Impaired renal concentrating ability

What it means

A defect in the ability to concentrate the urine.

An impairment in renal concentrating ability can be easily recognized by the maximum concentrating ability (Umax) as determined by the urine osmolality reached after a fixed period of dehydration. Inability to maximally concentrate the urine is related to one or both of two basic tubular defects: 1) a failure of maximal free-water generation by the diluting segment in the ascending limb of Henle's loop; and 2) a failure of the distal tubular epithelium to achieve maximum permeability to water during water deprivation.

Rare diseases that can present with this2

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Urine concentrating defect · Urine concentration defect