Stratification enhances sensitivity of reference values for serum urea

To determining the influence of age and gender on reference values for serum urea and electrolytes in north central Nigeria, 480 consented healthy adults (reference individuals) were selected using standard inclusion and exclusion criteria from the locality the Hospital serves. Subjects were stratified by age and sex. Serum urea was determined by Fearon's Method and serum electrolytes determined by flame emission spectrophotometer. Ratio of subgroup standard deviation exceeding 1.5, known physiological difference between subgroups and difference of subgroups' mean values of statistical difference at 0.05 probability were used to categorize health associated reference values for serum urea and electrolytes. Results indicated that reference values for serum urea in North Central Nigeria require stratification by age. However, the sex difference observed for serum urea was not significant enough to justify separate reference values. All the age and sex groups studied had similar reference values for the electrolytes studied. We therefore concluded that enhancing the sensitivity of health associated reference values for serum urea in north central Nigeria would require stratification by age. Keywords: adult reference values, stratification, urea and electrolytes The Tropical Journal of Health Sciences Vol. 13(2) 2006: 24-2