Objective:To compare the distribution differences of serum protein electrophoresis (SPE) among different gender and age individuals, and to explore the clinical application of SPE screening monoclonal gammopathy.Methods:A retrospective analysis was conducted based on the SPE results obtained from 533 989 cases enrolled from January 2018 to December 2019 at Zhongshan Hospital Affiliated to Fudan University. Among these patients, 435 479 inpatients were from departments of hematology, nephrology, spinal surgery, endocrinology, and rheumatology and immunology; and 98 510 were apparently healthy individuals. The distributions of albumin, α1 globulin, α2 globulin, β1 globulin, β2 globulin and γ globulin in different gender and age groups (≤20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, 81-90, ≥91 years old) were compared. A total of 10 014 cases were selected by immunofixation electrophoresis (IFE). The positive detection rates of different SPE bands and IFE bands were analyzed. The sensitivity and specificity of SPE methods were determined according to IFE results as the gold standard.Results:No significant difference was examined in the proportion of SPE bands between different genders ( P>0.05). There were statistically significant differences in the proportion of albumin bands between apparently healthy individuals and hospitalized patients at different ages (apparently healthy individuals: F=5.12, P<0.05, inpatients: F=4.18, P<0.05), and all of them decreased with the increase of age. The proportion of γ globulin bands increased with age (apparently healthy individuals: F=1.34, P<0.05; inpatients: F=1.24, P<0.05). The sensitivity of SPE was 69% (2 098/3 051), and the specificity was 97% (6 721/6 963). Compared with IFE method, the positive detection rate of monoclonal gammopathy was significantly different (χ2=5 049.94, P<0.05). The positive rate of monoclonal gammopathy in γ globulin region (21.11%, 2 114/10 014) was higher than that in β globulin region (3.28%, 328/10 014) (χ2=90.74, P<0.05) and β-γ globulin region (1.63%, 163/10 014) (χ2=44.34, P<0.05). IgG and IgM bands are common in γ globulin region. Among them, IgG-κ type accounted for 94.1% (995/1 058), IgG-λ type accounted for 94.8% (690/728), IgM-κ type accounted for 89.2% (222/249), IgM-λ accounted for 83.8% (62/74). IgA bands are common in β region, of which IgA-κ accounted for 49.8% (103/207) and IgA-λ accounted for 51.6% (149/289). The positive rate of monoclonal gammopathy of IgG-κ type was the highest (10.57%, 1 058/10 014), and the positive rate of monoclonal gammopathy of IgM-λ type was the lowest (0.74%, 74/10 014). Conclusions:With increasing age, the proportion of albumin band in SPE decreased and the proportion of γ globulin band increased. IgG and IgM type monoclonal gammopathy is mostly found in the gamma region, with a higher detection rate in IgG type. IgA type monoclonal gammopathy is mostly found in the β region, with a lower detection rate.

Objective:To investigate the characteristics and distribution of monoclonal gammopathy in clinical patients.Methods:A total of 936 171 patients (508 449 males and 427 722 females) who received capillary zone electrophoresis in Zhongshan Hospital Affiliated to Fudan University from January 2012 to December 2021 were selected, from which 14 945 patients with abnormal bands were screened as the study subjects, including 10 173 males and 4 772 females and the age 21-102 (65±13) years old. According to the age, patients were divided into 8 groups: 21-30 years old (168 cases), 31-40 years old (405 cases), 41-50 years old (1 326 cases), 51-60 years old (3 068 cases), 61-70 years old (4 985 cases), 71-80 years old (3 288 cases), 81-90 years old (1 519 cases), and≥91 years old (186 cases). The diagnostic results of the 14 945 patients with abnormal bands were collected and were divided into tumor group (5 196 cases) and non-tumor disease group (9 749 cases) according to the presence of tumor. The distribution of abnormal bands in different gender, age, and disease groups were retrospectively analyzed. Among the 14 945 patients, 4 988 cases underwent immunofixation electrophoresis, excluding 336 negative cases and 412 cases of double clonal bands reaction, and 4 240 patients with monoclonal immunoglobulin (M protein) reaction were selected as the study subjects, including 2 794 males and 1 446 females aged 21-102 (67±12) years old. They were divided into 8 groups according to the age: 21-30 years old (18 cases), 31-40 years old (91 cases), 41-50 years old (364 cases), 51-60 years old (862 cases), 61-70 years old (1 455 cases), 71-80 years old (904 cases), 81-90 years old (486 cases), and≥91 years old (60 cases). The diagnostic results and immunoglobin subtypes (IgA-κ, IgA-λ, IgG-κ, IgG-λ, IgM-κ, IgM-λ, κ, λ) of patients were collected, and the distribution of monoclonal gammopathy in different gender, age and disease groups were retrospectively analyzed.Results:Among 936 171 patients, 14 945 cases showed abnormal bands in electropherograms with a detection rate of 1.60%; the detection rates of abnormal bands in males and females were 2.00% (10 173/508 449) and 1.12% (4 772/427 722), respectively, with a statistically significant difference ( P<0.01). There was a significant difference in the detection rate of abnormal bands among different age groups ( P<0.01); among them, the highest detection rate of abnormal band in group of ≥91 years old was 5.98%, and the ratio of male to female was 1.67∶1. Among the 14 945 cases of abnormal bands, patients aged 51-60, 61-70 and 71-80 accounted for 20.53% (3 068 cases), 33.36% (4 985 cases) and 22.00% (3 288 cases), respectively, and the differences among the age groups were statistically significant (χ 2=115.82, P<0.01). In the tumor group, the top 3 tumors with abnormal bands were plasmacytoma with 1 123 cases, lymphoma with 289 cases, and leukemia with 49 cases. The detection rate of abnormal bands in electropherograms of plasmacytoma was 89.92% (1 123/1 249), which was higher than that in lymphoma and leukemia [6.73% (289/4 296) and 6.40% (49/766), respectively, P<0.01]. Among 4 240 patients with positive M protein, the proportion of 51-60, 61-70 and 71-80 years old patients were 20.33% (862/4 240), 34.32% (1 455/4 240) and 21.32% (904/4 240), respectively, and the differences among age groups were statistically significant ( P<0.01). The results of M protein types showed that the proportion of IgG-κ type was the highest in both genders, with 32.28% (902/2 794) in males and 34.30% (496/1 446) in females. In the 21-30, 31-40, and 41-50 age groups, the proportion of IgG-λ was the highest, which were 38.89% (7/18), 36.26% (33/91) and 34.07% (124/364) in these groups respectively. However, the proportions of IgG-κ were the highest in either of the 51-60, 61-70, 71-80, 81-90 and ≥91 years old groups, which were 33.87% (292/862), 34.16% (497/1 455), 31.53% (285/904), 34.57% (168/486), 28.33% (17/60), respectively, and the differences among all age groups and gender groups had statistical significance ( P<0.01). Among patients with positive M protein in the tumor group, plasmacytoma accounted for 14.22% (603/4 240), followed by lymphoma 6.30% (267/4 240); among non-tumor diseases, M proteinemia accounted for the highest proportion (7.24%, 307/4 240), followed by pulmonary infection (5.47%, 232/4 240). Conclusions:The detection rate of abnormal bands in capillary zone electrophoresis may increase with age, and is higher in males than in females in the same age group; different malignant tumor diseases can also show abnormal bands in capillary zone electrophoresis, but they are still mainly hematological tumors. Among the positive results of M protein, 61-70 years old group accounts for the highest proportion; the most common type of monoclonal gammopathy is IgG type; in the age group of 21-50 years, the proportion of IgG-λ type is the highest; in the group of >50 years old, the proportion of IgG-κ type is the highest; in the diagnosis of positive monoclonal gammopathy, the top 3 diseases are all hematological diseases, including plasmacytoma, monoclonal gammopathies and lymphoma.