Thus, the increased level of dopamine glucuronide observed in our study may be a potential biomarker involved in the onset of CKD-MBD.13 It has been reported that serotonin increases the PTH effect on activating protein-1 activity, particularly on the regulation of collagenase expression.14 The increased N-acetylserotonin glucuronide in high-PTH patients may indicate that serotonin may be involved in the development of CKD-MBD. The gene discussed is PTH; the disease is chronic kidney disease.