title: Proposal of a new formula to calculate total urinary nitrogen from urea urinary nitrogen.
abstract: Urea urinary nitrogen (UUN) and total urinary nitrogen (TUN) were determined in 15 patients to study their relationship mainly in highly catabolic patients. The subjects were: 7 multiple trauma, 3 autologous bone-marrow transplant, 1 tetanus, 4 postcholecystectomy patients; 180 determination were made, 111 of which in highly catabolic phase (TUN > 15 g/day). TUN and UUN are well correlated (r = 0.9742; p < 0.001) in the range 3 to 52 g/ day of TUN. Urea represents the 83.2 +/- 9.4% (M +/- SD). A double-linear formula to calculate TUN from UUN is proposed (for UUN 15 g/ day: TUN = UUN x 1.17 + 0.7; for UUN > 15 g/ day: TUN = UUN + 4). The least square procedure was used to compare the differences between measured and calculated TUN, and the results obtained with the proposed double-linear formula were compared with that obtained employing pre-existing formulas (Lee's and Mackenzie's). Considering all ranges of values studied (3-52 g of TUN) the results obtained were significantly different (p < 0.005); dividing the levels of TUN in 15 g; 16-29 g and 30 g, the results were always better, but the statistical significancy was not always reached.
authors.affiliation: Department of Dietetics and Clinical Nutrition, Ospedale S. Giovanni, Turin, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Palmo
authors.forename: L
authors.initials: L
authors.lastname: Ombra
authors.forename: P
authors.initials: P
authors.lastname: Massarenti
authors.forename: A
authors.initials: A
authors.lastname: De Nicola
authors.forename: L
authors.initials: L
authors.lastname: Gavassa
authors.forename: F
authors.initials: F
authors.lastname: Veglia
authors.forename: F
authors.initials: F
authors.lastname: Balzola