Question

NS is a 32-year-old female who has bee sick with a cold virus for 10 days. She states that she had flu symptoms of cough, sore throat, and fatigue. It has been three weeks since the cold, and she continues to be fatigued and finds it hard to get enough energy to do things. She comes into see her MD. NS tells you she has noted that she has been bruising easily. She hit her arm accidentally on the counter and now has a large bruise. She also noted little purple spots all over her hands and chest. On exam you note that she does have a large bruise on her R arm and petechiae and purpura over her chest and hands. He draws some labs work and it comes back a platelet count of 40,000.

1. NS has been diagnosed with idiopathic thrombocytopenic purpura (ITP). Explain what this is and who can get it.

2 Discuss the four mechanisms of thrombocytopenia.

3. What symptoms would you expect to see in a patient with ITP and which tests would be used to confirm the diagnosis.

Answer 1

1. Idiopathic thrombocytopenia purpura :

Deficiency of platelets that occurs when the immune system destroys the body's own platelets

Possibly acute, as in postviral thrombocytopenia, or chronic, as in essential thrombocytopenia or autoimmune thrombocytopenia

Excellent prognosis for acute form; nearly four out of five patients recover without treatment

Good prognosis for chronic form; remissions commonly lasting weeks or years, especially among women

Also called immune thrombocytopenic purpura or ITP

#. Pathophysiology

Platelets are coated with autoantibodies that react to the platelet membrane antigens.

Circulating immunoglobulin (Ig) G molecules react with host platelets, which are then destroyed in the spleen and, to a lesser degree, in the liver.

Platelets are sequestered in the spleen and undergo phagocytosis by mononuclear macrophages, leading to the platelets' shortened lifespan.

Normally, the life span of platelets in circulation is 7 to 10 days. In idiopathic thrombocytopenic purpura (ITP), platelets survive 1 to 3 days or less.

The body attempts to compensate by increasing platelet production, but this compensation is incomplete.

As a result, the shortened lifespan and incomplete compensation leads to a decrease in platelet count.

# Causes by :-

Drug reactions

Immunization with a live virus vaccine

Immunologic disorders

Viral infection

Pregnancy

2. Four mechanism of thrombocytopenia are :-

- decreased platelet production

- decreased survival of platelets

- pooling of blood in the spleen

- intravascular dilation of circulating platelets

3. #. Symptoms :-

Epistaxis

Menorrhagia

Prolonged bleeding from gums or scrapes

Petechiae or ecchymosis

Bleeding into mucous membranes

Gingival bleeding

Bleeding from the GI or urinary tract

Absence of splenomegaly

#. Diagnostic Test Results-Laboratory

Platelet count is less than 75,000/μl.

Bleeding time is prolonged; prothrombin time and partial thromboplastin time are normal.

Complete blood count may reveal lymphocytosis and slight eosinophilia.

Peripheral blood smear reveals normal red blood cells and leukocytes; platelets may appear normal with varying numbers of large platelets.

Hemoglobin level is decreased (if bleeding occurred).

Humoral tests measure platelet-associated IgG (elevated IgG levels in 50% of all patients with ITP).

Bone marrow studies show abundant megakaryocytes (platelet precursor cells) and a circulating platelet survival time of only several hours to a few days.