What is the medical term for an abnormally low platelet count?

The medical term for an abnormally low platelet count is thrombocytopenia.

Platelets, or thrombocytes, are tiny blood components that gather at damaged blood vessels and help form clots. In adults, a typical platelet count is roughly 150,000 to 450,000 platelets per microliter of blood, although laboratory ranges can vary. Thrombocytopenia means the count is below the expected range; its severity and clinical significance depend on the number, the cause, and whether bleeding is present.

The condition can arise because the bone marrow makes too few platelets, the immune system or another process destroys them too quickly, or an enlarged spleen holds onto too many. Causes include infections, certain medications, liver disease, leukemia, immune thrombocytopenic purpura, and thrombotic thrombocytopenic purpura.

A common mix-up is with anemia, which concerns too few red blood cells or too little hemoglobin. Leukopenia means a low white blood cell count, while polycythemia generally refers to an abnormally high red blood cell concentration. Thrombocytopenia may cause easy bruising, nosebleeds, gum bleeding, or pinpoint skin spots called petechiae, but some cases produce no symptoms and are found on a routine complete blood count.