The Osmotic Concentrating Ability in Healthy infants and Children

Open Access
Publisher Website
Google Scholar
Abstract
A concentrating test was carried out in 212 children aged from 3 days to 18 yrs by giving them a solution of 1/2 dried milk, 1/2 water, sugar, and limited to the usual intake of calories. Urine was collected at 3 hr intervals, and maximum osmolality of the urine was taken as the highest value found in the separate urine samples. This maximum urine osmolality increases with age from birth to puberty. The average maximum urine osmolality values increase rapidly in the 1st months of life and then the increase is slower. There are significant differences between the average values of maximum urine osmolality on the 3rd day (515 mOsm./l.), the 6th day (663 mOsm./l.), the 1st month excluding the 1st week (896 mOsm./l.), the end of the first year (1,118 mOsm./l. at 10-12 months), and at puberty (1,362 mOsm./l. at 14-18 yrs). The regression line has an exponential character (Y = 1,400 x (1[long dash]0.943 x t-0.325)).