Differential Diagnosis for Acquired Antithrombin III Deficiency

• Single Most Likely Diagnosis
  • Nephrotic syndrome: This condition is characterized by severe proteinuria, leading to the loss of antithrombin III, a protein that helps regulate blood clotting. The loss of antithrombin III increases the risk of thrombosis.
• Other Likely Diagnoses
  • Liver disease: The liver produces antithrombin III, and liver dysfunction can lead to decreased production of this protein, resulting in deficiency.
  • Disseminated intravascular coagulation (DIC): This condition involves both widespread clotting and bleeding in the vascular system, consuming antithrombin III and leading to its deficiency.
  • Sepsis: Severe infections can lead to the consumption of antithrombin III as part of the inflammatory response, resulting in deficiency.
• Do Not Miss Diagnoses
  • Heparin-induced thrombocytopenia with thrombosis (HITT): Although heparin is used to treat thrombosis, in some cases, it can induce an immune response that leads to the formation of antibodies against platelet factor 4, potentially consuming antithrombin III and leading to a paradoxical thrombotic state.
  • Malignancy: Certain cancers can increase the risk of thrombosis and consume antithrombin III, either through direct production of pro-coagulant factors or through tumor effects on the coagulation system.
• Rare Diagnoses
  • L-asparaginase therapy: Used in the treatment of certain leukemias, L-asparaginase can lead to decreased production of antithrombin III, among other coagulation factors.
  • Congenital conditions becoming apparent in adulthood: While less common, some individuals with congenital antithrombin III deficiency may not be diagnosed until adulthood, especially if they have a mild deficiency or have not experienced significant thrombotic events earlier in life.