Definition

Acquired platelet function defects are diseases or conditions that cause the blood elements needed for blood clotting (platelets) to not work properly. The term "acquired" means these diseases or conditions are not present at birth.

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Alternative Names

Acquired qualitative platelet disorders; Acquired disorders of platelet function

Causes, incidence, and risk factors

With platelet disorders, there may be too many or too few platelets, or platelets that do not function well. Some conditions cause changes in both the number and function of platelets. Any platelet disorder affects blood clotting.

These disorders can be present at birth (congenital), or they may develop later because of another disease or condition, or without a known cause. In many cases, the platelet count may be normal or even high, but there will be evidence of a bleeding disorder.

Disorders that can cause problems in platelet function include:

• Chronic myelogenous leukemia
• Myelofibrosis
• Polycythemia vera
• Primary thrombocythemia

Other causes include:

• Kidney (renal) failure
• Multiple myeloma
• Medications such as aspirin, ibuprofen and other anti-inflammatory drugs, penicillins, phenothiazines, and prednisone (after long-term use)

Symptoms

• Abnormal menstrual periods
  • Heavy menstrual periods
  • Prolonged menstrual bleeding (more than 5 days per menstrual period)
• Abnormal vaginal bleeding
• Bleeding in the urine
• Bleeding under the skin or in the muscles (soft tissues)
• Gastrointestinal bleeding
  • Bloody, dark black, or tarry bowel movements
  • Vomiting blood or material that looks like coffee grounds
• Nosebleeds
• Prolonged bleeding, easy bruising
• Skin rash
  • Bruises
  • Pinpoint red spots (petechiae)

Signs and tests

• Bleeding time
• Platelet aggregation test
• Platelet count
• PT and PTT

Treatment

Treatment is aimed at the cause of the problem.

• Bone marrow disorders (which may have abnormally low or high numbers of platelets) are treated with platelet transfusions, removing platelets from the blood (platelet pheresis), or chemotherapy to treat the condition.
• Platelet function defects caused by kidney failure are treated with dialysis or a drug called desmopressin (ddAVP).
• Platelet problems caused by medication are treated by stopping the medication.

Expectations (prognosis)

Treating the cause of the problem usually corrects the defect.

Complications

• Prolonged bleeding
• Severe anemia

Calling your health care provider

Call your health care provider:

• If you have bleeding and do not know the cause
• If your symptoms get worse or do not improve after you are treated for an acquired platelet function defect

Prevention

Using medications carefully can reduce the risk of drug-related acquired platelet function defects. Treating other disorders may also reduce the risk. Some cases are not preventable.

References

Lopez JA, Lockhart E. Acquired disorders of platelet function. In: Hoffman R, Benz EJ, Jr, Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier;2008:chap 142.

McMillan R. Hemorrhagic disorders: Abnormalities of platelet and vascular function. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 179.

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