Analysis of urinary sphingolipids using liquid chromatography‐tandem mass spectrometry in diabetic nephropathy

AIMS/INTRODUCTION: Sphingolipids, such as ceramides and sphingosine, are involved in the pathogenesis of diabetes; however, the modulation of urinary sphingolipids in diabetic nephropathy has not been fully elucidated. Therefore, we aimed to develop a simultaneous measurement system for urinary sphingolipids using liquid chromatography‐tandem mass spectrometry and to elucidate the modulation of urinary sphingolipids in diabetic nephropathy. MATERIALS AND METHODS: We established a simultaneous measurement system for the urinary sphingosine, dihydrosphingosine, and six ceramide species (Cer d18:1/16:0, Cer d18:1/18:0, Cer d18:1/18:1, Cer d18:1/20:0, Cer d18:1/22:0 and Cer d18:1/24:0), and we examined the urinary sphingolipids in 64 type 2 diabetes patients and 15 control participants. RESULTS: The established measurement system for the urinary sphingolipids showed good precision for Cer d18:1/16:0, Cer d18:1/20:0, Cer d18:1/22:0 and Cer d18:1/24:0. We observed that the urinary levels of Cer d18:1/16:0, Cer d18:1/18:0, Cer d18:1/20:0, Cer d18:1/22:0 and Cer d18:1/24:0 were elevated in patients with stage 3 of diabetic nephropathy, and were correlated with urinary biomarkers, such as albumin and N‐acetyl‐β‐d‐glucosaminidase, and sediment score. CONCLUSIONS: Our method is useful for the measurement of ceramide in urine specimens, and urinary ceramides might be associated with the pathological condition of diabetic nephropathy, such as renal tubular injury.