thrombocytopenia
Meaning of thrombocytopenia: Three mechanisms cover nearly all of it: too few made, too many destroyed, or too many held back in the spleen.
Definition of thrombocytopenia
Thrombocytopenia is a platelet count below the normal range. Platelets are small fragments shed by large cells in the bone marrow, and they plug damage in vessel walls and set the clotting process going. When too few circulate, minor injuries bleed for longer, bruises appear readily, and at very low counts bleeding can start without any injury at all.
How thrombocytopenia is built
- thromb/o Combining form · Greek clot, clotting
- cyt/o Combining form · Greek cell
- -penia Suffix · Greek deficiency, abnormally low count
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
What causes it?
| Mechanism | What is happening | Examples |
|---|---|---|
| Reduced production | The bone marrow makes too few | Chemotherapy, marrow disease, severe alcohol use, some vitamin deficiencies |
| Increased destruction | Platelets are removed faster than they are replaced | Immune destruction, certain drugs, some infections |
| Sequestration | An enlarged spleen holds a large share out of circulation | Advanced liver disease with a large spleen |
| Dilution or consumption | Platelets used up or diluted away | Massive bleeding and transfusion, widespread clotting |
Sorting between these is the point of the investigation, since the categories lead in completely different directions. A blood cell count showing a low platelet number alone suggests something different from one in which red and white cells have fallen too, which points back toward the marrow itself.
What does it look like?
Bleeding from a platelet problem has a characteristic pattern. Pinpoint red or purple spots appear on the skin, especially on the lower legs, and do not fade when pressed. Larger flat purple patches follow. Bleeding tends to come from surfaces rather than deep in the body: nosebleeds, bleeding gums, heavier menstrual periods, prolonged oozing from a small cut. That contrasts with a clotting factor deficiency, which more typically causes bleeding into joints and muscles. How low the count goes matters more than the cause for predicting bleeding, and moderate reductions often produce nothing noticeable at all.
Can a low count be false?
Yes, and it is a well known trap. The chemical used to keep blood from clotting in the collection tube causes platelets to clump together in a small number of people. The analyzer counts each clump as a single cell and reports a low result, though the person has a perfectly normal count. Examining a blood film shows the clumps directly, and repeating the test in a tube containing a different anticoagulant gives the true number. There is also a form of destruction driven by heparin that is unusual in the opposite direction: the count falls, yet the risk that follows is clotting rather than bleeding.
Used in a sentence
A complete blood count revealed thrombocytopenia, prompting further evaluation of the underlying cause.
Good to know
Whether a low platelet count reflects reduced production, increased destruction or trapping in the spleen is established by further testing, since the categories point toward entirely different underlying conditions.
Word origin
Where “thrombocytopenia” comes from
Formed from thrombo-, Greek for clot, kytos, meaning cell, and -penia, meaning deficiency or poverty.