“In a patient failing to respond [to allopurinol], consider checking an oxypurinol level,” Dr. Kolfenbach said. Previous analysis in clinical trials of allopurinol has demonstrated that plasma oxypurinol can be used as an effective measure of adherence.2
Pediatric Pearls
10. Dr. Stone reviewed several pearls related to pediatric rheumatology. First, myositis-specific antibodies in juvenile dermatomyositis have different phenotypes than in adults.
Second, he explained that checking a ferritin-to-erythrocyte sedimentation rate (ESR) ratio can help distinguish systemic juvenile idiopathic arthritis (JIA) flares from macrophage activation syndrome (MAS); a ferritin:ESR ratio >21.5 strongly suggests MAS in the setting of JIA.
“This occurs due to the rapid rise of ferritin and decline in ESR due to fibrinogen consumption during MAS,” Dr. Stone said.
Mithu Maheswaranathan, MD, completed his fellowship in rheumatology at Duke University, Durham, N.C., where he is currently a clinical instructor in the Division of Rheumatology and Immunology. He can be contacted on Twitter (@MithuRheum).
References
- Ghiasi M. Strawberry gingivitis in granulomatosis with polyangiitis. N Engl J Med. 2017 Nov 23;377(21):2073.
- Stamp LK, Merriman T, Frampton C, et al. Plasma oxypurinol as a measure of adherence in clinical trials. Ann Rheum Dis. 2018; 77(2):313–314.
