From the Guidelines
A ferritin level of 100 μg/L in a patient with anti-MDA5 positive clinically amyopathic dermatomyositis (CADM) is considered low and requires close monitoring, as it may indicate a risk of developing rapidly progressive interstitial lung disease (RP-ILD), a potentially fatal complication. In the context of CADM, ferritin levels are often used as a biomarker for disease activity and risk of developing RP-ILD. While 100 μg/L falls within the normal reference range for the general population, patients with anti-MDA5 CADM who develop RP-ILD typically show significantly elevated ferritin levels (often >500-1000 μg/L) 1.
Key Considerations
- The presence of inflammation can affect ferritin levels, and a level of 100 μg/L may be considered low in the context of CADM, where inflammation is often present 1.
- The diagnosis of iron deficiency in patients with CADM can be complex, and ferritin levels should be interpreted in conjunction with other laboratory parameters, such as transferrin saturation and soluble transferrin receptor 1.
- Regular monitoring of ferritin levels, pulmonary function tests, and high-resolution CT scans of the chest should be performed every 1-2 weeks initially to assess disease activity and risk of RP-ILD.
Recommendations
- Implement aggressive immunosuppressive therapy, typically with a combination of high-dose corticosteroids (such as methylprednisolone 1000mg IV daily for 3 days followed by oral prednisone 1mg/kg/day), calcineurin inhibitors (tacrolimus or cyclosporine), and cyclophosphamide.
- Monitor ferritin levels closely, and any rising trend, even within normal range, may signal worsening disease activity.
- Consider the use of soluble transferrin receptor and reticulocyte hemoglobin content to assess iron status and guide therapy 1.
From the Research
Significance of Ferritin Level in CADM
- A ferritin level of 100 micrograms per liter in a patient with anti-MDA5 Clinically Amyopathic Dermatomyositis (CADM) may not be directly indicative of the disease's severity or prognosis, as the normal range for ferritin levels can vary 2, 3.
- However, high ferritin levels are generally associated with a poor prognosis and high mortality in patients with CADM and rapidly progressive interstitial lung disease (RP-ILD) 4, 5.
- The correlation between serum ferritin level and disease activity has been observed in some cases, suggesting that ferritin levels may be useful for monitoring clinical status 6.
- In some cases, patients with high anti-MDA5 antibody titers but not high ferritin levels may still experience a deterioration of their condition, highlighting the importance of considering intensive treatment regardless of the serum ferritin level 3.
Clinical Implications
- The presence of anti-MDA5 antibodies is associated with rapidly progressive interstitial lung disease, and early recognition of CADM can improve patients' prognosis 4, 5.
- Treatment with immunosuppressants and glucocorticoids may be effective in improving skin lesions and ILD, but relapse can occur when reducing the dose of prednisolone 2.
- Intensive treatment, including plasma exchange and calcineurin inhibitors, may be necessary for patients with high anti-MDA5 antibody titers, regardless of their ferritin levels 3.