ITP vs TTP

Introduction

Immune Thrombocytopenic Purpura (ITP) and Thrombotic Thrombocytopenic Purpura (TTP) are both hematologic conditions characterized by thrombocytopenia (low platelets), but they differ dramatically in cause, severity, and treatment.

ITP is an autoimmune disorder where antibodies mistakenly target platelets for destruction in the spleen and other parts of the reticuloendothelial system¹. This leads to isolated thrombocytopenia and a bleeding tendency, but typically without other blood abnormalities.

In contrast, TTP is a thrombotic microangiopathy caused by a severe deficiency of the enzyme ADAMTS13, which normally cleaves large von Willebrand factor (vWF) multimers². Without enough ADAMTS13, platelet-rich microthrombi form throughout the small vessels, causing widespread organ ischemia, hemolytic anemia, and profound thrombocytopenia. TTP is a medical emergency requiring urgent plasma exchange to prevent death.

Rapid differentiation between these two conditions is critical, as delayed treatment of TTP can be fatal, while ITP often follows a more benign course.

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Comparison Table: ITP vs TTP

Feature	ITP	TTP
Pathophysiology	Autoimmune destruction of platelets¹	Deficiency of ADAMTS13 enzyme → microvascular thrombosis²
Symptoms	Petechiae, purpura, mucosal bleeding	Fever, neurologic changes, renal injury, purpura
Common Patient Complaints	Easy bruising, bleeding gums, heavy periods	Confusion, weakness, chest pain, dark urine
Platelet Count	Often <30,000/µL¹	Often <20,000/µL²
Hemoglobin	Normal or mildly low¹	Decreased (due to hemolysis)²
Peripheral Smear	Few platelets, otherwise normal	Schistocytes (helmet cells) seen²
Other Expected Labs	Normal coagulation (PT/PTT) Normal creatinine	Elevated LDH Elevated indirect bilirubin Decreased haptoglobin Elevated creatinine³
Key Distinction	Isolated thrombocytopenia	Thrombocytopenia + Microangiopathic Hemolytic Anemia (MAHA)
Mnemonic	None standardized	“FAT RN” → Fever, Anemia, Thrombocytopenia, Renal dysfunction, Neurologic signs
Treatment	Steroids, IVIG, platelet transfusion if bleeding	Plasma exchange (PLEX) urgently + steroids

Expected Lab Abnormalities

Test	ITP	TTP
Platelets	Low (<30,000)	Very low (<20,000)
Hemoglobin	Normal or mildly low	Low (due to hemolysis)
Peripheral Smear	Normal or large platelets	Schistocytes present
Coagulation Panel (PT/PTT)	Normal	Normal
Creatinine	Normal	Elevated
LDH	Normal	Elevated
Bilirubin (indirect)	Normal	Elevated
Haptoglobin	Normal	Decreased

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Treatment Details

ITP

Pediatric

• Most pediatric ITP cases are acute and self-limited, often following a viral illness.
• Observation alone is recommended for children with no or only mild bleeding, regardless of platelet count¹.
• Treat if: Significant bleeding or high-risk features.
  • IVIG: 1 g/kg IV daily for 1–2 days
  • Steroids: Prednisone 1–2 mg/kg/day orally for 5–7 days (short course)

Adults

• Adult ITP is often chronic and less likely to resolve spontaneously.
• Treat if: Platelet count <30,000/µL or any active bleeding².
  • Prednisone: 1 mg/kg/day orally for 1–2 weeks, then taper
  • IVIG: 1 g/kg IV daily for 1–2 days if rapid platelet increase needed

Platelet transfusions are reserved for life-threatening bleeding in both adults and children.

TTP

Pediatric

• Pediatric TTP treatment is similar to adults:
  • Plasma exchange (PLEX) daily until platelet count and LDH normalize¹.
  • High-dose corticosteroids (e.g., methylprednisolone 1–2 mg/kg/day IV) as adjunct therapy¹.
  • Rituximab can be added for refractory or relapsed cases.
• Hereditary (congenital) TTP:
  • Suspected in very young children or familial cases.
  • Treat with plasma infusions (not plasma exchange) to replace deficient ADAMTS13³.

Adults

• Plasma exchange (PLEX) daily until clinical and laboratory recovery².
• Methylprednisolone 1 mg/kg/day IV as adjunct therapy².
• Rituximab or caplacizumab in refractory or relapsed cases³.

Platelet transfusions are contraindicated in TTP unless there is active life-threatening hemorrhage.

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References

1. Neunert C, Terrell DR, Arnold DM, et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Adv. 2019;3(23):3829–3866. doi:10.1182/bloodadvances.2019000966
2. George JN. Thrombotic thrombocytopenic purpura. N Engl J Med. 2006;354(18):1927–1935. doi:10.1056/NEJMra052618
3. Joly BS, Coppo P, Veyradier A. Thrombotic thrombocytopenic purpura. Blood. 2017;129(21):2836–2846. doi:10.1182/blood-2016-10-709857

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Further Reading

The Young Child With Lower Gastrointestinal Bleeding Or Intussusception

An Evidence-Based Approach To The Management Of Hematuria In Children In The Emergency Department

Altered Level of Consciousness: Evidence-Based Management in the Emergency Department

Pediatric Stroke: Diagnosis and Management in the Emergency Department

Managing the HIV-Infected Adult Patient in the Emergency Department

Anemia In The Emergency Department: Evaluation And Treatment

Tick-Borne Illnesses: Identification and Management in the Emergency Department

Managing Postpartum Complications in the Emergency Department

Last Updated on May 1, 2025