DEF: inability of the kidneys to produce either a concentrated or a dilute urine; refers to a state in chronic renal disease in which the kidney cannot form urine with a higher or a lower specific gravity (concentration) than that of protein-free plasma; the specific gravity of the urine becomes fixed, irrespective of the fluid intake.
ALTERNATIVE DEFINITION: excretion of urine that has not been concentrated by the kidneys and has the same osmolality as that of protein-free plasma
SYN: urine concentrating defect
SYN: impaired urine-concentrating ability
From J:154321, J:161532, J:149831