Excretion of N1, N12-diacetylspermine in the urine of healthy individuals

Background: Urinary N-1, N-12 -diacetylspermine (DiAcSpm) is a novel tumour marker that can be used to detect early cancers. In this study, we examined whether spot urine samples could represent the daily excretion of DiAcSpm after creatinine normalization and which factors should be taken into account in determining reference values for this biomarker. Methods: We collected the following urine samples: (1) samples from seven healthy volunteers collected on each day of two 2-day sessions to examine the circadian variation of DiAcSpm excretion; (2) samples from 3952 male and 1782 female volunteers to estimate the DiAcSpm concentrations in apparently healthy adults and (3) samples from 16 female volunteers collected every morning over a 3-month period to examine the menstruation-related variation in DiAcSpm excretion. The DiAcSpm concentrations were determined by enzyme-linked immunosorbent assay or a colloidal gold aggregation procedure using DiAcSpm-specific antibodies. Results: (1) The circadian variation of DiAcSpm in the urine was greatly diminished after creatinine normalization. (2) DiAcSpm was higher in females than in males, and the creatinine-normalized medians (95th percentile) of the urinary DiAcSpm concentrations were 149 (305) and 100 (192) nmol/g creatinine for females and males, respectively. (3) The mean concentrations of urinary DiAcSpm were lower after menstruation than before menstruation by approximately 30 nmol/g creatinine. Conclusion: Spot urine samples obtained at any time of a day may be used to estimate the daily excretion of DiAcSpm in nmol DiAcSpm per gram creatinine. Sex, age and menstrual condition should be considered when determining the reference values for urinary DiAcSpm.