How is macrophage activation syndrome (MAS) diagnosed in patients with systemic lupus erythematosus (SLE)?

Updated: Nov 21, 2018
  • Author: Angelo Ravelli, MD; Chief Editor: Lawrence K Jung, MD  more...
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As previously reported, diagnosis of macrophage activation syndrome may be particularly challenging in patients with systemic lupus erythematosus (SLE) because it may mimic the clinical and laboratory features of the underlying disease. Recently, preliminary diagnostic guidelines for macrophage activation syndrome complicating juvenile SLE were developed. [38]

The main laboratory findings of macrophage activation syndrome include the following:

  • Cytopenias

  • Abnormal serum hepatic enzyme levels

  • Coagulopathy

  • Decreased erythrocyte sedimentation rate

  • Hypertriglyceridemia

  • Hyponatremia

  • Hypoalbuminemia

  • Hyperferritinemia

The initial laboratory evaluation should include the following:

  • CBC count with platelets and reticulocyte count

  • Acute phase reactants (ie, erythrocyte sedimentation rate and C-reactive protein [CRP] levels)

  • Markers of liver and kidney function

  • Ferritin levels: Hyperferritinemia is an important laboratory hallmark of macrophage activation syndrome that has received increasing attention; elevated ferritin levels (often >10,000 ng/mL) have been reported in the acute phase of macrophage activation syndrome. Furthermore, a good correlation between ferritin levels and response to therapy has been observed; a decrease in ferritin levels is associated with a favorable course of macrophage activation syndrome. Recent studies have shown that low levels of glycosylated ferritin, in the presence of high level of total serum ferritin, may be another helpful marker for diagnosis. [39, 40]  A retrospective analysis by Ruscitti et al that included 50 Still’s disease patients (21 pediatric and 29 adult) reported that at diagnosis, high levels of serum ferritin and an elevated systemic score were associated with MAS. [41]  

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