns of kidney diseases of all adult patients diagnosed by kidney biopsy at Dr. Sardjito General Hospital in Yogyakarta, Indonesia, between 2017 and 2022 were retrospectively reviewed. Re-biopsies, incomplete records, inadequate biopsies, and graft biopsies were excluded. The age, sex, clinical syndrome, laboratory data at first presentation (i.e., urinalysis, blood urea nitrogen, creatinine, albumin levels, and lipid profiles), biopsy date, and kidney biopsy results and conclusions were recorded.

Kidney biopsy and glomerular disease classification

The indications for a kidney biopsy included microscopic hematuria and/or persistent proteinuria, nephrotic syndrome, acute nephritic syndrome, unexplained acute kidney injury, and suspected renal involvement in systemic diseases such as systemic lupus erythematosus (SLE) and anti-neutrophil cytoplasmic antibody-associated vasculitis. Percutaneous, ultrasound-guided core needle biopsies were performed in patients in prone position. Two kidney biopsy core specimens were extracted. The adequacy of the specimen, determined by the number of glomeruli, was confirmed by a pathologist. The specimens were divided into three pieces-for light, immunofluorescent, and electron-microscopic studies.

Primary glomerular diseases were classified into minimal change disease (MCD), immunoglobulin A (IgA) nephropathy (IgAN), membranous nephropathy (MN), focal segmental glomerulosclerosis (FSGS), global glomerulosclerosis, chronic glomerulonephritis, and glomerulopathy. Secondary glomerular diseases were categorized into lupus nephritis (LN), nephrosclerosis, post-streptococcal glomerulonephritis (PSGN), and tubulointerstitial nephritis (TIN).

Statistical analysis

Numerical data are presented as mean ± SD or median (interquartile range) and categorical data as frequency and percentage. The normality of data distribution was determined using the Shapiro–Wilk test. The mean difference was analyzed with the independent t-test or Mann–Whitney U test, whereas, the difference in proportion was evaluated using the chi-square test or Fisher’s exact test as appropriate. Analyses were performed with Statistical Package for the Social Sciences version 26.0 (IBM, United States). All graph figures were generated with MATLAB version 24.1.0.

Ethical considerations

This study was conducted according to the World Medical Association Declaration of Helsinki and was approved by the ethical committee of the institution (No. KE/FK/1902/EC/2003). Secondary data was used in this study.

RESULTS

Among 96 kidney biopsy records, only 75 were studied. Twenty-one records were excluded owing to inadequate biopsies (3) and incomplete data (18). The mean age of the patients was 31.52 years ± 11.70 years, ranging from 18 years to 59 years (males: 32.59 years ± 12.38 years; females: 30.72 years ± 11.25 years). Furthermore, 60% of the participants were ≥ 25 years old, and 43 of the 75 patients (57.3%) were females. The most common clinical syndrome at presentation was nephritic syndrome (80%). The most prevalent histopathologies between 2017 and 2022 were LN, MCD, and FSGS. Normal histopathology was encountered in two patients (2.7%). The total number of biopsies from before to after the COVID-19 pandemic increased, with a drastic reduction during the early pandemic (2020) (Figure 1). Table 1 summarizes the characteristics of all patients.

Figure 1 Trend of number of biopsies from 2017 to 2022 at Dr. Sardjito General Hospital.

Table 1 Characteristics of all patients (n = 75), n (%).

Variables	Frequency or mean ± SD (range)
Age	31.52 ± 11.70 (18-59)
Age category
18-24 years	30 (40.0)
≥ 25 years	45 (60.0)
Sex
Male	32 (42.7)
Female	43 (57.3)
Clinical syndrome
Nephritic syndrome	60 (80)
Nephrotic syndrome	15 (20)
Biopsy date
Before COVID-19 pandemic (2017-2019)	33 (44.0)
2017	1 (1.3)
2018	14 (18.7)
2019	18 (24.0)
During COVID-19 pandemic (2020-2022)	42 (56.0)
2020	1 (1.3)
2021	20 (26.7)
2022	21 (28.0)
Creatinine (mg/dL)	1.13 ± 0.73 (0.32-3.81)
Blood urea nitrogen (mg/dL)	19.40 ± 14.99 (5.10-80.70)
Epidermal growth factor receptor (mL/minute/1.73 m2)	99.59 ± 62.95 (14.32-369.77)
Albumin (g/dL)	2.75 ± 1.03 (1.03-4.92)
Lipid profile
Total cholesterol (mg/dL)	318.53 ± 150.48 (129-761)
Low-density lipoproteins cholesterol (mg/dL)	222.81 ± 125.08 (69-617)
high-density lipoprotein cholesterol (mg/dL)	54.36 ± 18.93 (23-130)
Triglyceride (mg/dL)	235.66 ± 124.20 (71-590)
Histopathology
Chronic glomerulonephritis	4 (5.3)
Focal segmental glomerulosclerosis	8 (10.7)
Global glomerulosclerosis	5 (6.7)
Glomerulopathy	3 (4.0)
IgA nephropathy	4 (5.3)
Lupus nephritis	25 (33.3)
Class I	3 (4.0)
Class II	4 (5.3)
Class III	7 (9.3)
Class IV	11 (14.7)
Minimal change disease	20 (26.7)
Nephrosclerosis	1 (1.3)
Post-streptococcal glomerulonephritis	1 (1.3)
Tubulointerstitial nephritis	2 (2.7)
Normal	2 (2.7)

COVID-19: Coronavirus disease 2019.

Histopathology results were stratified by sexes (Table 2, Figure 2A), age (Table 3, Figure 2B), clinical syndromes (Table 4, Figure 2C), and biopsy dates relative to the COVID-19 pandemic (Table 5, Figure 2D). When stratified by sex, LN was predominant in females, with a female-to-male ratio of 2.6:1. Moreover, no notable male predominance was observed in any histopathology diagnoses. However, these differences were not significant. The most prevalent diagnosis among female patients was LN (41.7%), whereas among males was MCD (28.1%).

Figure 2 Histopathology distribution. A: Sex; B: Age categories; C: Clinical syndromes; D: Biopsy dates. TIN: Tubulointerstitial nephritis; PSGN: Post-streptococcal glomerulonephritis; MCD: Minimal change disease; LN: Lupus nephritis; IgAN: Immunoglobulin A nephropathy; GGS: Gangliogliomas; FSGS: Focal segmental glomerulosclerosis; GN: Glomerulonephritis.

Table 2 Histopathology results stratified by sexes, n (%).

Histopathology	Female (n = 43)	Male (n = 32)	P value
Chronic glomerulonephritis	1 (2.3)	3 (9.4)	0.307
Focal segmental glomerulosclerosis	4 (9.3)	4 (12.5)	0.717
Global glomerulosclerosis	3 (7.0)	2 (6.3)	1.000
Glomerulopathy	1 (2.3)	2 (6.3)	0.572
Immunoglobulin A nephropathy	2 (4.7)	2 (6.3)	1.000
Lupus nephritis	18 (41.7)	7 (21.9)	0.069
Class I	2 (4.7)	1 (3.1)	0.805
Class II	2 (4.7)	2 (6.3)	1.000
Class III	6 (14.0)	1 (3.1)	0.227
Class IV	8 (18.6)	3 (9.4)	0.335
Minimal change disease	11 (25.6)	9 (28.1)	1.000
Nephrosclerosis	1 (2.3)	0 (0)	1.000
Post-streptococcal glomerulonephritis	1 (2.3)	0 (0)	1.000
Tubulointerstitial nephritis	1 (2.3)	1 (3.1)	1.000
Normal	0 (0)	2 (6.3)	0.179
Total	43 (57.3)	32 (42.7)

Table 3 Histopathology results stratified by age categories, n (%).

Histopathology	Age < 25 years old (n = 30)	Age ≥ 25 years old (n = 45)	P value
Chronic glomerulonephritis	0 (0)	4 (10.5)	0.145
Focal segmental glomerulosclerosis	3 (10.0)	5 (11.1)	1.000
Global glomerulosclerosis	1 (3.3)	4 (8.9)	0.642
Glomerulopathy	3 (10.0)	0 (0)	0.060
Immunoglobulin A nephropathy	1 (3.3)	3 (6.7)	0.646
Lupus nephritis	8 (26.7)	17 (37.8)	0.317
Class I	1 (3.3)	2 (4.4)	1.000
Class II	1 (3.3)	3 (6.7)	0.646
Class III	3 (10.0)	4 (8.9)	1.000
Class IV	3 (10.0)	8 (17.8)	0.509
Minimal change disease	11 (36.7)	9 (20.0)	0.110
Nephrosclerosis	1 (3.3)	0 (0)	0.400
Post-streptococcal glomerulonephritis	1 (3.3)	0 (0)	0.400
Tubulointerstitial nephritis	1 (3.3)	1 (2.2)	1.000
Normal	0 (0)	2 (4.4)	0.514
Total	30 (40)	45 (60)

Table 4 Histopathology results stratified by clinical syndromes, n (%).

Histopathology	Nephritic syndrome (n = 60)	Nephrotic syndrome (n = 15)	P value
Chronic glomerulonephritis	3 (5.0)	1 (6.7)	1.000
Focal segmental glomerulosclerosis	6 (10.0)	2 (13.3)	0.657
Global glomerulosclerosis	4 (6.7)	1 (6.7)	1.000
Glomerulopathy	3 (5.0)	0 (0)	1.000
Immunoglobulin A nephropathy	3 (5.0)	1 (6.7)	1.000
Lupus nephritis	22 (36.7)	3 (20)	0.221
Class I	3 (5.0)	0 (0)	1.000
Class II	4 (6.7)	0 (0)	0.578
Class III	5 (8.3)	2 (13.3)	0.622
Class IV	10 (16.7)	1 (6.7)	0.445
Minimal change disease	14 (23.3)	6 (40)	0.207
Nephrosclerosis	1 (1.7)	0 (0)	1.000
Post-streptococcal glomerulonephritis	1 (1.7)	0 (0)	1.000
Tubulointerstitial nephritis	2 (3.3)	0 (0)	1.000
Normal	1 (1.7)	1 (6.7)	0.362
Total	60 (80)	15 (20)

Table 5 Histopathology results stratified by biopsy dates relative to the coronavirus disease 2019 pandemic, n (%).

Histopathology	Before COVID-19 pandemic (n = 33)	During COVID-19 pandemic (n = 42)	P value
Chronic glomerulonephritis	0 (0)	4 (9.5)	0.126
Focal segmental glomerulosclerosis	4 (21.1)	4 (9.5)	0.725
Global glomerulosclerosis	4 (12.1)	1 (2.4)	0.163
Glomerulopathy	0 (0.0)	3 (7.1)	0.251
Immunoglobulin A nephropathy	2 (6.1)	2 (4.8)	1.000
Lupus nephritis	6 (18.2)	19 (45.2)	0.014
Class I	1 (3.0)	2 (4.8)	1.000
Class II	0 (0.0)	4 (9.5)	0.126
Class III	1 (3.0)	6 (14.3)	0.126
Class IV	4 (12.1)	7 (16.7)	0.746
Minimal change disease	14 (42.4)	6 (14.3)	0.006
Nephrosclerosis	1 (3.0)	0 (0.0)	0.440
Post-streptococcal glomerulonephritis	0 (0.0)	1 (2.4)	1.000
Tubulointerstitial nephritis	1 (3.0)	1 (2.4)	1.000
Normal	1 (3.0)	1 (2.4)	1.000
Total	33 (44.0)	42 (56.0)

COVID-19: Coronavirus disease 2019.

When stratified by age group, all glomerulopathy diagnoses (three patients) were observed among patients aged < 25 years, whereas all chronic glomerulonephritis (GN) diagnoses (four patients) were found in patients aged ≥ 25 years. MCD demonstrated a slight younger population predominance, with a ratio of 1.22:1 between patients aged < 25 years and ≥ 25 years. However, these differences were not significant. The most prevalent diagnosis among patients aged < 25 years was MCD (36.7%), whereas among those aged ≥ 25 years was LN (37.8%).

Stratification by clinical syndromes (nephritic vs nephrotic syndrome) demonstrated a predominance of nephritic syndrome in LN diagnoses, with a nephritic-to-nephrotic syndrome ratio of 7.33:1, and even more prominent in the most severe class (class IV) (10:1). Nephrotic syndrome was not predominant in the histopathology diagnoses. LN (36.7%) was the most common cause of nephritic syndrome, whereas MCD (40%) was the most frequent cause of nephrotic syndromes among this cohort.

Stratification by biopsy dates relative to the COVID-19 pandemic (2017–2019 and 2020–2022) showed significant differences in the number of LN [6 (18.2%) vs 19 (45.2%), P = 0.014] and MCD [14 (42.4%) vs 6 (14.3%), P = 0.006] diagnoses. MCD was more significantly prevalent before the COVID-19 pandemic and LN during the COVID-19 pandemic.

DISCUSSION

The present study presents an epidemiologic profile of all patients who underwent a kidney biopsy at Dr. Sardjito General Hospital, Yogyakarta, Indonesia, between 2017 and 2022. Ninety-six records of patients were obtained, among which only 75 were analyzed. Further, several epidemiologic trends, including age, sex, clinical syndrome, biopsy date relative to the COVID-19 pandemic, and histopathology, were described.

The mean age of the patients was 31.52 years ± 11.70 years (range: 18–59 years), indicating a relatively young age and the absence of elderly patients in this cohort. In younger patients, kidney diseases may often be attributed to congenital conditions, autoimmune diseases, genetic disorders, and idiopathic conditions[11]. For example, MCD, which is prominent in this cohort, is more common in younger individuals[12]. Moreover, in older patients, the etiology of kidney disease may shift toward chronic conditions, namely, hypertension, diabetes, and secondary effects of systemic diseases[13]. For instance, conditions such as LN and FSGS can develop in this age group. The cohort was approximately evenly divided into two categories: (1) Those aged < 30 years (49.3%); and (2) Those aged ≥ 30 years (50.7%). This balance indicates that kidney diseases requiring biopsy are equally prevalent among younger and older adults within this age range. The absence of geriatric population in this cohort may be due to the general reluctance[14] to perform kidney biopsy in elderly patients owing to the risk of complications (e.g., bleeding), unless the procedure provides maximal potential benefits for the patients[15,16].

The most prevalent clinical syndrome in the study cohort was nephritic syndrome (80%). The classification was made only into two syndromes, i.e., nephritic and nephrotic syndrome, because data was insufficient to make a more detailed classification. Nephritic syndrome often indicates an active, inflammatory process; hence, timely biopsy is critical for diagnosing specific types of glomerulonephritis and conducting appropriate treatment[17]. The urgency to identify conditions that underlie nephritic syndrome may have caused the higher biopsy rates among this population. In contrast, nephrotic syndrome may not always require immediate biopsy[18], especially if the clinical presentation indicates conditions such as MCD in children or young adults[19] or diabetic nephropathy in adults, wherein initial management can be performed without histological confirmation.

The number of biopsies increased from 33 patients before the COVID-19 pandemic (2017–2019) to 42 patients during the pandemic (2020–2022). A drastic decrease in the number of biopsies was observed early in the pandemic, i.e., only one procedure in 2020. During this time, several healthcare services were disrupted, and elective procedures were deferred. Additionally, patients may have avoided hospital visits because of fear of COVID-19 infection. A sudden increase of biopsies to 20 patients in 2021 was probably due to the resumption of the deferred healthcare services and the backlog of cases that accumulated in 2020. The healthcare system adapted to the pandemic, implementing protocols to safely conduct essential procedures such as kidney biopsies. A further increase to 21 patients in 2022 reflected continued adaptation and recovery of healthcare services. Similarly, a reduction followed by a backlog was observed in a population-based study on the impact of the COVID-19 pandemic on skin cancer diagnosis by skin biopsies[20] and on small biopsy procedures and cancer resection surgeries[9]. Understanding these patterns is crucial for improving future healthcare resilience and ensuring prompt diagnosis and management of kidney diseases during similar disruptions.

The most common histopathological diagnosis was LN, which was detected in 33.3% of patients. Class IV LN was the most prevalent (14.7%), followed by class III (9.3%), class II (5.3%), and class I (4.0%). MCD was the second most common diagnosis, accounting for 26.7% of cases. Other notable conditions included FSGS (10.7%), chronic glomerulonephritis (5.3%), and global glomerulosclerosis (6.7%). The less common diagnostic results were IgAN, glomerulopathy, nephrosclerosis, PSGN, TIN, and normal findings. The pattern in this cohort is not similar to the global epidemiologic patterns regarding kidney biopsies. The predominant kidney biopsy diagnoses in Japan were IgAN (39.2%), LN (6.5%), and MCD (6.0%)[21]. Moreover, in Central China, the most common primary glomerulonephritis in adults was MN (24.96%), followed by IgAN (24.09%) and MCD (10.71%). The most frequent secondary glomerulonephritis was LN (7.55%)[22]. In a single-center kidney biopsy 20-year review in South Korea, the predominant renal pathology diagnosed was mesangial proliferative GN (34.5%), followed by IgAN (33.3%) and membranous GN (8.8%)[23]. Among Vietnamese adult patients, the most common primary GN diagnoses were MCD (36.94%), FSGS (27.93%), and IgAN (20.72%), and the most common secondary GN diagnosis was LN (56%)[24]. This epidemiologic finding is relatively similar to the pattern in our cohort. The high prevalence of LN, particularly the more severe classes, underscores the importance of prompt and accurate diagnosis to treat these patients.

Histopathology diagnoses were stratified by sex, age, clinical syndromes, and biopsy dates relative to the COVID-19 pandemic. Upon stratification by sexes, LN was found to be more prevalent in females (41.7%) than in males (21.9%), showing a statistical significance (P = 0.069), associated with the higher incidence of SLE in women[25]. Severe classes (classes III and IV) of LN were found to be more common in females in our cohort, in contrast with reports of more clinically severe LN in men than in women in previous studies[26]. In stratifying by age categories, the present study used the cut-off age of 25 years to differentiate between young adults and older adults based on the World Health Organization classification[27]. Chronic glomerulonephritis, which progresses from prolonged acute GN[28], was observed only in patients aged ≥ 25 years, consistent with the fact that chronic GN will only become more apparent or is more frequently diagnosed in the older age group. The higher prevalence of MCD in patients aged < 25 years was associated with the known epidemiology of the disease, being more prevalent in children and young adults[12].

In this cohort, LN patients more frequently present with nephritic syndrome compared to nephrotic syndrome. The clinical presentation of LN varies from silent urinary abnormalities to highly symptomatic cases of nephritic syndrome or rapidly progressive renal insufficiency[29,30]. The pattern observed in the study cohort indicates that LN patients more frequently presented with an acute or severe condition, hence the higher incidence of nephritic syndrome. This is in contrast with that in the study by Moroni et al[31] evaluating the changing patterns in the clinical–histological presentation of LN patients, which showed that over the last decade, the frequency of renal insufficiency as LN presentation progressively decreased and that of isolated urinary abnormalities increased. Clinical presentation of LN, especially in developed countries, has become milder, which may be due to an earlier SLE diagnosis and sooner LN identification[29]. This reveals the importance of regular monitoring of renal function, 24-hour proteinuria, and urinary sediment in all SLE patients.

In the study cohort, MCD was more common in nephrotic syndrome, reflecting its clinical presentation with heavy proteinuria and minimal inflammation. This is consistent with global data, wherein MCD is a leading cause of nephrotic syndrome, particularly in children and young adults[12]. Other conditions in this cohort demonstrate similar prevalence across both clinical syndromes, which is inconsistent with existing epidemiologic data showing the predominance of nephrotic syndrome in FSGS[12] or nephritic syndrome in IgAN[32] and PSGN[33]. This may be due to the small number of patients with these conditions. Understanding the prevalence of kidney diseases in different clinical syndromes is beneficial for determining differential diagnoses and evaluating patients.

Upon stratification by biopsy dates relative to the start of the COVID-19 pandemic, two conditions, namely, LN and MCD, exhibited significant changes in the frequency of diagnoses. LN demonstrated a significant increase in diagnosis during the pandemic (P = 0.015). This increase may be due to an increased incidence of SLE flare-ups triggered by severe acute respiratory syndrome-coronavirus 2 infections. Viral infections trigger SLE or flares through molecular mimicry and epitope spreading[34,35]. Several case reports have described new SLE diagnoses and LN caused by COVID-19[36–40]. Moreover, COVID-19 has been associated with SLE flares[41]. This trend shows the need for close monitoring of SLE patients in periods of increased infection risk, such as during the COVID-19 pandemic. Furthermore, the significant decrease in MCD diagnoses may reflect the changes in healthcare-seeking behavior during the pandemic, with few non-urgent cases presenting for biopsy. These findings emphasize the importance of maintaining healthcare access for patients with kidney diseases during the pandemic and careful monitoring of chronic conditions that may be exacerbated by viral infections.

The strength of this study is that it provides insights on how the COVID-19 pandemic impacted the patterns of biopsy-proven kidney diseases. However, the limitations of this study are the relatively small sample size, which may limit the generalizability of the findings to larger populations; single-center setting, as the findings may only reflect regional healthcare practices and patient demographics; retrospective design, wherein this study relied only on existing records, which may have inconsistencies and potentially less accurate data; and presence of uncontrolled variables: Other factors, such as changes in healthcare policy, socioeconomic conditions, public health restrictions, and patient behaviors during the pandemic, were not controlled for and may have influenced the results. Future research with larger, multi-center cohorts and a prospective design is required to validate these findings and further explore the patterns observed.

CONCLUSION

The most common primary and secondary glomerular diseases at our institution were MCD and LN, respectively. Different kidney disease patterns were observed in different sexes, age groups, clinical syndromes, and biopsy dates in respect of the COVID-19 pandemic.

ACKNOWLEDGEMENTS

Authors express gratitude to the staff and residents of the Department of Anatomic Pathology, Universitas Gadjah Mada for providing the some of the data used in this study.