Differential Diagnosis for Low Ferritin with Normal Hgb/Hct and Iron Studies

Single Most Likely Diagnosis

• Chronic Disease or Inflammation: A low ferritin level with normal hemoglobin (Hgb), hematocrit (Hct), and iron studies can often be seen in the context of chronic diseases or inflammation. Ferritin acts as an acute-phase reactant, and its levels can be low in chronic inflammatory conditions due to the body's prioritization of iron utilization for immune functions over storage.

Other Likely Diagnoses

• Early Iron Deficiency: Before Hgb and Hct levels drop, ferritin can be low, indicating depleted iron stores. This is a common condition, especially in menstruating women or individuals with increased iron demand.
• Pregnancy: Pregnancy increases the demand for iron, and ferritin levels can drop even if Hgb and Hct remain within normal limits due to the expansion of plasma volume.
• Vegetarian or Vegan Diet: Individuals on a strict vegetarian or vegan diet might have low ferritin due to lower intake of iron from animal sources, which is more readily absorbed than iron from plant sources.

Do Not Miss Diagnoses

• Hypothyroidism: Although less common, hypothyroidism can lead to decreased iron absorption and utilization, potentially resulting in low ferritin levels. Missing this diagnosis could lead to prolonged hypothyroidism with its associated complications.
• Celiac Disease: This autoimmune disorder can cause malabsorption of nutrients, including iron, leading to low ferritin levels. It's crucial not to miss this diagnosis due to its potential for long-term complications if left untreated.
• Chronic Kidney Disease (CKD): CKD can lead to disturbances in iron metabolism, and low ferritin can be an early sign. Missing CKD could result in progression to end-stage renal disease.

Rare Diagnoses

• Hemochromatosis with Inflammation: Although hemochromatosis typically presents with high ferritin, in the presence of inflammation, ferritin can be low due to its role as an acute-phase reactant. This is a rare scenario but could be considered in patients with a family history of hemochromatosis.
• Gaucher's Disease: A rare genetic disorder that can affect iron metabolism, potentially leading to low ferritin levels among other systemic manifestations.
• Neoplastic Conditions: Certain cancers can lead to abnormal iron metabolism, resulting in low ferritin levels. While rare, considering neoplastic conditions is important, especially in patients with unexplained weight loss, night sweats, or lymphadenopathy.