Absolute quantification of cholesteryl esters using liquid chromatography-tandem mass spectrometry uncovers novel diagnostic potential of urinary sediment

- Deuterated internal standards are essential for absolute quantification of CEs.
- Urinary CEs are detected specifically in renal disease group.
- CE composition of urinary sediment differs from that of urinary supernatant.

BackgroundUrine has been utilized as a source of biomarkers in renal disease. However, urinary lipids have not attracted much attention so far. Here we studied urinary cholesteryl ester (CE) and its relevance in renal disease.MethodsQuantitative analysis of CE molecular species in serum, urinary supernatant, and urinary sediment from patients with renal disease (N = 64) and non-renal disease (N = 23) was carried out using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and deuterated CEs as internal standards.ResultsValidation study showed good precision and accuracy of LC-MS/MS. Many CE species were detected in the urinary sediment and supernatant in the renal disease group, whereas only a few CE species were detected in the other group. In the renal disease group, the sum of the concentrations of all CE species showed a significant correlation between the sediment and the supernatant from urinary samples (r = 0.876, p < 0.001); however, the composition of CEs was significantly different between them. Further, the composition of CEs of the supernatant was similar to that of the serum.ConclusionsOur LC-MS/MS analysis uncovered a distinct CE profile in urinary sediment from patients with renal disease, suggesting a possible contribution of CEs in urothelial cells to the development of renal disease.