Platelet disorders: Pathology review

At the family medicine center, a mother came in with her 5 year old child, Alana.

Several days ago, Alana developed bloody diarrhea after eating undercooked ground beef and her mother noticed her face was pale and she only urinated once in the past 12 hours.

Next to her, there’s a 30 year old person named Danika, who came in complaining of increased bruising for the past several months.

She has no other symptoms and physical examination shows multiple ecchymoses on the extremities.

Both Alana and Danika are suffering from a hemostasis disorder.

Hemostasis disorders, also known as bleeding disorders, can be broadly divided into three groups.

The first includes problems with primary hemostasis, which is when there’s a problem forming the initial platelet plug, and so, they’re referred to as platelet disorders.

Now, the second group includes problems with secondary hemostasis, which is making a strong fibrin clot through activation of the intrinsic, extrinsic and common coagulation pathways, and are also known as coagulation disorders.

And the last group includes disorders that affect both primary and secondary hemostasis and are known as mixed platelet and coagulation disorders.

For this video, let’s focus on the platelet disorders.

These can be further subdivided into two categories. In the first category, there’s thrombocytopenia, which is defined as a platelet count below 150,000 per microliter, with the normal range being between 150,000 and 450,000.

Thrombocytopenia can be caused by increased platelet destruction, which can be immune-mediated, like in heparin induced thrombocytopenia, or HIT, and immune thrombocytopenic purpura, or ITP.

Other cases can be non-immune mediated, like thrombotic thrombocytopenic purpura, or TTP, and hemolytic-uremic syndrome, or HUS.