Can LDH, Bilirubin, and Haptoglobin Tests Reveal the Cause of Anemia?

Question: Would additional labs like LDH, bilirubin, and haptoglobin help determine the degree of hemolysis versus other contributing factors to the anemia?

Expert Answer: During the investigation of suspected hemolytic anemia, we would expect an elevated LDH and total bilirubin, but a low haptoglobin. It’s important to keep in mind, however, that these lab values can be influenced by other processes occurring in the body. For example, haptoglobin can be falsely increased in the presence of inflammation and infection as it is an acute phase reactant. Also, LDH is a non-specific marker of tissue damage which can cause it to be falsely elevated.

Of course, a CBC would probably have already been done, showing that the anemia is normocytic and normochromic. I have found red cell morphologies in the peripheral blood smear to be helpful. Sometimes, we may see schistocytes and basophilic stippling that give clues. Other laboratory tests that could be performed include a reticulocyte count, which we would expect to see elevated if the bone marrow is appropriately responding to the anemia.

And I would further consider a DAT, which may include IgG and C3 in the workup of determining an immune cause, which may include autoimmune, drug induced, or alloimmune hemolytic anemias.

Questions for your provider:

> Are there additional lab tests—like LDH, bilirubin, or haptoglobin—that can help determine if my anemia is caused by red blood cell destruction?

> Could a blood smear or reticulocyte count give more information about what's causing my anemia?