title: Estimation of renal tubular secretion in man, in health and disease, using endogenous N-1-methylnicotinamide.
abstract: We have been investigating the possibility of using the renal clearance of endogenous N-1-methylnicotinamide (NMN) as a marker of renal tubular function. Sixty-three subjects (11 healthy volunteers and 52 patients with renal impairment) were used for this study. The subjects were divided into three groups according to their creatinine clearance: group 1, over 80 ml/min; group 2, between 30 and 80 ml/min, and group 3, less than 30 ml/min. The correlation between NMN and creatinine clearance was compared for each group. A good correlation (r = 0.84) was found for groups 1 and 3 (r = 0.76), whereas for group 2, a poor correlation was found (r = 0.43). For subjects with mild renal impairment (group 2), there was clear evidence of glomerulo-tubular imbalance manifest by a larger variability in NMN clearance than creatinine clearance and an essentially non-parallel decline in these two parameters for this group. When all subjects were grouped together, the relationship between the clearance of NMN and of creatinine was best described by a 3-term polynomial equation (r = 0.93). NMN clearance is a potentially useful non-invasive marker of renal tubular function in man and provides additional information to that provided by the measurement of creatinine clearance alone. This substance should be more fully evaluated as a potential diagnostic aid.
authors.affiliation: Department of Pharmacy, University of Manchester, UK.
authors.forename: A
authors.initials: A
authors.lastname: Maïza
authors.forename: S
authors.initials: S
authors.lastname: Waldek
authors.forename: F W
authors.initials: FW
authors.lastname: Ballardie
authors.forename: P T
authors.initials: PT
authors.lastname: Daley-Yates
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood / Q000652:urine; D003401:Creatine / Q000097:blood / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007674:Kidney Diseases / Q000097:blood* / Q000175:diagnosis / Q000652:urine*; D007684:Kidney Tubules / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine
chemical_list: D015415:Biomarkers; D009536:Niacinamide; D003401:Creatine; C024058:N(1)-methylnicotinamide