Which features define the classic pentad of thrombotic thrombocytopenic purpura?

Which features define the classic pentad of thrombotic thrombocytopenic purpura?

• A. Thrombocytopenia, microangiopathic hemolytic anemia, kidney failure, neurologic sxs, fever
• B. Anemia, hyperkalemia, jaundice, splenomegaly, rash
• C. Thrombocytosis, microcytosis, high platelets, high BP, diabetes
• D. MAHA, retinopathy, cholestasis, leukopenia

Answer: (A)

The main concept here is a classic thrombotic microangiopathy caused by severe deficiency of the enzyme ADAMTS13, which leads to the formation of platelet-rich microthrombi in small vessels. This results in two hallmark lab findings: low platelets from platelet consumption (thrombocytopenia) and microangiopathic hemolytic anemia, where red cells are sheared as they pass through damaged microvasculature (evidenced by schistocytes, elevated LDH, and low haptoglobin). The full classic pentad includes five features: thrombocytopenia, microangiopathic hemolytic anemia, kidney dysfunction, neurologic symptoms, and fever. The presence of thrombocytopenia and MAHA explains the anemia and bruising/bleeding tendency, while kidney involvement reflects microthrombi in renal vessels; neurologic symptoms arise from cerebral microvascular ischemia; fever is a common accompanying sign. So option that lists MAHA and thrombocytopenia along with kidney failure, neurologic symptoms, and fever aligns exactly with the classic pentad. Other options mix in findings that aren’t characteristic of the pentad (for example, high platelets rather than low, or findings like splenomegaly or leukopenia) and don’t represent the same pattern of microangiopathic processes seen in TTP.

The main concept here is a classic thrombotic microangiopathy caused by severe deficiency of the enzyme ADAMTS13, which leads to the formation of platelet-rich microthrombi in small vessels. This results in two hallmark lab findings: low platelets from platelet consumption (thrombocytopenia) and microangiopathic hemolytic anemia, where red cells are sheared as they pass through damaged microvasculature (evidenced by schistocytes, elevated LDH, and low haptoglobin).

The full classic pentad includes five features: thrombocytopenia, microangiopathic hemolytic anemia, kidney dysfunction, neurologic symptoms, and fever. The presence of thrombocytopenia and MAHA explains the anemia and bruising/bleeding tendency, while kidney involvement reflects microthrombi in renal vessels; neurologic symptoms arise from cerebral microvascular ischemia; fever is a common accompanying sign.

So option that lists MAHA and thrombocytopenia along with kidney failure, neurologic symptoms, and fever aligns exactly with the classic pentad. Other options mix in findings that aren’t characteristic of the pentad (for example, high platelets rather than low, or findings like splenomegaly or leukopenia) and don’t represent the same pattern of microangiopathic processes seen in TTP.