Assessing the Clinical Utility of Antinuclear Antibody Titer Dilutions, Antinuclear Antibody Staining Patterns, and Other Common Laboratory Tests in Juvenile Idiopathic Arthritis.

Chronic musculoskeletal pain in pediatric patients can be challenging to diagnose, particularly in the absence of overt signs of autoimmune disease, as these episodes can manifest episodically. We present a case of a 14-year-old female patient with a two-year history of episodic "bone pain," morning stiffness, and infrequent fever and fatigue. Laboratory testing revealed an antinuclear antibody (ANA) titer of 1:1280 with a nuclear homogeneous pattern and a mildly elevated erythrocyte sedimentation rate (ESR). Although the patient did not meet the criteria for juvenile idiopathic arthritis (JIA), her laboratory findings and irregular musculoskeletal pain prompted the review of literature on the diagnostic value of ANA titers, ANA staining patterns, and other common lab tests in JIA.