[Serum IgG4 levels in patients with ulcerative colitis, a predicting factor for primary sclerosing cholangitis?]

ABSTRACT

Primary sclerosing cholangitis [PSC] is a chronic cholestatic disease that results in segmental stenosis of the bile ducts, cholestasis and fibrosis. During the previous two decades, patients with steroid responsive PSC have been presented in a few case reports and studies. This study aims to evaluate and compare IgG4 levels in patients with ulcerative colitis [UC], with and without PSC. This cross-sectional study enrolled 116 patients with UC who referred to the Gastrointestinal Clinic of Imam Khomeini Hospital, Tehran, Iran. Patients with allergic diseases such as asthma and atopic dermatitis as well as those with autoimmune disorders such as vasculitis and systemic lupus erythmatosus were excluded. After signing an informed consent form, 5cc blood sample was taken for serum IgG4 evaluation. Patients with clinical or laboratory signs of PSC underwent Magnetic resonance cholangiopancreatography [MRCP] after which patients were divided into two groups [with and without PSC] according to the results of their MRCP findings. IgG levels more than 157 mg/dl were considered elevated. SPSS software package version 16 was used for data analysis. A significance level of 0.05 was considered statistically significant. There were 57[49.1%] male participants, of which 24 [20.7%] had evidence of PSC. Among these, 7 [29.1%] had elevated IgG4 titers. Of participants, 92 did not have PSC. From this group, 9 [9.7%] had elevated IgG4 levels. This difference was statistically significant [p =0.012]. The odds ratio was 3.9 [CI 1.28-12.1] and the area under the curve for IgG4 in predicting PSC in the ROC curve was 0.65. There was a significant relationship between IgG4 titer and colitis extension in both groups. However there was no significant relationship regarding the severity of colitis [p=0.247]. It is necessary to evaluate IgG4 titers in all patients with PSC because of its treatable nature. Determining IgG4 levels in all UC patients can be a predicting factor for PSC. Thus additional cohort studies with larger numbers of participants are recommended.