Platelet Storage Pool Deficiency

What is platelet storage pool deficiency?

Platelets store proteins and other chemicals that can be released to stimulate platelets to form a platelet plug and support blood clotting. The proteins and other chemicals are stored in little sacs called granules in the platelet. Two common platelet granules are called dense granules and alpha granules. Chemicals in the granules help carry signals from one end of a platelet to the other. When these granules do not work properly, a person may have a platelet storage pool deficiency. This means platelets cannot form a plug to stop bleeding.

There are different types of platelet storage pool deficiency. Sometimes, there are not enough granules to send the signal. Other times, there are enough granules, but they cannot be put together correctly.

  • Secretory/Release disorders – platelets have normal granules but can’t empty contents of granules into the bloodstream properly.
  • Delta storage pool deficiency – Platelets lack dense granules and don’t have the chemicals necessary to make the injured vessel constrict (narrow) or make platelets activate to stick together and plug the hole to stop bleeding. This can occur in Hermansky-Pudlak and Chediak-Higashi syndrome.
  • Grey platelet syndrome – Platelets lack alpha granules and the chemicals in them, and thus may not be able to stick to the injured blood vessel wall, clump together, or repair the injured blood vessel.

What causes it?

Depending on the type of platelet storage pool deficiency, this can occur in men or women and is inherited from one or both parents. The prevalence of platelet storage pool deficiency is not well known. This is because there is no single lab test that can predict the many disorders.

What are the symptoms?

The symptoms of platelet storage pool deficiency may include:

  • Easy bruising
  • Bleeding from the nose or gums
  • In women, heavy menstrual bleeding or bleeding related to childbirth
  • Excessive bleeding after surgery or injury

How is it diagnosed?

Diagnosis of disorders where platelets aren’t functioning normally is more complicated than diagnosis of clotting factor deficiencies. Screening blood tests that evaluate clotting factors may be normal.

The bleeding time test (not commonly done anymore), which looks at the time it takes for a very small cut to stop bleeding, will be long in patients with many platelet disorders.

A set of very specific tests can be done that specialized laboratories and hematology specialists do to further evaluate the specific platelet disorder. One is called platelet aggregation, where a fresh (not frozen) blood sample is examined to see which chemicals stimulate platelet clumping (aggregating). For platelet storage pool deficiencies, confirming a diagnosis also involves using a very high powered microscope (electron microscope) to look at the granules.

How is it treated?

Patients with platelet storage pool deficiencies may need to have treatment during dental or surgical procedures or after injuries or accidents.

Platelets and other agents may be incorporated into treatment. Patients administered platelets that have normal glycoproteins can develop reactions to the infused platelets. This could result in antibodies or a decreased response to platelets.

People with platelet function disorders should not take any products that impact blood clotting or platelet function. These include nonsteriodal anti-inflammatory drugs like ibuprofen or naproxen, aspirin, and blood thinners.