Review Question - QID 8443

The patient in Question 100 has a history most consistent with an infectious process such as osteomyelitis. Osteomyelitis most often presents acutely in children and is frequently associated with a precipitating minor trauma. For the patient in Question 101 these findings are more consistent with juvenile idiopathic arthritis. Complete blood count, erythrocyte sedimentation rate, and C-reactive protein labs are indicated as initial testing in inflammatory conditions, including infection and juvenile idiopathic arthritis. Unlike adults who have rheumatoid arthritis, children with juvenile idiopathic arthritis are not likely to have a positive rheumatoid factor and testing does not need to be routinely ordered. The patient in Question 102 has a history and examination suggestive of ankylosing spondylitis. HLA-B27 has 92% sensitivity and specificity for ankylosing spondylitis in European Americans and is present in 90% of affected individuals. Alkaline phosphatase, along with serum calcium, phosphorus, and vitamin D, are essential to screen for metabolic bone disorders, including rickets. The presentation of the child in Question 103 is most consistent with nutritional rickets. Although rare in the United States because multiple dietary supplements are easily accessible, nutritional rickets still occurs, most commonly in exclusively breastfed children (human breast milk does not provide significant vitamin D) who are dark skinned (vitamin D is synthesized in the skin from ultraviolet light exposure, and dark-skinned children absorb less UV light than light-skinned children). The patient in Question 104 has a history and examination suggestive of Lyme arthritis. Lyme disease is caused by the bacterium borrelia burgdorferi, which is transferred to humans through deer tick bites, most often in the Northeastern United States. Lyme arthritis usually presents as a relatively painless knee effusion. A titer for this organism, which is initially an enzyme-linked immunosorbent assay, is appropriate. Antinuclear antibodies are most commonly ordered when there is suspicion for systemic lupus erythematosis. Uric acid is most commonly ordered when there is suspicion for gouty arthritis.