Urine concentrating capacity in women: the results of a screening method in a population study.

Urine concentration tests were performed as part of a population study in 1405 women in age strata between 38 and 60 years. The measurement of urine osmolality from the 13th hour of fluid deprivation overnight was adopted as a screening test. If an osmolality of 600 mOsm/kg H2O was not attained, a second test was performed and if this was abnormal a pitressin tannate test was carried out (54 women). Among women with a low urine concentration after pitressin tannate (less than 700 mOsm/kg H20) all but one suffered from chronic renal disease. The urine concentration capacity decreased with age illustrating the inadequacy of using the same "normal" limits at different ages. The outcome of the study raises the question of whether one simple fluid deprivation test discriminates tubular damage sufficiently satisfactorily to justify its application to the screening of large groups of people.