PATH - Platelet Disorders

Question 1

Bernard-Soulier syndrome

Answer 1

-/DEC Platelet Count (PC)
INC BT

Defect in platelet plug formation

Large platelets

DEC *GpIb–>defect in *platelet-to-vWF adhesion.

Question 2

Glanzmann thrombasthenia

Answer 2

INC BT

Defect in platelet plug formation

DEC *GpIIb/IIIa–>defect in *platelet-to-platelet aggregation.

Labs: blood smear shows *no platelet clumping

Question 3

Hemolytic-uremic syndrome

HUS

Answer 3

DEC PC
INC BT

Typical HUS is seen in children, accompanied by diarrhea and commonly
caused by Shiga toxin-producing E coli (*STEC) (eg, O157:H7).

thrombocytopenia, microangiopathic hemolytic anemia, and
acute renal failure.

TX: plasmapheresis, steroids

Question 4

Immune thrombocytopenia

Answer 4

DEC PC
INC BT

Anti-GpIIb/IIIa antibodies–>splenic macrophage consumption of
platelet-antibody complex

Commonly due to viral illness

Labs: INC megakaryocytes on bone marrow biopsy.

Treatment: steroids, IVIG, splenectomy (for refractory ITP).

Question 5

Thrombotic thrombocytopenia

purpura (TTP)

Answer 5

DEC PC
INC BT

SX: pentad of neurologic and renal symptoms, fever, thrombocytopenia,
and microangiopathic hemolytic anemia

Inhibition or deficiency of *ADAMTS 13–>DEC degradation of vWF multimers.

INC large vWF multimers–>INC platelet adhesion–>INC platelet aggregation and thrombosis.

Labs: schistocytes,  INC LDH

Treatment: plasmapheresis, steroids

Question 6

von Willebrand disease

Answer 6

INC PT
-/INC PTT

Autosomal dominant

Intrinsic pathway coagulation defect: DEC vWF–>INC PTT

Defect in platelet plug formation: DEC vWF–>defect in *platelet-to-vWF adhesion.

Mild but most common
inherited bleeding disorder

TX: desmopressin, which releases vWF stored in endothelium

Question 7

Disseminated intravascular

coagulation (DIC)

Answer 7

DEC PC
INC BT
INC PT
INC PTT

Widespread activation of clotting–>deficiency in clotting factors–>*bleeding state.

Causes: Sepsis (gram ⊝), Trauma, Obstetric
complications, acute Pancreatitis, Malignancy, Nephrotic syndrome,
Transfusion (STOP Making New Thrombi).

Labs: schistocytes
INC fibrin degradation
products (d-dimers)
DEC fibrinogen
DEC factors V and VIII.