Differential Diagnosis for Elevated Ferritin with REM Sleep Behavior Disorder

• Single Most Likely Diagnosis

  • Neurodegenerative disorders, specifically Parkinson's disease or Multiple System Atrophy: Elevated ferritin levels can be associated with neurodegenerative diseases, and REM sleep behavior disorder (RBD) is a known precursor to these conditions, particularly Parkinson's disease and multiple system atrophy. The presence of RBD significantly increases the likelihood of an underlying neurodegenerative process.

• Other Likely Diagnoses

  • Iron overload disorders (e.g., Hemochromatosis): While less directly linked to RBD, iron overload can lead to elevated ferritin levels. Although the primary presentation of hemochromatosis doesn't typically include RBD, it's a condition that could potentially contribute to neurological symptoms due to iron deposition in the brain.
  • Chronic inflammatory conditions: Certain chronic inflammatory diseases can cause elevated ferritin as an acute-phase reactant. While not directly linked to RBD, chronic inflammation can have widespread effects on the body, potentially influencing sleep patterns or contributing to neurodegenerative changes.

• Do Not Miss Diagnoses

  • Hemophagocytic Lymphohistiocytosis (HLH): A rare but life-threatening condition characterized by excessive immune activation, leading to elevated ferritin levels. Although HLH is not typically associated with RBD, its potential for rapid progression and high mortality rate make it a diagnosis that should not be missed, even in the absence of more typical presentations like fever, hepatosplenomegaly, and cytopenias.
  • Malignancies (e.g., lymphoma): Certain cancers can cause elevated ferritin levels. While RBD is not a common presenting symptom of malignancy, the diagnosis of cancer is critical due to its implications for treatment and prognosis.

• Rare Diagnoses

  • Pantothenate Kinase-Associated Neurodegeneration (PKAN): A rare genetic disorder characterized by iron accumulation in the brain, leading to neurological deterioration. It could potentially present with elevated ferritin levels and might have sleep disturbances, although RBD is not a commonly reported feature.
  • Aceruloplasminemia: A rare genetic disorder affecting iron metabolism, leading to iron accumulation in the brain and other organs. It could result in elevated ferritin levels and neurological symptoms, including potential sleep disturbances, although it is exceedingly rare and not typically associated with RBD.