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JUVENILE IDIOPATHIC ARTHRITIS

Introduction

Juvenile idiopathic arthritis (jia) is a chronic inflammatory condition defined by the International League of Associations for Rheumatology (ILAR) as arthritis that begins before the age of 16 years and persists for at least 6 weeks with exclusion of other known conditions.1 JIA is divided into systemic arthritis, oligoarthritis, polyarthritis, psoriatic arthritis, enthesitis-related arthritis, and undifferentiated arthritis (Table 60–1).2

Table 60–1Classification on Juvenile Idiopathic Arthritis

Epidemiology

In a systematic review, incidence rates varied from 1.6 to 23 per 100,000 persons and prevalence from 3.8 to 400 per 100,000 persons.3 Pooled incidence and prevalence were about doubled for girls.

Pathophysiology

Inflammation of the joints is thought to be related to polymorphisms in human leukocyte antigens that lead to antigen-activated T cells that release cytokines.4 This stimulates chondrocytes, osteoclasts, and fibroblasts to release metalloproteinases, leading to the erosion of bone and cartilage, synovial joint inflammation, and pannus formation.4

History and Physical Examination

In addition to a detailed history of joint pain, systemic features such as duration of fever, serositis, acute anterior uveitis, and lymphadenopathy are also important to ask about.4 A family medical history of psoriasis or rheumatologist conditions, especially ankylosing spondylitis, enthesitis-related arthritis, sacroiliitis with inflammatory bowel disease, Reiter's syndrome, and acute anterior uveitis, is particularly helpful.4,11

Objective: Laboratory Tests/Radiology

Laboratory Tests

Leukocytosis, thrombocytosis, and anemia are common in the condition.5 Inflammatory markers may be elevated, including the erythrocyte sedimentation rate (ESR), C-reactive protein, or ferritin. Rheumatoid factor (rarely seen in children younger than age 10),6 anti-cyclic citrullinated peptide antibodies, HLAB-27, and antinuclear antibody (ANA) ...

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