Anti Nuclear Antibodies (IFA)

Function

The Anti-Nuclear Antibody (ANA) test using Indirect Fluorescent Antibody (IFA) is the 'gold standard' screening tool for systemic autoimmune diseases. It detects antibodies that target the contents of the cell nucleus. The IFA method involves placing patient serum on a slide of human cells (HEp-2) and observing the patterns of fluorescence under a microscope.

Why it is Ordered

Physicians order an ANA test when a patient exhibits signs of a systemic autoimmune disorder, such as:

• Unexplained fever and persistent fatigue
• Joint pain and swelling (arthritis)
• A butterfly-shaped red rash across the cheeks and nose (malar rash)
• Sensitivity to sunlight and hair loss
• Numbness or color changes in fingers when cold (Raynaud's phenomenon)

Associated Conditions

A positive ANA is highly sensitive for Systemic Lupus Erythematosus (SLE), with over 95% of lupus patients testing positive. It is also associated with Scleroderma, Sjogren's Syndrome, Mixed Connective Tissue Disease (MCTD), and Autoimmune Hepatitis. It is important to note that a positive result is not a definitive diagnosis; it indicates that the immune system is active against self-tissues and requires further specific testing (like Anti-dsDNA or Anti-Smith).