A comparison of antineutrophil cytoplasmic antibody prevalence in patients treated and untreated for hyperthyroidism

Challenges in diagnosis of limited granulomatosis with polyangiitis

Granulomatosis with polyangiitis (GPA) is an orphan disease with multifaceted clinical presentations and delayed diagnosis. Given the risks of delayed diagnosis and treatment, improving clinicians' awareness of atypical course of this disease is critically important. The aim of this report is to analyze a case of delayed diagnosis of GPA in view of similar publications. We analyzed articles retrieved from Scopus and MEDLINE/PubMed. The following keywords were used: "granulomatosis with polyangiitis", "Wegener granulomatosis", and "diagnostic errors". All case studies that fulfilled the Chapel Hill Consensus Conference and the American College of Rheumatology GPA criteria were retrieved. We report a 71-year-old female patient with a facial defect in the nasal region, nasal congestion, and serosanguineous discharge. Her final diagnosis of GPA was reached after a series of incorrect diagnoses in the past 40 years. A deforming facial lesion developed during this period of uncertainty and absence of appropriate treatment. This patient presented with atypical features of laboratory and instrumental examinations. Anti-neutrophil cytoplasmic antibodies (ANCA) were negative, while rheumatoid factor (RF; 46.3 IU/mL) and anti-citrullinated protein antibody (ACPA; 25.6 IU/mL) were elevated. The histological analysis of the nasal mucous membrane specimen did not indicate definite signs of vasculitis. However, it revealed a granuloma with aggregation of macrophages and massive infiltration of lymphocytes, ruling out previous diagnosis of carcinoma. We analyzed delayed diagnosis of GPA in our patient in the context of 12 previously reported similar cases of limited form of GPA. We emphasize the importance of histological examination for differential diagnosis of GPA.

The performance of the chemiluminescent immunoassay for measuring serum myeloperoxidase and proteinase 3 antibodies

Background

Enzyme‐linked immunosorbent assay (ELISA) has traditionally been used to detect myeloperoxidase (MPO) and proteinase 3 (PR3) antibodies, although it is time‐consuming and physically demanding. As a novel and highly effective immunoassay, we compared chemiluminescent immunoassay (CIA) with ELISA to verify the application value of CIA in MPO and PR3 antibodies detection.

Methods

By ELISA and CIA, serum levels of anti‐MPO and anti‐PR3 antibodies were measured in 63 anti‐neutrophil cytoplasmic antibody (ANCA)‐associated vasculitis (AAV) patients (AAV group), including 47 microscopic polyangiitis (MPA) patients and 16 granulomatosis with polyangiitis (GPA) patients, in addition, 68 patients in interference control group (IC group), 19 healthy subjects in healthy control group (HC group). We compared MPO and PR3 antibodies levels and positive rates measured by these two methods among groups. Relationship and coincidence rate between ELISA and CIA were investigated. Diagnostic values for clinical outcomes for MPO and PR3 antibodies were assessed by receiver operator characteristic (ROC) curve.

Results

In AAV patients, when detecting anti‐MPO (r = .90) and anti‐PR3 (r = .81), CIA was highly correlated with ELISA, companying with highly total (88.89%, 92.06%, respectively) and positive coincidence rates (84.78%, 77.27%, respectively). In HC group, anti‐PR3 positive rate detected by both immunoassay were 0, anti‐MPO almost were 0, which without statistically significant difference (P = .32). In IC group, the total (76.47%, 58.82, respectively) and positive coincidence rates (48.38%, 30.00%, respectively) of anti‐MPO and anti‐PR3 were the lowest, but the negative coincidence rates reached 100%. By CIA, similar to ELISA, the levels of anti‐MPO were significantly higher both in AAV patients (56.00; [4.40‐235.30]) and MPA patients (98.00; [27.90‐324.70]) compared with either IC group (3.20; [3.20‐18.55) (P < .0001) or HC group (3.20; [3.20‐3.20]) (P < .0001), yielded an area under curve (AUC) of 0.76 for AAV and 0.89 for MPA, the concentration of anti‐PR3 in GPA group (66.65; [24.43‐150.00]) was significantly higher than that in IC group (2.3; [2.3‐10.95]) (P < .0001) and HC group (2.3; [2.3‐2.3]) (P < .0001), with an AUC of 0.92.

Conclusion

Similar to ELISA, CIA was competent to detect MPO and PR3 antibodies in AAV patients and healthy population, thus distinguish AAV patients from IC group and HC group and effectively diagnose MPA and GPA.

The diagnostic role and clinical association of serum proteinase 3 anti-neutrophil cytoplasmic antibodies in Chinese patients with inflammatory bowel disease

Background and aim: Accurate differentiation of patients with ulcerative colitis (UC) or Crohn's disease (CD) is important for appropriate therapy and prognosis. This study was designed to explore the utility of proteinase 3 anti-neutrophil cytoplasmic antibodies (PR3-ANCA) in the diagnosis of Chinese patients with inflammatory bowel disease (IBD).Methods: Blood samples were collected from 216 Chinese patients, including 175 IBD and 41 colorectal polyps (disease control). Clinical characteristics were extracted from electronic medical records.Results: Serum PR3-ANCA were increased in UC patients compared to those with CD or colorectal polyps (p < .0001). PR3-ANCA was negative in colorectal polyps and there was no significant difference between CD and colorectal polyps (p > .05). Using the cut-off value of 20 chemiluminescent units (CU) provided by manufacturer, the positive rate of PR3-ANCA was higher in UC than CD (41.7% vs. 1.1%; p < .0001). Receiver operating characteristic (ROC) analysis demonstrated an area under the curve (AUC) of 0.89 (95% CI: 0.84-0.95; p < .0001) for differentiating UC from CD and suggested an optimized cutoff of 7.3 CU which improved sensitivity from 41.7% to 57.1%, while maintaining a specificity of 98.9%. PR3-ANCA in severe UC patients were higher than those with moderate UC (p < .05), no difference was found between those in remission or with mild or moderate activity (p > .05).Conclusions: Serum PR3-ANCA is a potentially useful clinical biomarker in Chinese patients with IBD. A modified cut-off value of 7.3 CU improves the performance for distinguishing UC from CD.

Development of anti-neutrophil cytoplasmic antibody-associated vasculitis in a patient with Graves' disease independent of anti-thyroid drug therapy

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) in patients with Graves' disease (GD) is linked with the use of anti-thyroid drugs (ATDs). We report the co-occurrence of AAV and GD in a patient that was independent of ATD therapy. A 38-year-old white male presented with systemic symptoms, palpitations, tremors, purpuric skin lesions, and digital pain. Physical examination and biological tests confirmed GD. He quickly developed multiple digital gangrenes and testicular pain/mass. Skin and testicular biopsies showed granulomatous vasculitis of the small- and medium-sized vessels, while his serum contained anti-proteinase-3 antibody.