Differential Diagnosis for High FDP (>20), Low Plasma Fibrinogen, and D Dimer 4000

• Single Most Likely Diagnosis

  • Disseminated Intravascular Coagulation (DIC): This condition is characterized by both widespread clotting and bleeding in the vascular system, leading to the consumption of clotting factors and fibrinogen, thus explaining the low plasma fibrinogen levels. The high FDP (fibrin degradation products) and significantly elevated D dimer levels are indicative of ongoing fibrinolysis and thrombus formation, respectively, which are hallmarks of DIC.

• Other Likely Diagnoses

  • Severe Sepsis or Septic Shock: In severe infections, the inflammatory response can trigger coagulation pathways, leading to increased levels of FDP and D dimer due to the formation and breakdown of fibrin clots. The consumption of clotting factors, including fibrinogen, can result in its decreased levels.
  • Major Trauma: Significant trauma can initiate a coagulopathic state similar to DIC, with the release of tissue factor and subsequent activation of the coagulation cascade, leading to elevated FDP and D dimer levels and decreased fibrinogen.

• Do Not Miss Diagnoses

  • Pulmonary Embolism (PE): Although less likely to cause such a significant elevation in FDP and decrease in fibrinogen as seen in DIC, a large PE could potentially lead to these lab findings, especially if there is associated right heart strain or failure. Missing this diagnosis could be fatal.
  • Aortic Dissection: This condition involves a tear in the aorta's inner layer, which can lead to activation of the coagulation system and potentially result in elevated D dimer and FDP levels. The clinical presentation and these lab findings together should prompt consideration of this diagnosis due to its high mortality rate if untreated.

• Rare Diagnoses

  • Thrombotic Thrombocytopenic Purpura (TTP): A rare disorder characterized by the formation of blood clots in small blood vessels throughout the body, which could potentially lead to elevated levels of FDP and D dimer. However, the primary features of TTP are thrombocytopenia, microangiopathic hemolytic anemia, renal failure, neurological symptoms, and fever, which would distinguish it from the primary coagulopathy suggested by the lab values provided.
  • Hemolytic Uremic Syndrome (HUS): Similar to TTP, HUS involves microvascular thrombi formation but is more commonly associated with renal failure and microangiopathic hemolytic anemia. The coagulation profile might show some similarities, but the clinical context and other laboratory findings would be more indicative of HUS.