What are storage pool deficiencies?
Storage pool deficiencies are a group of bleeding disorders caused by problems with platelet granules. Granules are little sacs inside the platelet where proteins and other chemicals are stored.
Platelets are used by our bodies to create something like an internal bandage (a temporary patch) to stop bleeding. This is called a platelet plug. During the process of making a platelet plug, the platelets change shape. Chemicals inside the granules are pushed out into the bloodstream. These chemicals signal other platelets to come and help. The chemicals also allow the platelets to stick together and stick to the blood vessel to repair it and hold the platelet plug in place. If this doesn’t happen, a good platelet plug cannot form and the body could bleed too much. The chemicals inside the granules also cause injured blood vessels to constrict (tighten) to help stop bleeding.
There are two types of granules: dense granules and alpha granules. The most common deficiencies are caused when platelets fail to empty the contents of the granules into the bloodstream. But, some storage pool deficiencies are caused by a lack of granules.
- Delta storage pool deficiency is caused by a lack of dense granules and the chemicals normally stored inside them. Without these chemicals, platelets are not activated properly and the injured blood vessel does not constrict to help stop bleeding. This type of bleeding problem can be a feature of other inherited conditions (such as Hermansky-Pudlak syndrome and Chediak-Higashi syndrome).
- Gray platelet syndrome is a very rare platelet function disorder caused by a lack of alpha granules and the chemicals normally stored inside them. It is called gray platelet syndrome because the platelets appear gray under the microscope. Without these chemicals, platelets cannot stick to the blood vessel wall, clump together the way they should, or repair the injured blood vessel.
Symptoms
Symptoms of storage pool deficiencies vary from one person to the next, but they are usually mild to moderate.
People with storage pool deficiencies may have the following:
- Easy bruising
- Nose bleeds
- Bleeding from gums
- Heavy or prolonged menstrual bleeding or bleeding after childbirth
- Abnormal bleeding after surgery, circumcision, or dental work
Diagnosis
The diagnosis of storage pool deficiencies requires a careful medical history and a series of tests that should be performed by a specialist at a hemophilia treatment center.
In people with storage pool deficiencies:
- Platelets do not clump together the way they should in special laboratory tests; and
- Granules may not be visible when platelets are looked at with an electron microscope.
Treatment
Most people with storage pool deficiencies only need treatment during surgical procedures (including dental work) and after injury or trauma. When needed, storage pool deficiencies may be treated with the following:
- Antifibrinolytic drugs, which are used to help stop bleeding
- Desmopressin, which can help increase clotting factor but may not be useful in alpha granule deficiency
- Platelet transfusions
People with inherited platelet disorders should not take aspirin, nonsteroidal anti-inflammatory drugs (such as ibuprofen and naproxen), and blood thinners. All of these drugs can make bleeding symptoms worse.
