Final answer:
In hemolytic anemia due to warm or cold agglutinin disease, LDH levels increase, bilirubin levels rise due to hemoglobin breakdown, and haptoglobin decreases as it binds the released hemoglobin. The Coombs' test is used to detect the presence of antibodies on red blood cells.
Step-by-step explanation:
During hemolysis, which is the destruction (lysis) of erythrocytes and release of hemoglobin into circulation, several laboratory changes occur. Lactate dehydrogenase (LDH) levels increase due to the release of cellular contents from lysed red blood cells. Bilirubin also increases as a product of hemoglobin breakdown. Haptoglobin, however, decreases because it binds free hemoglobin released during hemolysis but is consumed in the process.
In conditions like warm or cold agglutinin disease, which are types of autoimmune hemolytic anemias, the Coombs' test (direct antiglobulin test) is employed to determine the presence of antibodies attached to red blood cells. A positive Coombs' test indicates that antibodies are bound to the erythrocytes, activating the complement system and leading to further hemolysis and anemia.