thrombopathy

[thrŏm-bŏpə-thē]
n.
  1. A disorder of blood platelets resulting in defective thromboplastin, without obvious change in the appearance or number of platelets.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.