Thrombotic thrombocytopenic purpura
Thrombotic thrombocytopenic purpura | |
---|---|
Other names | Moschcowitz syndrome, immunosuppressants[1] |
Prognosis | < 20% risk of death[1] |
Frequency | 1 in 100,000 people[3] |
Thrombotic thrombocytopenic purpura (TTP) is a
In about half of cases a trigger is identified, while in the remainder the cause remains unknown.
With
About 1 per 100,000 people are affected.[3] Onset is typically in adulthood and women are more often affected.[3] About 10% of cases begin in childhood.[3] The condition was first described by Eli Moschcowitz in 1924.[3] The underlying mechanism was determined in the 1980s and 1990s.[3]
Signs and symptoms
The signs and symptoms of TTP may at first be subtle and nonspecific. Many people experience an
As TTP progresses, blood clots form within small blood vessels (microvasculature), and platelets (clotting cells) are consumed. As a result, bruising, and rarely bleeding can occur. The bruising often takes the form of purpura, while the most common site of bleeding, if it occurs, is from the nose or gums. Larger bruises (
- Fever
- Changes in mental status
- Thrombocytopenia
- Reduced kidney function
- Hemolytic anemia (microangiopathic hemolytic anemia).[7]
Causes
TTP, as with other
Autoimmune
In 1998, the majority of cases were shown to be caused by the inhibition of the enzyme
ADAMTS13 is a
Genetic
TTP may also be
Secondary
Secondary TTP is diagnosed when the person's history mentions one of the known features associated with TTP. It comprises about 40% of all cases of TTP. Predisposing factors are:[12]
- Cancer
- Bone marrow transplantation
- Pregnancy
- Medication use:
- Antiviral drugs (acyclovir)
- Certain chemotherapy medications such as gemcitabine and mitomycin C
- Quinine
- Oxymorphone
- Quetiapine
- Bevacizumab
- Sunitinib
- Platelet aggregation inhibitors (ticlopidine, clopidogrel, and prasugrel)
- Immunosuppressants (mitomycin, tacrolimus/FK506, interferon-α)
- Hormone altering drugs (estrogens, contraceptives, hormone replacement therapy)[24]
- Antiviral drugs (
- HIV-1infection
The mechanism of secondary TTP is poorly understood, as ADAMTS13 activity is generally not as depressed as in idiopathic TTP, and inhibitors cannot be detected. Probable etiology may involve, at least in some cases, endothelial damage,[25] although the formation of thrombi resulting in vessel occlusion may not be essential in the pathogenesis of secondary TTP.[26] These factors may also be considered a form of secondary aHUS; people presenting with these features are, therefore, potential candidates for anticomplement therapy.
Pathophysiology
The underlying mechanism typically involves autoantibody-mediated inhibition of the enzyme
Recovery
Depression is common in those recovering from TTP; 59% of recovered TTP patients screened positive for depression within 11 years after recovery.[28]
Diagnosis
Differential diagnosis
TTP is a form of
Unlike HUS and aHUS,
Treatment
Due to the high mortality of untreated TTP, a
Caplacizumab is an alternative option in treating TTP as it has been shown that it induces a faster disease resolution compared with those people who were on placebo.[38] However, the use of caplacizumab was associated with increase bleeding tendencies in some studied subjects.[39]
People with refractory or relapsing TTP may receive additional
Children with Upshaw-Schulman syndrome receive prophylactic plasma every two to three weeks; this maintains adequate levels of functioning ADAMTS13. Some tolerate longer intervals between plasma infusions. Additional plasma infusions may be necessary for triggering events, such as surgery; alternatively, the platelet count may be monitored closely around these events with plasma being administered if the count drops.[40]
Measurements of blood levels of lactate dehydrogenase, platelets, and schistocytes are used to monitor disease progression or remission.[13][41] ADAMTS13 activity and inhibitor levels may be measured during follow-up, but in those without symptoms the use of rituximab is not recommended.[36]
Apadamtase alfa (Adzynma) was approved for medical use in the United States in November 2023.[42][43]
Prognosis
The mortality rate is around 95% for untreated cases, but the prognosis is reasonably favorable (80–90% survival) for people with idiopathic TTP diagnosed and treated early with plasmapheresis.[44]
Epidemiology
The incidence of TTP is about 4–5 cases per million people per year.
History
TTP was initially described by
While a response to blood transfusion had been noted before, a 1978 report and subsequent studies showed blood plasma was highly effective in improving the disease process.[52] In 1991, plasma exchange was reported to provide better response rates compared to plasma infusion.[53] In 1982, the disease had been linked with abnormally large von Willebrand factor multimers. The identification of a deficient protease in people with TTP was made in 1998. The location of ADAMTS13 within the human genome was identified in 2001.[52]
References
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- ^ "MAHA, TTP, HUS, DIC... Oh My! Understanding Microangiopathic Hemolytic Anemias". Tampa Emergency Medicine Blog. University of South Florida. 2023-04-26. Retrieved 2023-08-23.
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In contrast to TTP, HUS is not caused by a deficiency of ADAMTS13.
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Complement dysregulation leads to atypical hemolytic uremic syndrome (aHUS), while ADAMTS13 deficiency causes thrombotic thrombocytopenic purpura.
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- ^ "FDA Approves First Treatment for Patients with Rare Inherited Blood Clotting Disorder". U.S. Food and Drug Administration (Press release). 9 November 2023. Retrieved 30 November 2023.
- ^ "Takeda's Adzynma (ADAMTS13, recombinant-krhn) Approved by U.S. FDA as the First and Only Recombinant ADAMTS13 Enzyme Replacement Therapy for the Treatment of Congenital Thrombotic Thrombocytopenic Purpura (cTTP)" (Press release). Takeda Pharmaceuticals. 9 November 2023. Retrieved 30 November 2023 – via Business Wire.
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