The goal of this observational study is to explore the factors that can predict the prognosis difference in patients with idiopathic membranous nephropathy (IMN) under the treatment of tacrolimus. The main questions it aims to answer are:

• to explore the factors that can predict the prognosis difference in patients with IMN under the treatment of tacrolimus
• to establish a clinical prediction model and verify it to provide a reference for the early Participants will receive standard the treatment of tacrolimus treatment and will then be divided into remission and non remission groups based on the treatment effect after the standard treatment cycle. Blood, urine, and fecal samples were collected from patients to explore possible factors influencing treatment efficacy.

Researchers will compare [remission group and non-remission group] to see if the gut microbiota and its metabolites are factors that influence the efficacy of treatment.

Inclusion Criteria:

1. Aged 18-75 years, the patient was diagnosed as idiopathic membranous nephropathy or anti phospholipase A2 receptor (PLA2R) antibody positive by renal puncture biopsy, and the clinical data were complete;
2. According to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines in 2020, it conforms to the medium and high risks in the risk level of progression of renal function loss.
3. In general, they are in good condition, have a good understanding of their own conditions and physical conditions, have self-awareness, and can communicate well with others;
4. Volunteer to participate in the study, understand the significance of this experiment and the indicators to be measured, and sign the informed consent form.

Exclusion Criteria:

1. There are factors causing secondary membranous nephropathy, such as immune diseases (systemic lupus erythematosus), tumors/infections (viral hepatitis), drugs or toxins;
2. At the same time, immunoglobulin A nephropathy (IgAN), interstitial nephritis, acute nephritis and other renal pathological types were combined;
3. The medication was not standardized during the treatment process, accompanied by serious infection, acute renal injury and other complications, and serious cardiovascular, cerebrovascular, digestive and blood system diseases;
4. During follow-up, the patient cannot actively cooperate or accurately understand and express.

Patients with idiopathic membranous nephropathy diagnosed at age 18-75 years