Thread by @AndreMansoor

1/11
A young woman presents with bleeding from her nose and gums and the following skin rash.

2/11
Petechiae are pinpoint hemorrhages <2 mm in size, purpura are 2 mm to 1 cm, and ecchymoses are >1 cm. Our patient has all three. These lesions are the result of extravasation of blood from the vasculature into skin/mucosa and do not blanch, as shown in this video:

3/11
A platelet disorder could explain these symptoms and physical findings.

But is the platelet issue qualitative (platelets are normal in number but abnormal in function) or quantitative (platelets are normal in function, but abnormal in number)?

4/11
A CBC can sort us out.

5/11
Now that we know we are dealing with thrombocytopenia, our next question is... are platelets not being produced appropriately, or are they being destroyed?

6/11
Well there's a test for that too.

Immature platelets = newly released platelets.

The immature platelet fraction is like an RBC reticulocyte count. If low/normal, there is decreased platelet production; if elevated, there is increased platelet destruction.

7/11
The elevated immature platelet fraction tells us we are dealing with a process causing platelet destruction.

The bone marrow is responding appropriately and cranking out platelets, it just can't keep up.

8/11
So what's our diagnosis?

9/11
The degree of thrombocytopenia (1!) narrows our differential to TMA and HIT. The absence of concomitant hemolytic anemia points us to the right diagnosis:

10/11
ITP is an acquired d/o characterized by autoantibody-mediated platelet destruction. It can be primary or secondary (eg, SLE). In adults, it's often a chronic condition. In our case, @Bloodman recommended steroids + IVIG and our patient's platelet count has recovered nicely.

11/11
If you liked how we approached platelet disorders to arrive at the diagnosis in this case, you might like #FrameworksForInternalMedicine

amazon.com/Frameworks-Int…