isosthenuria

[ī-sŏs′thə-nurē-ə, ī′sō-sthĕ-]
n.
  1. A condition in chronic renal disease in which the kidneys cannot form urine with a higher or a lower specific gravity than that of protein-free plasma.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.