Thrombocytopenia is due to three main problems: DECREASED PRODUCTION (bone marrow), INCREASED DESTRUCTION, SPLENIC SEQUESTRATION:

Decreased Production:

• Aplastic anemia
• Hematologic malignancies
• Myelodysplastic syndrome
• Chronic alcoholism
• Infiltrative process (myelofibrosis, infection, etc.)

Increased Production:

• Immune disorders
  • ITP
  • Drug induced (heparin, sulfonamides, thiazides, etc.)
• DIC
• TTP
• HUS
• Sepsis
• AIDs/Viral infection
• Liver Failure

Splenic Sequestration

Causes of MAHA:

• DIC
• TTP/HUS
• Malignant hypertension
• Mechanical valves
• HELLP/Pre-eclampsia
• Scleroderma renal crisis

TTP Pentad: ONLY PRESENT IN 1/3 OF PATIENTS

• Thrombocytopenia
• MAHA (schistocytes on smear)
• Acute renal insufficiency
• Fevers
• Encephalopathy

*Only need thrombocytopenia and MAHA to diagnose

Triad more common:

• Elevated LDH (tissue hypoxia/injury)
• Schistocytes
• Thrombocytopenia

ADMTS 13 Testing

• Protease that cleaves vWF multimers; deficiency leads to increase vWF leading to platelet aggregation (thrombocytopenia) and disruption/breaking of RBCs (MAHA)

Level of activity:

• >50% ~ unlikely TTP
• <10% ~ suggests TTP

*presence of ADAMTS 13 inhibitor suggests acquired TTP; negative suggests hereditary.

Treatment:

• Plasma exchange
• If unavailable – infuse FFP
• Other options: steroids, splenectomy, rituximab, vincristine

* AVOID PLATELET TRANSFUSION AT ALL COSTS!

HUS:

• Usually occurs in children ~ associated with E. coli 0157:H7
• Most patients don’t have wide-spread symptoms; besides heme changes, renal involvement is the rule
• In adults => progressive renal failure => ESRD
• Supportive treatment in children, assume TTP in adults