Peripheral smear call thread #2: Hemolysis #hemepath
2/If the bone marrow is responding appropriately to hemolysis, there should be a reticulocyte response (& increased polychromasia on the smear). Lab abnormalities associated with hemolysis include increased LDH, increased unconjugated bili, and decreased haptoglobin.
3/Side note: these “hemolysis labs” are not totally specific. LDH is increased in other conditions where cell death / turnover is increased, including liver disease, malignancy, and MI.
4/Haptoglobin binds free hemoglobin and decreases in intravascular hemolysis – but haptoglobin is made in the liver, so it can be decreased in patients with severe liver disease. Haptoglobin levels are normally low in neonates – it takes a few months to reach adult levels.
5/Don’t forget that LDH can be markedly increased (and haptoglobin decreased) in megaloblastic anemia due to ineffective erythropoiesis and increased cell turnover in the bone marrow. 
6/Haptoglobin is also an acute phase reactant, so baseline haptoglobin levels may be increased in patients with inflammatory conditions.
7/Spherocytes form when there is loss of cell membrane without loss of cytosol. They are smaller than normal RBCs and lack central pallor (black arrows).
8/Main DDx for increased spherocytes is autoimmune hemolysis vs hereditary spherocytosis, but they can also be seen in HDN, delayed transfusion reaction, spider bite, and other forms of hemolysis.
9/Potential pitfall when calling spherocytes – don’t look too close to the edge of the smear, where there may be an artifactual loss of central pallor. Look for retained central pallor in at least some of the RBCs in your field of view.
10/Schistocytes are RBC fragments that have flat or sharp edges, are smaller than intact RBCs, and lack central pallor. Seen in mechanical hemolysis (mechanical heart valve, vascular malformation), and MAHA (TTP, HUS, DIC, HELLP).
11/Schistocytes can also be seen in hypertensive emergencies – don’t forget to check the vital signs!
12/Oxidative hemolysis in a patient with G6PD deficiency. RBCs are “irregularly contracted” (it looks like the hemoglobin pooled off to one side of the cell), with scattered blister cells and bite cells.
13/For anyone looking for a good reference on blood cell morphology, I really like this one. It was required reading in my hemepath fellowship (several editions ago…). The CAP Clinical Microscopy Glossary and ASH Image Bank are also great resources.
