Differential Diagnosis for Low Ferritin with Normal Iron Studies

The patient's laboratory results show a low ferritin level of 16, despite having normal iron, normal iron binding capacity, and normal percent saturation of iron. Here's a differential diagnosis, categorized for clarity:

• Single Most Likely Diagnosis

  • Chronic Disease: A low ferritin level with normal iron studies can be seen in chronic diseases such as chronic infections, inflammatory conditions (e.g., rheumatoid arthritis), or malignancies. Ferritin can be low due to the body's prioritization of iron utilization in these conditions, despite adequate iron stores.

• Other Likely Diagnoses

  • Hypothyroidism: Some patients with hypothyroidism may have low ferritin levels, possibly due to decreased iron absorption or other metabolic changes associated with the condition.
  • Malabsorption: Conditions leading to malabsorption, such as celiac disease or gastric bypass surgery, can result in low ferritin due to impaired iron absorption, even if other iron parameters are currently within normal limits.
  • Chronic Kidney Disease (CKD): CKD can lead to disturbances in iron metabolism, potentially resulting in low ferritin levels, although this might be more commonly associated with changes in other iron parameters as well.

• Do Not Miss Diagnoses

  • Hemochromatosis with Iron Depletion: Although less common, it's crucial not to miss hemochromatosis, especially if the patient has been donating blood frequently or has had recent iron loss, which could temporarily normalize iron studies despite an underlying genetic predisposition to iron overload.
  • Thalassemia Major or Intermedia: These conditions can sometimes present with low ferritin due to ineffective erythropoiesis and increased iron turnover, despite the potential for iron overload in thalassemia major.

• Rare Diagnoses

  • Atransferrinemia: A rare genetic disorder characterized by the absence of transferrin, leading to low ferritin and potentially abnormal iron studies, although this condition is extremely rare and usually presents with more pronounced abnormalities in iron metabolism.
  • Aceruloplasminemia: Another rare genetic disorder affecting iron metabolism, characterized by the absence of ceruloplasmin, which can lead to iron accumulation in tissues but might present with low ferritin levels in some cases.

Each of these diagnoses has a different set of implications for patient management and further diagnostic workup. It's essential to consider the clinical context, including symptoms, medical history, and other laboratory findings, to narrow down the differential diagnosis and guide appropriate testing and treatment.