Prevalence and immunopathologic characteristics of seropositive and seronegative hepatitis B virus-associated membranous nephropathy: a retrospective study of 420 biopsy-proven cases

Abstract

Background

This retrospective study aims to investigate the prevalence and immunopathologic characteristics of seropositive and seronegative hepatitis B virus-associated membranous nephropathy (HBV-MN).

Methods

Clinicopathologic and serologic records of 420 patients with histologically confirmed HBV-MN between January 2014 and July 2021 were examined to determine the prevalence of seropositive and seronegative HBV-MN. Serum anti-PLA2R antibody testing was conducted on 280 patients with HBV-associated membranous nephropathy (HBV-MN) from August 2018 to July 2021. Immunopathologic characteristics of HBV-MN patients and anti-PLA2R antibody positivity were analyzed.

Results

Among 420 pathologically confirmed HBV-MN patients, 230 (54.8%) were seropositive for HBV. The seropositive group exhibited higher blood creatinine values and incidence of liver function abnormalities than the seronegative group (p < .05). Serum anti-PLA2R antibody testing on 280 HBV-MN patients revealed a total positive rate of 44.6%, with the seronegative group showing a significantly higher rate (62.6%) compared to the seropositive group (32.1%) (p < .01). The anti-PLA2R antibody-positive group displayed higher levels of urine protein (p < .05), serum cholesterol (p < .01), and IgG4 subtypes (p < .05) compared to the negative group. Additionally, the positive group had significantly lower levels of serum albumin and IgG than the negative group (p < .01).

Conclusions

This comprehensive study reveals a significantly higher prevalence of seronegative HBV-MN than previously thought. The blood creatinine values and incidence of liver function abnormalities was higher in the serology-positive group than in the serology-negative group. Notably, the seronegative group displayed a higher positive rate of anti-PLA2R antibodies compared to the seropositive group, indicating distinctive clinical and immunopathologic features.

Keywords:

• Hepatitis B virus
• HBV-associated membranous nephropathy (HBV-MN)
• seroprevalence
• membranous nephropathy (MN)
• anti-phospholipase A2 receptor antibody

Introduction

The World Health Organization (WHO) estimates that approximately 2 billion people worldwide are infected with the hepatitis B virus (HBV), with 350 million of them having chronic infection [1]. In China, HBV remains the most common cause of liver disease and liver failure, with over 93 million individuals estimated to have chronic HBV infection, and one in five of them having chronic hepatitis B [2]. A recent seroepidemiological survey of approximately 150,000 individuals in China found a 7.70% (95% confidence interval [CI]: 7.57%–7.84%) positive rate for HBsAg, with a lower prevalence in children under 5 years old (0.77%) compared to adults (5.69%–11.22%). In contrast, the seroprevalence of HBsAg in other Asian countries, such as South Korea (4.0%) [3]and Singapore (3.6%, 95% CI: 2.9–4.2%) [4], is lower. In Europe, countries like the UK and the Netherlands report even lower seroprevalence rates for HBsAg, typically less than 1% [5].

Hepatitis B infection exhibits diverse clinical manifestations and can lead to liver failure. In China, extra-hepatic manifestations of hepatitis B, including HBV-associated glomerulonephritis (HBV-GN), have gained recognition. HBV-GN is now one of the most prevalent secondary glomerular diseases in China, accounting for 0.25% of renal biopsies [6,7]. Diagnosis of HBV-GN relies on positive HBV serum markers and the presence of HBV antigens in kidney biopsy specimens [8]. Zhang et al. utilizing renal biopsy data from 329 cases, demonstrated an association between serological HBV markers and renal pathological changes, with mesangioproliferative glomerulonephritis being the most common pathological subtype of HBV-GN [9]. However, renal biopsy is typically performed in patients with evidence of both renal damage and HBV infection, neglecting serum HBsAg-negative HBV-GN patients [10]. Kong et al. examined 500 glomerulonephritis patients without serological evidence of HBV infection and identified that 0.6% of these patients had occult HBV infection as shown by immunohistochemistry of frozen renal tissue specimens [11]. Li et al. conducted a study on 18 seronegative HBV-GN patients, highlighting that proteinuria was the predominant clinical manifestation, and renal histopathology predominantly displayed membranous nephropathy. This finding is consistent with an anecdotal report of 5 pediatric cases of HBsAg-negative HBV-GN, all of whom were diagnosed with membranous nephropathy [12].

The clinical utility of these findings is hindered by the limited sample size and anecdotal nature of previous studies on seronegative HBV-GN patients. Our prior investigation involving 196 cases of HBV-associated membranous nephropathy revealed some associations between clinicopathologic variables and HBV markers [13], though a definitive relationship was not established. In the present study, we conducted a retrospective review of the clinical, pathological, and serological data from 420 patients with pathologically confirmed HBV-MN. We aimed to assess the prevalence of seropositive and seronegative HBV-MN in this cohort and conducted an in-depth analysis of the immunopathologic characteristics of HBV-MN patients.

Patients and methods

Patients

We retrospectively analyzed clinicopathologic and serologic data from patients who underwent renal biopsy at China-Japan Friendship Hospital between January 2014 and July 2021. The diagnosis of HBV-GN was based on established criteria [14], including the presence of pathologically confirmed glomerulonephritis, with the exclusion of conditions such as lupus nephritis and other secondary nephritises. Diagnosis also required the presence of positive HBV antigens, specifically HBsAg or hepatitis B core antigen (HBcAg), as determined by immunohistochemistry in kidney tissue. Patients with available serological data on HBV antigens were included. Renal pathologic categories were classified according to the WHO Pathological Categories of Renal Glomerular Disease [15] (amended version), with two experienced pathologists (GZ and WZ) providing independent assessments.

Clinical data

Patient data obtained at the time of renal biopsy included age, sex, history of hepatitis B (documented or suspected), liver and kidney ultrasound results, as well as laboratory findings such as urinalysis, 24-h protein excretion, alanine aminotransferase (ALT), serum creatinine, and immunoglobulin levels. Serum HBV markers (HBsAg, HBeAg, HBsAb, HBeAb, and HBcAb) and HBV-DNA were determined using chemiluminescence immunoassay (CLIA) and real-time fluorescence quantitative polymerase chain reaction (RTFQ PCR). The estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI formula [16]. Renal function was classified into chronic kidney disease (CKD) stages 1–5 based on eGFR values [17]. CKD1: eGFR > 90 mL/min/1.73 m², CKD2: GFR 60–89 mL/min/1.73 m², CKD3: GFR 30–59 mL/min/1.73 m² (CKD3a: GFR 45–59 mL/min/1.73m², CKD3b: GFR 30–44 mL/min/1.73 m², CKD 4: GFR 15–29 mL/min/1.73 m², and CKD5: GFR < 15 mL/min/1.73 m² or dialysis.

Analysis of kidney biopsies

Percutaneous renal puncture was performed and kidney tissue specimens were obtained in 3 parts in all cases for light microscopy, immunofluorescence and electron microscopy. (1) Light microscopy: light microscopic specimens all contained more than 10 glomeruli, were paraffin-embedded, sectioned 2 μm thick, and stained with HE, PAS, PASM, and MASSON, respectively. (2) Immunofluorescence: Frozen sections were used to detect IgG, IgA, IgM, C3, C1q, FRA and IgG subclasses (IgG1, IgG2, IgG3 and IgG4) by direct immunofluorescence. (3) Electron microscopy: All kidney biopsy specimens were sent to the electron microscopy laboratory of China-Japan Friendship Hospital for examination. Renal pathological typing and diagnosis were referred to our pathological standards for renal biopsies^.

Serum testing for anti-PLA2R antibody

The patient’s serum was collected 1–3 d before renal biopsy and tested directly after collection with a human anti-phospholipase A2 receptor antibody enzyme immunoassay kit (Shanghai Lianshuo Biological), and each step was performed according to the instructions. Serum anti-PLA2R antibody ≥20 IU/ml was considered positive.

Statistical analysis

Statistical analysis was performed using the SPSS statistical software package, version 19.0 (SPSS Inc., Chicago, IL). Normally distributed variates were expressed as the mean ± SD, and continuous variates of unnormal distribution were expressed as the median with inter quartile range (IQR). Categorical variables were expressed as absolute values and percentages. For continuous variates, comparisons between two groups were performed using the Student’s t test for normally distributed data and the Wilcoxon rank-sum test for non parametric data; For categorical variables, Chi-square, Fisher exact test or Pearson Chi-square test were performed appropriately.

Results

Prevalence of seropositive and seronegative HBV-GN

The study flowchart, depicted in Figure 1, illustrates the patient selection process. Among 3364 patients who underwent renal biopsy at our institution during the study period, 3177 (94.4%) were diagnosed with pathologically-proven glomerulonephritis. Those without HBV in renal tissues and individuals lacking HBV-GN were excluded from the subsequent analysis. Ultimately, 420 (12.5%) patients with pathologically-proven HBV-MN were considered in this retrospective investigation.

Figure 1. The study flowchart. GN: glomerulonephritis; HBV, hepatitis B virus; MN: membranous nephropathy.

The distribution of serum HBV markers in patients with pathologically proven glomerulonephritis is detailed in Table 1. Out of the cohort, 230 (54.8%) patients were seropositive for HBV, including 29 (6.9%) who were HBsAg-positive. The remaining 190 (45.2%) were seronegative for HBV. HBV antigens were detected in renal tissue specimens from all 420 (100%) patients. Among them, 89 (21.2%) were positive for HBsAg, 28 (6.7%) for HBcAg, and 303 (72.1%) for both HBsAg and HBcAg. Immunohistochemical staining confirmed the presence of HBsAg and HBcAg antigens in the glomeruli, as depicted in Figure 2.

Figure 2. Detection of viral antigens and particles in renal tissues. Immunohistochemical staining of frozen renal tissue sections. (A) HBsAg and (B) HBcAg antigens are located in the glomeruli as indicated by brown staining in the glomeruli.

Table 1. Distribution of serum HBV markers among patients with pathologically proven glomerulonephritis (N = 420).

HBV markers
Seropositive, n(%)	230(54.8)
HBsAg, HBeAg, HBcAb (+)	16(3.8)
HBsAg, HBeAb, HBcAb (+)	13(3.1)
HBsAb, HBeAb, HBcAb (+)	38(9.1)
HBsAb (+)	73(17.4)
HBeAb, HBcAb (+)	47(11.2)
Others	43(10.2)
Seronegative, n(%)
HBsAg, HBeAg, HBsAb, HBeAb, HBcAb (−)	190(45.2)

Notes: HBV: hepatitis B virus; HBsAg: hepatitis B surface antigen; HBsAb: hepatitis B surface antibody; HBcAg: hepatitis B core antigen; HBcAb: hepatitis B core antibody; HBeAg: hepatitis B e antigen; HBeAb: hepatitis B e antibody.

Demographic and baseline characteristics of the study population

Table 2 summarizes the demographic and baseline characteristics of the study population. The mean age of the patients was 45.1 ± 15.6 years (range 14–82), with a slight male predominance (234, 55.7%). The median duration of HBV-MN was 7.76 months, ranging from 0.1 to 144. Hematuria was prevalent in the majority of patients (80.5%). The average 24-h urinary protein excretion was 4.73 ± 2.59 g/day, varying from 0.37 to 14.38, and around two-thirds (68.1%) had nephrotic syndrome. Additionally, most patients (84.5%) had CKD1. The blood creatinine values and incidence of liver function abnormalities was higher in the serology-positive group than in the serology-negative group.

Table 2. Demographic And baseline characteristics of the study subjects.

Variables	All	Seropositive HBV-MN	Seronegative HBV-MN	p
N	420	230	190	.35
Age, years
Mean (SD)	45.1(15.6)	46.4(16.1)	43.6(14.8)	.56
Range	14,82	14,79	14,82
Gender
Male	234(55.7%)	137(59.6%)	96(50.5%)	.64
Course of disease, months
Mean (SD)	7.76(15.17)	7.40(15.27)	7.45(14.32)	.95
Range	0.1, 144	0.2,144	0.1,120
24-h urinary protein excretion, g/day
Mean (SD)	4.73(2.59)	4.84(2.61)	4.61(2.44)	.34
Range	0.37,14.38	0.37,14.38	0.63,12.57
Serum creatinine(μmol/L)
Mean (SD)	67.1(26.1)	70.42(26.73)	63.63(21.68)	.008
Range	30,307	30,307	33,220
Hypertension, n(%)	144(34.3)	77(33.5)	67(35.3)	.70
Hematuria, n(%)	338(80.5)	182(79.1)	156(82.1)	.44
History of hepatitis B, n(%)	17(4.0)	17(7.4)	0
ALT > 40 U/L, n(%)	20(4.8)	16(7.0)	4(2.1)	.02
eGFR, mL/min/1.73 m^2
CKD1	355(84.5%)	188(81.7%)	167(87.9%)	.47
CKD2	45(10.7%)	28(12.2%)	17(8.9%)
CKD3a	13(3.1%)	9(3.91%)	4(2.1%)
CKD3b	3(0.7%)	2(0.9%)	1(0.5%)
CKD4	4(1.0%)	3(1.3%)	1(0.5%)
CKD5	0	0	0
Clinical manifestation^a
Nephrotic syndrome	286(68.1%)	159(69.1%)	127(66.8%)	.92
Chronic glomerulonephritis	129(30.7%)	68(29.6%)	61(32.1%)
Latent glomerulonephritis	4(1.0%)	2(0.9%)	2(1.1%)
Rapidly progressive glomerulonephritis	1(0.2%)	1(0.4%)	0

Notes: ALT: alanine aminotransferase; CKD: chronic kidney disease; eGFR: estimated glomerular filtration; MN: membranous nephropathy; HBV: hepatitis B virus.

^aNephrotic syndrome is a group of symptoms including protein in the urine (more than 3.5 g/24h), Low serum albumin levels(less than 30 g/L), high cholesterol levels, high triglyceride levels, and swelling. Chronic glomerulonephritis refers to proteinuria, hematuria, hypertension, edema as the basic clinical manifestations, the condition is prolonged, the lesion slowly progresses, can varying degrees of renal function decline; Latent glomerulonephritis, also known as asymptomatic proteinuria or hematuria, has abnormal urine routine examination findings, but no edema, hypertension or renal dysfunction such as performance. Rapidly progressive glomerulonephritis (RPGN) is a clinical and pathological syndrome; a term used to describe the following Rapid loss of renal function over a very short period (days to weeks). Nephritic urine analysis: proteinuria, micro or macroscopic hematuria, dysmorphic red blood cells (RBC), RBC casts. Histopathological characteristic on renal biopsy finding; cellular crescent formation in the glomeruli.

Immunopathologic characteristics of the study population

Table 3 displays the immunopathologic characteristics of the study population. All 420 subjects were diagnosed with membranous nephropathy, with the vast majority (93.3%) having uncomplicated membranous nephropathy. In the remaining 28 patients, membranous nephropathy was complicated by ischemic nephropathy in 13 patients, tubulointerstitial lesions in 9 patients, IgA nephropathy in 3 patients, obesity-associated nephropathy in 2 patients, and diabetic nephropathy in 1 patient. Among the 348 patients for whom IgG subtypes were determined at the time of biopsy, 96.0% were positive for IgG1, and 97.7% for IgG4. Approximately half (49.7%) were positive for IgG1, IgG2, and IgG4. Thirty-seven patients (10.6%) were positive for IgG1, IgG3, and IgG4, and one-fourth (25.6%) were positive for IgG1, IgG2, IgG3, and IgG4. Patients with seropositive and seronegative HBV-GN exhibited comparable immunopathologic characteristics.

Table 3. Pathological characteristics of the study population.

	All	Seropositive HBV-MN	Seronegative HBV-MN	p
Membranous nephropathy, n(%)	420(100)	230	190
Simple	392(93.3)	215(93.5)	177(93.2)	.90
Complicated	28(6.7)	15(6.5)	13(6.8)
ischemic nephropathy	13(3.1)	8(3.5)	5(2.6)
tubulointerstitial lesion	9(2.1)	6(2.6)	3(1.6)
IgA nephropathy	3(0.7)	1(0.4)	2(1.1)
obesity-related glomerulopathy	2(0.5)	0	2(1.1)
diabetic nephropathy	1(0.2)	0	1(0.5)
Immune fluorescence distribution of IgG subtypes, n(%)	348(100)	197	151
IgG1(+)	1(0.3)	1	0	.97
IgG2 or IgG3(+)	0(0)	0	0
IgG4(+)	7(2.0)	5	2
IgG1, IgG4(+)	34(9.8)	20	14
IgG1, IgG2, IgG4(+)	173(49.7)	99	74
IgG1, IgG3, IgG4(+)	37(10.6)	19	18
IgG1, IgG2, IgG3, IgG4(+)	89(25.6)	49	40
Others	7(2.0)	4	3

Notes: MN, membranous nephropathy; HBV, hepatitis B virus.

Positivity of anti-PLA2R antibodies in the study population

We conducted serum anti-PLA2R antibody testing on 280 patients from August 2018 to July 2021. Of the 165 patients in the seropositive HBV-MN group, 53 (32.1%) were positive for serum anti-PLA2R antibodies. In the seronegative HBV-MN group of 115 patients, 72 (62.6%) were positive for serum anti-PLA2R antibodies. The overall positive rate of anti-PLA2R antibodies in HBV-MN patients was 44.6%, and the seronegative group exhibited a significantly higher positivity rate compared to the seropositive group (p < .01).

Table 4. Comparative analysis of the clinicopathological data between the anti-PLA2R antibody-positive and negative groups.

Parameters	anti-PLA2R antibody-negative(n = 155)	anti-PLA2R antibody-positive(n = 125)	p
Age(years)	47.6 ± 14.9	48.4 ± 13.7	.616
Gender(male/%)	95(61.3%)	72(57.6%)	.532
Hematuria, n (%)	36(23.2%)	25(20.0%)	.516
Hypertension, n (%)	72(46.5%)	52(41.6%)	.417
Serum albumin (g/L)	30.2 ± 6.5	26.1 ± 4.3	<.001
Serum creatinine(μmol/L)	80.2 ± 29.1	78.3 ± 30.7	.752
eGFR (ml/min/1.73m^2)	96.8 ± 25.0	94.8 ± 23.9	.503
Proteinuria (g/24h)	5.7 ± 3.6	6.7 ± 3.3	.018
Uric acid(umol/L)	385.9 ± 96.2	375.6 ± 98.6	.419
Triglycerides (mmol/L)	2.6 ± 1.6	2.8 ± 2.0	.329
Cholesterol (mmol/L)	6.8 ± 2.0	8.1 ± 2.5	<.001
Serum-IgG (mg/dl)	751.9 ± 321.7	614.9 ± 230.1	<.001
Serum-IgM (mg/dl)	109.8 ± 54.2	111.4 ± 52.5	.791
Serum-IgA (mg/dl)	225.7 ± 104.6	225.8 ± 110.8	.995
Serum-C3 (mg/dl)	102.1 ± 22.9	99.8 ± 22.1	.387
Serum-C4 (mg/dl)	24.6 ± 7.2	25.5 ± 7.0	.270
IgG deposit, n (%)	152(98.1%)	124(99.2%)	.772
IgM deposit, n (%)	115(74.2%)	98(78.4%)	.412
IgA deposit, n (%)	141(91.1%)	115(92.0%)	.759
C3 deposit, n (%)	148(95.5%)	122(97.6%)	.343
C1q deposit, n (%)	142(91.6%)	114(91.2%)	.902
IgG1 deposit, n (%)	153(98.7%)	122(97.6%)	.487
IgG2 deposit, n (%)	132(85.2%)	97(77.6%)	.103
IgG3 deposit, n (%)	29(18.7%)	21(16.8%)	.678
IgG4 deposit, n (%)	142(91.6%)	123(98.4%)	.012

Note: The estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI formula [16].

Based on serum anti-PLA2R antibody levels, patients were categorized into two groups: negative (<20 IU/ml, n = 155) and positive (≥20 IU/ml, n = 125). The positive group displayed significantly higher levels of urine protein (p < .05) and serum cholesterol (p < .01) compared to the negative group. Furthermore, the positive group had significantly lower levels of serum albumin and IgG than the negative group (p < .01). The rate of IgG4 in renal tissue among patients with positive serum anti-PLA2R antibodies was significantly higher than that in the negative group (p < .05), with no significant difference in other IgG subclasses between the two groups (Table 4).

Discussion

HBV-GN is highly prevalent in China, constituting a common secondary glomerular disease among its population. Diagnosis traditionally relies on HBV seropositivity and the presence of HBV antigens in renal biopsy specimens, potentially leading to underdiagnosis. The recognition of seronegative HBV-GN’s importance is growing, yet current evidence remains limited, mainly derived from retrospective studies and anecdotal case reports [9–12].

In our study, we retrospectively analyzed a substantial cohort of 3364 patients who underwent renal biopsies over five years. Among these patients, a vast majority (94.4%) had pathologically-proven glomerulonephritis. Interestingly, 76.9% showed no evidence of HBV in renal tissues, while 420 (12.5%) were confirmed cases of HBV-MN. Among them, 230(54.8%) were seropositive for HBV, and 190 (45.2%) were seronegative for HBV. Our findings indicate that seronegative HBV-MN might be more prevalent than previously recognized, particularly when compared to Kong et al.’s study, where only 0.6% of 500 HBV-GN patients were found to have occult HBV infection [11].

The pathogenesis of HBV-GN remains incompletely understood. It is generally attributed to chronic HBV infection [18], leading to immune complex deposition in glomeruli [19]. In our study, both seropositive and seronegative HBV-MN patients exhibited renal tissue presence of HBV antigens and various IgG subtypes, indicating direct virally-induced pathological changes and ongoing immunological damage. Notably, IgG1 and IgG4 were nearly universally present in renal tissue specimens at the time of biopsy, suggesting widespread IgG subtype deposition in glomeruli.

Previous research by Zhou et al. also observed the presence of HBV-DNA in renal tissues, often coinciding with HBV antigen presence, suggesting potential local and systemic origins of these antigens, which contribute to cytopathologic damage and abnormal immune responses [20]. Our findings, demonstrating the presence of HBV antigens and IgG subtypes in seronegative HBV-MN patients, further support the notion of locally initiated immunological damage within the kidneys of HBV-MN patients.

Membranous nephropathy is the predominant manifestation of HBV-GN [21] and earlier studies have demonstrated the strongest association of HBV infection with membranous nephropathy [22–27], as observed in all 420 patients in our study. In adults, proteinuria and nephrotic syndrome are the primary clinical features of HBV-MN [28]. Our findings align with this pattern, as 95% of our HBV-MN patients presented with CKD1 and CKD2, indicating preserved renal function upon biopsy. Nevertheless, severe proteinuria, along with hematuria, was prevalent, and nephrotic syndrome developed in two-thirds of these patients.

We have shown that the prevalence of seronegative HBV-MN is similar to that of seropositive HBV-MN. The current diagnostic criteria for HBV-GN in China do not mandate HBV seropositivity. However, the strict criteria may leave a significant proportion of HBV-GN patients undiagnosed and untreated, particularly as HBV-GN accounts for a larger share of nephritis cases in China compared to regions with lower HBV infection rates like North America and Western Europe. Therefore, it is crucial to evaluate both serological HBV markers and HBV markers in renal tissues for patients with unexplained renal diseases, including membranous nephropathy.

Serum HBV-DNA >1*10³ IU/mL was observed in less than 4.6% of our patients. Unfortunately, we could not assess the correlation between serum HBV DNA levels and patient clinicopathologic variables. A study by Jiang and Liu [29] found a connection between renal injury and the replication level of HBV DNA in HBV-GN patients. They further demonstrated that a higher serum HBV DNA level was associated with increased deposition of HBV antigens in renal tissues and more progressive renal injury in HBV-GN patients [30]. This study is limited by its retrospective nature and lack of follow-up data. Additionally, our patient cohort is from a tertiary care center in China, which may not fully represent community care center settings.

In 2009, Beck [31] detected M-type PLA2R antibodies in the blood of idiopathic membranous nephropathy (IMN) patients, present in about 70–80% of IMN patients and strongly linked to disease activity and prognosis. These antibodies were not found in patients with secondary membranous nephropathy. Additionally, they observed that anti-PLA2R antibody titers correlated with disease activity, disappearing during remission and increasing upon recurrence [31,32].

Recent studies found positive anti-PLA2R antibodies in the serum of patients with atypical membranous nephropathy and HBV-MN [33–35]. Both IMN and HBV-MN patients had serum anti-PLA2R antibody expression, with no difference in the positive rate between these groups [36]. In our study, the total anti-PLA2R antibody positivity in HBV-MN patients was 44.6%, and the serology-negative group had a significantly higher positive rate compared to the serology-positive group (p < .01).

In conclusion, seronegative HBV-MN is more prevalent than previously believed and may equal seropositive HBV-MN in tertiary care settings in China. The blood creatinine values and incidence of liver function abnormalities was higher in the serology-positive group than in the serology-negative group. Notably, the serology-negative group displayed a significantly higher positive rate of anti-PLA2R antibodies compared to the seropositive group. While our study is the largest clinical cohort for HBV-MN, further confirmation through rigorous prospective studies is warranted.

Ethical approval

This study was approved by the Ethics Committee of China-Japan Friendship Hospital (approval number: 2019-17-K12)

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Elite Medical Professionals project of China-Japan Friendship Hospital (NO. ZRJY2021-BJ07). This work was supported by grants from college-level projects in the China-Japan Friendship Hospital, and we thank Guming Zou and Hongmei Gao for renal pathology sectioning and staining.