QUESTIONS

1. How is splenectomy supposed to help recurrent or chronic ITP or AIHA?
    
2. For every platelet you see under oil, approximately how many are circulating?
    
3. Is a larger platelet likely to be an older platelet or a younger platelet?
    
4. What is the point in quantitating platelet fragments?
    
5. What is the best anticoagulant for platelets?
   
   
   
   
    

ANSWERS

1. The spleen is the organ removing the opsonized cells.  Remove the spleen & the cell stay.  The problem is that sometimes the liver is the organ removing the opsonized cells & you sure can’t remove the liver.  You CAN do radiolabelling of platelets before removing anything & see which organ is doing the cell removal.  Note also, before removing the spleen, make sure the marrow is active as you don’t want to remove an important site of hematopoesis.
   
   
   
   
    
2. The guideline is that every platelet you see corresponds to 20,000 circulating platelets.
   
   
   
   
    
3. Large platelets tend to be younger which brings us to the concept of mean platelet volume.  If on a smear you see only small platelets, there may be reduced megakaryocytes in the marrow (a 57% correlation).  If on a smear you see lots of large platelets, the marrow is presumed to be actively producing platelets (96% correlation to increased numbers of megakaryocytes in the marrow.)
   
   
   
   
    
4. With the platelet factor 3 test having some 28% false positives, it would be good to have a better test to diagnose ITP.  Any platelet less than 2.1 femtoliters is considered a fragment.  Normally there are 5% fragments.  In ITP there are significantly more fragments.  Watch for a new diagnostic method using this idea in the near future.
   
   
   
   
    
5. Citrate seems to preserve size & shape the best.