Elevated Lactate dehydrogenase (LDH)
Elevated indirect Bili
Reduced haptoglobin
Why increased LDH?
Lactate dehydrogenase (LDH or LD) is an enzyme found in nearly all living cells (animals, plants, and prokaryotes). LDH catalyzes the conversion of lactate to pyruvic acid and back, as it converts NAD+ to NADH and back. A dehydrogenase is an enzyme that transfers a hydride from one molecule to another.
In Hemolysis, LDH is high in blood simply because many cells inside the intravascular space are being destroyed (hemolysis) and their insides spewing into the intravascular space together with the LDH inside them. So you will normally have elevated LDH beyond what is normal for the usual recycling of RBCs and other cells in blood.
Why elevated indirect or unconjugated bilirubin?
Well, hemolysis is happening at a great scale than the liver can handle to conjugate the bilirubin.
Why is haptoglobin reduced?
Haptoglobin (abbreviated as Hp) is the protein that in humans is encoded by the HP gene. In blood plasma, haptoglobin binds free hemoglobin (Hb) released from erythrocytes with high affinity and thereby inhibits its oxidative activity. The haptoglobin-hemoglobin complex will then be removed by the reticuloendothelial system (mostly the spleen).
In clinical settings, the haptoglobin assay is used to screen for and monitor intravascular hemolytic anemia. In intravascular hemolysis, free hemoglobin will be released into circulation and hence haptoglobin will bind the hemoglobin. This causes a decline in haptoglobin levels. Conversely, in extravascular hemolysis the reticuloendothelial system, especially splenic monocytes, phagocytose the erythrocytes and hemoglobin is relatively not released into circulation; however, excess hemolysis can release some hemoglobin causing haptoglobin levels to be decreased. Therefore, haptoglobin is not a reliable way to differentiate between intravascular and extravascular hemolysis.