Proposal of a new formula to calculate total urinary nitrogen from urea urinary nitrogen

A. Palmo, L. Ombra, P. Massarenti, A. De Nicola, L. Gavassa, F. Veglia, F. Balzola

Research output: Contribution to journalArticlepeer-review


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 × 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.

Original languageEnglish
Pages (from-to)45-47
Number of pages3
JournalClinical Nutrition
Issue number1
Publication statusPublished - 1989

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Critical Care and Intensive Care Medicine
  • Endocrinology, Diabetes and Metabolism
  • Gastroenterology
  • Health Professions(all)


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