400
A 10 year old girl with known systemic onset JIA for 4 years presents with acute bloody nose, and these lab values: ALT 890, AST 799, + D-dimer, PTT prolonged at 100 sec, EBC 2k, plt 45k, ESR 8, and ferritin 2,200.
Macrophage Activation Syndrome (MAS)
Occurs with sever systemic onset JIA. MAS is also known as hemophagocytic syndrome. Bone marrow may reveal hemophagocytosis. The lab findings of markedly elevated transaminases, with a positive D-dimer, prolonged PTT, and cytopenias are classic. ESR is classically depressed as well in contrast to the severity of the disease process due to the low fibrinogen.