title: Elevated serum IgG4 levels in diagnosis and treatment response in patients with idiopathic retroperitoneal fibrosis.
abstract: Idiopathic retroperitoneal fibrosis (iRPF) may be a manifestation of IgG4-related disease. Measuring serum IgG4 (sIgG4) may be of value in monitoring iRPF, but this has scarcely been evaluated. It is unknown if tamoxifen (TMX) affects sIgG4 levels. We performed a prospective inception cohort study of 59 patients with untreated (re)active iRPF stratified by elevated (>1.4 g/L) or normal sIgG4 level. Changes in sIgG4 levels following TMX initiation and, if treatment failed, during subsequent corticosteroid (CS) treatment were analyzed. The median sIgG4 level was 1.1 g/L (interquartile range (IQR) 0.4-2.2); 24 patients (40%) had elevated sIgG4 level. Patients with elevated sIgG4 tended to present with higher ESR (46 vs. 34 mm/h; P = 0.08) and more frequent locoregional lymphadenopathy adjacent to the mass (41.7 vs. 20.0%; P = 0.08). sIgG4 also correlated with ESR (ρ = 0.26; P = 0.05) and serum creatinine (SC) (ρ = 0.26; P = 0.04). Following TMX initiation, sIgG4 level decreased, particularly when achieving treatment success (P < 0.01). Odds ratio for TMX treatment success in patients with elevated sIgG4 level was 0.77 (95% CI 0.53-1.14; P = 0.19). After adjusting for age, sex, and SC, the odds ratio was 0.78 (95% CI 0.51-1.18; P = 0.24). ROC curve analyses of sIgG4 on a continuous scale and treatment success showed an AUC of 0.62. Treatment success and concurrent sIgG4 decrease (P < 0.01) were achieved in 78% of patients who converted to CS therapy. Patients with elevated sIgG4 level may be more inflammatory than patients with normal sIgG4 level, but this needs further study. TMX affects sIgG4 levels, but to a lesser extent than CSs. sIgG4 cannot be used as an outcome prediction tool, irrespective of which cutoff value was chosen.
authors.affiliation: Department of Internal Medicine, Albert Schweitzer Hospital, Dordrecht, The Netherlands.|National Center of Expertise Retroperitoneal Fibrosis, Albert Schweitzer Hospital, PO Box 444, NL-3300 AK, Dordrecht, The Netherlands.
authors.forename: L G
authors.initials: LG
authors.lastname: Pelkmans
authors.affiliation: Department of Radiology, Albert Schweitzer Hospital, Dordrecht, The Netherlands.
authors.forename: T R
authors.initials: TR
authors.lastname: Hendriksz
authors.affiliation: Department of Pathology, Albert Schweitzer Hospital, Dordrecht, The Netherlands.
authors.forename: P J
authors.initials: PJ
authors.lastname: Westenend
authors.affiliation: Result Laboratory, Albert Schweitzer Hospital, Dordrecht, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Vermeer
authors.affiliation: Department of Internal Medicine, Albert Schweitzer Hospital, Dordrecht, The Netherlands. e.f.h.vanbommel@asz.nl.|National Center of Expertise Retroperitoneal Fibrosis, Albert Schweitzer Hospital, PO Box 444, NL-3300 AK, Dordrecht, The Netherlands. e.f.h.vanbommel@asz.nl.
authors.forename: E F H
authors.initials: EFH
authors.lastname: van Bommel
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009426:Netherlands; D011379:Prognosis; D011446:Prospective Studies; D012372:ROC Curve; D012185:Retroperitoneal Fibrosis / Q000097:blood / Q000000981:diagnostic imaging / Q000188:drug therapy*; D013629:Tamoxifen / Q000627:therapeutic use*; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure
chemical_list: D000305:Adrenal Cortex Hormones; D007074:Immunoglobulin G; D013629:Tamoxifen
keywords: Corticosteroids; IgG4; Retroperitoneal fibrosis; Tamoxifen