Which of the following tests can indicate the presence of hemolytic anemia?

A positive Coombs test is indicative of hemolytic anemia because it demonstrates the presence of antibodies that are targeting the body's own red blood cells (RBCs). In hemolytic anemia, the immune system mistakenly identifies healthy RBCs as foreign and produces antibodies against them. The Coombs test can be either direct, detecting antibodies bound to warm or cold reactive RBCs, or indirect, detecting free antibodies in the serum. When this test is positive, it confirms the immune-mediated destruction of red blood cells, which is characteristic of hemolytic anemia.

The other options do not specifically signal hemolytic anemia. A high platelet count is often associated with various conditions but is not specific to hemolytic anemia. High hemoglobin levels can occur in many conditions and do not indicate hemolysis. Increased cholesterol levels are more related to lipid metabolism and do not correlate with hemolytic processes in the blood. Thus, the positive Coombs test stands out as the test directly linking to the pathophysiology of hemolytic anemia.