Symmetric dimethylarginine, an endogenous marker of glomerular filtration rate, and the risk for microalbuminuria in young people with type 1 diabetes.
OBJECTIVE
To perform a cross-sectional comparison of endogenous markers of glomerular filtration rate (GFR) (plasma symmetric dimethylarginine (SDMA) and estimated GFR (eGFR)) with a direct measure of GFR (using the plasma clearance of Inutest (In-GFR)), and a longitudinal evaluation of these markers in relation to the development of microalbuminuria, in young people with type 1 diabetes (T1D).


METHODS
Longitudinal stored blood samples (n=1105) were available from 417 young people from the Oxford Regional Prospective Study (an inception cohort of 527 children followed for a median of 10.3 (interquartile range 7.1-12.3) years), for measurement of SDMA and creatinine. Additional annually collected data on anthropometric parameters, HbA1c, insulin dose and three early morning albumin:creatinine ratios were available. In-GFR was measured in a representative subgroup of 183 subjects.


METHODS
SDMA and eGFR.


RESULTS
SDMA and eGFR were significantly and similarly associated with In-GFR (r=-0.38 and r=0.36, p<0.001). Overall SDMA levels were lower in microalbuminuric (n=116) than normoalbuminuric subjects (n=301) (0.385 + or - 0.063 vs 0.412 + or - 0.059 micromol/l, p<0.001), probably reflecting hyperfiltration. The pattern of change in SDMA levels with age differed between microalbuminuric and normoalbuminuric subjects. Whereas SDMA levels declined in both groups until the age of 16 years, thereafter they tended to rise only in microalbuminuric subjects, probably reflecting a decline in renal function.


CONCLUSIONS
In this longitudinal study of young people with T1D, measurement of SDMA, in contrast to eGFR, proved to be a reliable marker in identifying changes in filtration rates associated with the development of microalbuminuria (MA).
Marcovecchio
M Loredana
ML
Department of Paediatrics and Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
Dalton
R Neil
RN
Turner
Charles
C
Prevost
A Toby
AT
Widmer
Barry
B
Amin
Rakesh
R
Dunger
David B
DB
D000293:Adolescent; D017668:Age of Onset; D000419:Albuminuria / Q000097:blood / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood; D015415:Biomarkers / Q000097:blood; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000097:blood / Q000453:epidemiology / Q000503:physiopathology; D018450:Disease Progression; D004739:England / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D011379:Prognosis
D015415:Biomarkers; C024917:symmetric dimethylarginine; D001120:Arginine