To explore the relationship between serum β2 microglobulin and the lesion of focal segmental glomerulosclerosis (FSGS) in patients with idiopathic membranous nephropathy (IMN).

This study was a single-center retrospective cross-sectional research. According to the criteria for inclusion and exclusion, 152 patients, who were hospitalized at Hechi People′s Hospital and diagnosed with IMN by renal biopsy, were included. According to the presence or absence of FSGS lesion, the patients were divided into FSGS group and non-FSGS group. The differences in demographic, biochemical, and pathological indicators between the two groups were compared. The correlation between serum β2 microglobulin and renal interstitial lesion score or the proportion of FSGS lesion was analyzed. Multivariate logistic regression analysis was used to explore the relationship between serum β2 microglobulin and the FSGS lesion. The generalized additive model (GAM) was used to explore the nonlinear relationship between serum β2 microglobulin and the FSGS lesion. In addition, the relationship between serum β2 microglobulin and the FSGS lesion in different subgroups was also analyzed.

After adjusting the factors including gender, age, ethnicity, occupation, course of disease, history of hypertension, diabetes, body mass index (BMI), 24 h urine protein, microscopic hematuria, blood hemoglobin, lymphocytes, albumin, globulin, fasting blood glucose, uric acid, triglycerides, high density lipoprotein, and renal interstitial atrophy and fibrosis, the multivariate logistic regression analysis showed that serum β2 microglobulin was an independent risk factor for the occurrence of FSGS lesion (OR 1.421, 95%CI: 1.002-2.014, P=0.049). GAM analysis found that the relationship between serum β2 microglobulin and the FSGS lesion was linear. The results of subgroup analysis suggested that the relationship between serum β2 microglobulin and the FSGS lesion was enhanced in patients with a history of hypertension (OR 4.086, 95%CI: 1.512-11.043), but not in patients without a history of hypertension (OR 1.007, 95%CI: 0.647-1.567) (P=0.975). ROC curve analysis showed that serum β2 microglobulin might be of value in diagnosing the occurrence of FSGS lesion (AUC=0.668), and the best cut-off value was 2.65 mg/L. It was found that compared with IMN patients without a history of hypertension and the serum β2 microglobulin <2.65 mg/L, the occurrence risk of FSGS lesion increased by 3.7 times (OR 4.711, 95%CI: 1.732-12.812, P=0.002) in patients with both a history of hypertension and the serum β2 microglobulin ≥2.65 mg/L.

The increase of serum β2 microglobulin was closely related to FSGS lesion occurrence in IMN patients. In patients with a history of hypertension the influence of serum β2 microglobulin on FSGS lesion occurrence was enhanced.