By using a highly sensitive serum M protein detection method based on the MALDI-TOF MS platform, serum monoclonal immunoglobul (M protein) in detection was performed on the visiting patients to explore the positive rate of serum M protein and its distribution in different departments. And exploring the correlation analysis between the relative concentration of serum M protein based on the above highly sensitive methods and clinical indicators.

Monoclonal gammopathy (MG) is an asymptomatic pre-cancerous clonal proliferation of plasma cells. The onset of this disease is concealed, usually discovered by chance by patients who undergo protein electrophoresis to detect monoclonal gamma globulin (M protein) due to various clinical symptoms and disease evaluations. Due to the insidious onset of monoclonal immunoglobulin, involving multiple organs, and the non-specific clinical symptoms, it is more prone to misdiagnosis. This study hypothesized that among patients who first came to the hospital for treatment, some patients had elevated serum monoclonal immunoglobulin levels but were not initially diagnosed with hematology department, but instead sought medical attention from other departments due to other symptoms. In this study，by using a highly sensitive serum M protein detection method based on the MALDI-TOF MS platform, serum monoclonal immunoglobul (M protein) in detection was performed on the visiting patients to explore the positive rate of serum M protein and its distribution in different departments，and to explore the correlation analysis between the relative concentration of serum M protein based on the above highly sensitive methods and clinical indicators.

Inclusion Criteria:

• Patients attending the outpatient/emergency/inpatient department of Zhujiang Hospital;
• Age: over 18 years old;
• There are sufficient remaining serum samples and extensive informed consent has been signed.

Exclusion Criteria:

• Early diagnosis of hematological diseases such as plasma cell or other B lymphocyte proliferative diseases；
• Improper storage or repeated freeze-thaw of remaining serum samples.

Patients over 18 years old attending the outpatient/emergency/inpatient departments of Zhujiang Hospital, including departments such as hematology, general surgery, dermatology, and others.