Piastrinopenie

Name: Piastrinopenie
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Aggiornato il 19/03/2026

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Appunti di ematologia su: Piastrinopenia. Trombocitopenia, numero delle piastrine, trombocitopoiesi, megacariociti, trombopoietina, danno vascolare, ruole delle piastrine nelle emorragie e …

Esame Ematologia

Facoltà Medicina e chirurgia

Dal corso del Prof. Liso Arcangelo

Università Università degli Studi di Foggia

A.A. 2011-2012

62 pagine

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Estratto del documento

Thrombocytopenia

Normal platelet production and survival

Normal platelet count in adults ranges from 150,000 - 450,000 / μL.

Thrombocytopenic bleeding

Risk of thrombocytopenic hemorrhage in AML is significantly high with platelet counts below critical levels.

Surgical bleeding when platelet count is less than 50,000/microL
Spontaneous bleeding if the platelet count is less than 10,000-20,000 /microL

Management

General

Avoid trauma.
Stop use of hard tooth brushes, dental floss, or metal razors.
Avoid use of non-steroidal anti-inflammatory agents (NSAIDs).
Avoid intramuscular injections.
Stop drugs known to interfere with platelet function or induce thrombocytopenia.
Minimize rectal examination, suppositories, and enemas.
Minimize phlebotomy. Apply pressure to venipuncture sites for at least 10 minutes.

Platelet transfusion

Transfused platelets survive on average 5 days.
Platelets should be transfused within 10 minutes.
Transfuse platelets using a filter to reduce leukocytes.
Platelet count may be done after 45-60 minutes to assess efficacy.
Platelets for transfusion stored at room temperature (20-24°C), in a gently agitated state.
Platelet transfusion does not require cross-matching. Group-compatibility of donor platelets/plasma may be ideal, but do not withhold emergency platelet transfusion on that account.
Unwarranted platelet transfusion generates alloimmunisation, reducing efficacy of future transfusions.

Critical bleeding

The most critical bleeding are the:

Intracranial
Intraocular (retinal)
Intraabdominal

Though such bleeding is infrequent, it is mandatory that all patients are assessed for such potential risks.

Risk of bleeding

Factors include:

Platelet count
Cause of thrombocytopenia
Comorbid disease
Drugs

5 Mechanisms of Thrombocytopenia

Pseudothrombocytopenia
Decreased platelet production
Increased platelet destruction

Differential diagnosis

Conditions such as ITP and DIC should be considered.

ITP

Immune thrombocytopenia presents unique diagnostic challenges.

DIC

Disseminated intravascular coagulation is characterized by its distinct pathology.

Pregnancy

Pregnancy-related changes can significantly affect platelet count and function.

Platelets: Physiology

Thrombocytopoiesis is a complex process involving several stages:

Pluripotent stem cell
Mixed progenitor cell
Committed progenitor cell
Recognizable precursor cell
Mature cell in bone marrow and blood

Platelet formation

Platelets are formed through megakaryocyte demarcation membranes:

An estimated 1000-5000 platelets are produced from each megakaryocyte.
In normal adults, platelet production is ~35,000-50,000/microL of whole blood per day.
This value can increase 8-fold during times of increased demand.

Platelets in the circulation

The balance of influx, efflux, and redistribution is crucial:

Thrombopoietin regulates platelet count.
Platelets undergo circulating destruction or removal, with 70% in the circulation and 30% in the spleen.

Degree of thrombocytopenia

Mild: 140 - 100 x 10⁹/L
Moderate: 100 - 50 x 10⁹/L
Severe: 50 - 20 x 10⁹/L
Very severe: < 20 x 10⁹/L

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