thrombocytopenia
Concise Oxford English Dictionary © 2008 Oxford University Press:
thrombocytopenia /ˌθrɒmbə(ʊ)ˌsʌɪtə(ʊ)ˈpiːnɪə/
▶noun Medicine deficiency of platelets in the blood, leading to bleeding into the tissues, bruising, and slow blood clotting after injury.
'thrombocytopenia' also found in these Oxford entries:

