osteopenia

[ŏs′tē-ə-pēnē-ə]
n.
  1. A condition of bone in which there is a generalized reduction in bone mass that is less severe than that in osteoporosis, caused by the resorption of bone at a rate that exceeds bone synthesis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.