Assessment of ideal serum dilution for screening of antinuclear antibodies by an indirect immunofluorescence method in diagnosis of autoimmune disorders
| Autor: | S.K. Patnaik, Darshan S. Bhakuni, Arun Hegde, Aprajita Bhayana, Abhishek Kumar, Ashwini Kumar, Gautam Mullick, R. P. Singh, Krishnan Shanmuganandan, Vivek Vasdev |
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| Rok vydání: | 2022 |
| Předmět: |
musculoskeletal diseases
0301 basic medicine medicine.medical_specialty Indirect immunofluorescence Anti-nuclear antibody Receiver operating characteristic Serial dilution business.industry 030106 microbiology IIf General Medicine Gastroenterology stomatognathic diseases 03 medical and health sciences Titer 0302 clinical medicine Internal medicine medicine Original Article 030212 general & internal medicine CTD skin and connective tissue diseases business Serum dilution |
| Zdroj: | Med J Armed Forces India |
| ISSN: | 0377-1237 |
| DOI: | 10.1016/j.mjafi.2020.03.008 |
| Popis: | Background Time and cost constraints lead to majority of clinical laboratories deviating away from an ideal practice of checking for antinuclear antibodies (ANAs) by indirect immunofluorescence (IIF) at multiple dilutions. Usage of screening dilution of 1:40 recommended by most manufacturers of commercial ANA kits results in numerous false positive-tests and misdiagnosis of connective tissue disorders (CTDs). We sought to study the ideal screening dilution for ANA by IIF for a diagnosis of ANA-related CTDs. Methods Serum samples of patients with ANA-related conditions (n = 233) and healthy controls (n = 154) were evaluated by IIF using Immuno Concepts Hep-2000 ® ANA kits at dilutions from 1:40 to 1:640. Accuracy for diagnosis of CTDs for each serum dilution was assessed by receiver operating curve (ROC) analysis. Results Antinuclear antibodies (ANA) positivity was observed in 19.5%, 10.4%, 4.55%, 0.65%, and 0% of healthy controls at dilutions of 1:40, 1:80, 1:160, 1:320, and 1:640, respectively. ANA positivity at 1:40 dilution was observed among 26.4% cases with mimics of CTDs. Prevalence of ANA positivity in ANA-related CTDs was 97.3%, 96.4%, 89.3%, 83.9%, and 71.4% at dilutions of 1:40, 1:80, 1:160, 1:320, and 1:640, respectively. ROC analysis revealed best test performance for distinction between healthy and ANA-related CTD populations at a serum dilution of 1 in 80. Conclusions Antinuclear antibodies (ANA) positivity at low titers (1:40) is highly prevalent in healthy population (19.5%) as well as amongst mimics of CTD (26.4%). Our study suggests a higher screening dilution of 1:80 for ANA by IIF for diagnosis of CTD maybe better. Combination of 1:80 and 1:160 dilutions provides optimum sensitivity and specificity for diagnosis of ANA-related disorders. |
| Databáze: | OpenAIRE |
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