Background: Intravenous gamma-globulin treatment (IVGG) is an established therapy for acute phase Kawasaki disease (KD). Since a lot of studies have already testified that the efficacy of IVGG is dose-dependent, a single large dose of IVGG has been accepted as a standard treatment of KD. Some reports described the increasing rate of serum Immunoglobulin G (IgG) after IVGG would have a relationship with efficacy of IVGG. It should, therefore, be very important to compass trends of serum IgG levels in each in KD patient. However, it is unable to frequently measure values of serum IgG in KD patients from the standpoint of medical expenses. If we can estimate IgG levels in KD patients from routine biochemical data without additional costs, that is very helpful to assess inflammatory status in acute phase of KD.
Aim to this study: We hypothesized that serum levels of IgG in acute phase of KD patients could be extrapolated by serum values of total protein (TP) and albumin (Alb), and, we tried to establish a simple formula to estimate serum levels of IgG.
Materials and methods: We enrolled 42 KD cases (27 ± 21 month, Male 24/Female 18) that were treated in Saga University Hospital, Japan from April of 2010 to August of 2014. All cases met the diagnostic criteria of KD. They were initially treated with IVGG and aspirin or flurbiprofen. 12 patients (28.6%) needed additional treatments such as steroid and cyclosporine A. In this study, we examined relations before and after treatments of serum TP and Alb and IgG in serum of them and tried to establish a simple formula to estimate serum levels of IgG in acute phase of KD. For statistical analysis, we used paired t-test.
Results: We found that values obtained by subtracting serum values of IgG and Alb from TP were almost constant through acute phase in each KD patient, regardless of differences in clinical course and therapies. Therefore, we could estimate serum IgG values, once we checked levels of TP, Alb and IgG before treatment. Calculated IgG values were lineally correlated with values of directly measured IgG (P<0.0001, r=0.90). From this finding, we would assess the course of IgG levels during acute phase of KD patients correctly.
Conclusion: By estimation of IgG levels, we can grasp inflammatory status of KD and make appropriate therapeutic plans.