Can There Be a Negative ANA Test Result?
Yes, ANA can be negative in patients with autoimmune diseases, including 19-34% of autoimmune hepatitis cases and up to 49% of patients presenting with acute-on-chronic liver failure. 1
ANA Negativity in Autoimmune Hepatitis
Seronegative autoimmune hepatitis is a well-recognized entity, accounting for approximately 19-34% of all AIH cases despite patients being clinically and pathologically compatible with the disease. 1
Key Clinical Scenarios Where ANA is Negative:
Acute severe presentations: Among patients with acute severe AIH, 29-39% show negative or weakly positive ANA results, and 25-39% have normal serum IgG levels. 1
Acute-on-chronic liver failure (ACLF): The proportion of ANA-negative patients is as high as 49% in AIH patients presenting with ACLF. 1
Type 2 AIH: These patients characteristically have anti-LKM1 and/or anti-LC1 antibodies, usually with the absence of ANA and SMA. 1
Early disease stages: Approximately 20% of AIH patients may be negative for ANA, SMA, and anti-LKM1 even though they show clinical features of AIH. 1
Technical Factors Contributing to False Negatives
ELISA-based ANA testing can result in false negatives in about one-third of patients because ANA targets antigens whose specificity has not been determined. 1
Indirect immunofluorescence assay (IFA) using HEp-2 cells remains the reference standard for ANA detection. 1
Some specific autoantibodies (anti-Jo-1, anti-ribosomal P, or anti-SSA/Ro) may be present in patients who are ANA negative by IFA. 2
Different laboratories use different methods and cutoffs for ANA testing, affecting result interpretation. 2, 3
Diagnostic Approach for Suspected Autoimmune Disease with Negative ANA
When ANA is Negative but Clinical Suspicion Remains High:
Additional autoantibody testing should be performed regardless of ANA result, as recommended by the Korean Association for the Study of the Liver. 1
Test for Type 2 AIH markers: Anti-LKM1 and anti-LC1 antibodies should be ruled out. 1
Test for disease-specific antibodies: Anti-SLA (specific for AIH), which is found in 20-30% of AIH-1 and AIH-2 cases. 1
Consider p-ANCA testing: This can be detected as the only serological marker in 20-96% of suspected AIH-1 patients with negative ANA, SMA, and anti-SLA. 1
Liver biopsy is essential: Compatible histological findings showing portal lymphoplasmacytic infiltration, interface hepatitis, and plasma cells are critical for diagnosis when serology is negative. 1
Seroconversion During Follow-up:
Even if autoantibodies are negative at diagnosis, they can become positive later in the disease course. In retrospective studies, 60% of patients with autoantibody-negative AIH showed seroconversion up to 5 years of follow-up. 1
Clinical Implications and Management
A steroid trial for seronegative AIH is recommended when clinical and histological features are compatible with AIH despite negative autoantibodies. 1
The response to glucocorticoid treatment can be diagnostic in autoantibody-negative AIH. 1
Autoantibody-negative AIH shows lower serum IgG levels compared to autoantibody-positive AIH. 1
The frequency of advanced fibrosis and response to corticosteroids is similar between ANA-negative and ANA-positive AIH patients. 4
Common Pitfalls to Avoid
Do not exclude autoimmune disease based solely on negative ANA: Clinical suspicion, histology, and response to treatment are equally important diagnostic criteria. 1
Do not use ELISA as the sole method: Request IFA-based testing when clinical suspicion is high, as ELISA can miss up to one-third of positive cases. 1
Do not delay liver biopsy: In suspected AIH with negative serology, histological confirmation is essential and cannot be replaced by serological testing alone. 1
Consider referral to specialized laboratories: If diagnosis is uncertain, serological tests should be referred to a specialized reference laboratory for complete evaluation. 1