Pathological Staging of Primary Membranous Nephropathy

By performing examinations on the patients, the following indicators are included: albumin (ALB), total cholesterol (TC), triglycerides (TG), blood urea nitrogen (BUN), creatinine (CREA), estimated glomerular filtration rate (eGFR), urine specific gravity (urine SG), urine red blood cells (urine RBC), and proteinuria. In addition, renal biopsy is performed on the patients, based on the results of renal biopsy, patients are divided into two groups: patients diagnosed with PMN and patients without any signs of PMN. For patients in the PMN group, the inclusion criteria are as follows: (1) patients are included if they are diagnosed with PMN clinically, (2) patients are diagnosed with PMN by examinations. For the control group, patients who are evaluated without evidence of PMN based on examinations and medical records are included. The characteristics of the patient data are summarized in Table 6.Table 6

Data statistics

Status		Value
		ALB	TC	TG	BUN	CREA	eGFR	Urine SG	Urine RBC (HPF)	Proteinuria
Non-PMN
Maximum		48.100	7.160	8.280	10.800	92.300	132.400	1.035	5.600	1.000
Minimum		30.900	2.750	0.440	2.900	43.100	86.500	1.004	0.100	0.000
Mean		43.772	4.362	1.561	5.431	68.847	118.270	0.955	1.156	0.172
PMN
Maximum		44.700	19.310	19.810	11.300	100.000	152.000	1.055	101.700	4.000
Minimum		12.400	4.270	0.510	2.200	30.000	78.000	1.002	0.300	0.500
Mean		26.056	8.514	2.768	4.817	65.510	108.873	1.019	13.496	2.490

Based on the appearance of electron-dense deposits in glomerular basement membrane (GBM) in electron microscopy, PMN can be classified into 4 stages. During the initial stages, podocyte effacement is noted with minimal to no changes in the GBM (stage I). If the deposits persist, new basement membrane material is laid between these immune deposits giving rise to the spike formations identified on methenamine silver stains which are readily observed on electron microscopy (stage II). In stage III, these deposits are completely encircled by newly laid basement membrane. In more advanced stages, basement membranes are thickened, and the deposits become more lucent and the spikes become less apparent. Our patients included only stage I and stage II, According to the renal biopsy results, among all patients with PMN, 61 patients were diagnosed with stage I and 41 with stage II, and no patients with pathological stage III–IV. Moreover, there are several non-PMN patients included in this study to further validate our approach. The distribution of patients are listed in Table 7.Table 7

Distribution of patients

	Number of patients
Non-PMN	32
Stage I PMN	61
Stage II PMN	41