The laboratory differential diagnosis of Henoch-Schonlein purpura / 中华检验医学杂志

ABSTRACT

Objective To explore the common clinical features and mechanism of HenochSchonlein purpura (HSP) in children,and provide evidence and guidance for clinical diagnosis,therapy and prognosis of HSP.Methods Prospective study.Totally 1 232 HSP children blood samples were collected during January 2010 to December 2013 in the Children's Hospital of Zhejiang University School of Medicine,and the levels of immunoglobulin,complement,T lymphocyte subsets and CRP were detected in the acute phase of HSP.The clinical data were analyzed with these indexes to explore the function of cellular and/or humoral immunity in the pathogenesis of HSP.In addition,this study detected serum IgA levels in 200 cases of sepsis rash,200 cases of urticarial and 200 cases of thrombocytopenic purpura patients and 400 cases of healthy children over the same period to our hospital respectively,in order to find out whether IgA is capable of differentiating allergic purpura rash from other similar skin rashes.Results Compared with healthy children,the IgA level was significantly higher [IgA2.0 (0.6-7.5) g/L vs 1.1(0.6-2.1) g/L,Z =5.928,P =0.03].When IgA ＞ 1.44 g/L,the diagnostic sensitivity and specificity to differentiate allergic purpura patients from sepsis patients were 77.43 ％ (954/1 232) and 80.00％ (160/200),respectively.When IgA ＞ 1.53 g/L,the diagnostic sensitivity and specificity to distinguish from allergic purpura with urticaria patients were 72.57％ (894/1 232) and 74.51％ (149/200).When IgA ＞0.91 g/L,it had a 95.14％ sensitivity (1 172/1 232) and a 79.45％ specificity (159/200) for the differential diagnosis of allergic purpura and thrombocytopenic purpura patients.When IgA ＞ 1.33 g/L,the sensitivity of distinguishing allergic purpura patients from healthy children was 81.25％ (1 001/1 232),while the specificity was 95.00％ (380/400).Conclusions HSP children show cellular immune dysfunction.Th1/Th2 imbalance and over-activation of Th2 cells result in the increased synthesis and release of immune globulin,causing abnormalities in humoral immune.An increase in serum IgA level of HSP patients can differentiate HSP from other similar rashes.