Which of the following is NOT a characteristic of hemolytic uremic syndrome (HUS)?

Hemolytic uremic syndrome (HUS) is characterized by a triad of symptoms: hemolytic anemia, acute renal failure, and thrombocytopenia. Among the options presented, reticulocytopenia is not characteristic of HUS.

In HUS, because of the destruction of red blood cells, the bone marrow's response is to increase the production of new red blood cells, which is indicated by an increased number of reticulocytes. Thus, an increase in reticulocyte count is typically seen as the body attempts to compensate for the hemolytic anemia.

On the other hand, hemorrhage can occur in various forms during HUS due to thrombocytopenia, and hemoglobinuria may be present as hemolysis leads to free hemoglobin spilling into the urine. Thrombocytopenia is a defining feature of the syndrome. Therefore, the absence of reticulocytopenia aligns it with the characteristics of HUS, as the condition typically presents with an increased reticulocyte count due to compensatory mechanisms in response to hemolysis.