Diabetes Care, Vol 22, Issue 7 1158-1164, Copyright © 1999 by American Diabetes Association

ARTICLES

Increased Na+/Li+ countertransport activity may help to identify type 1 diabetic adolescents and young adults at risk for developing persistent microalbuminuria

F Chiarelli, M Catino, S Tumini, M de Martino, A Mezzetti, A Verrotti and M Vanelli
Department of Medicine, University of Chieti, Italy. chiarelli@unich.it

OBJECTIVE: To evaluate whether erythrocyte sodium-lithium countertransport (Na+/Li+ CT) activity may identify adolescents and young adults with childhood-onset of type 1 diabetes to be at greater risk to develop persistent microalbuminuria and incipient diabetic nephropathy. RESEARCH DESIGN AND METHODS: In January 1989, Na+/Li+ CT was measured in 170 normoalbuminuric diabetic adolescents and young adults (age 12-23 years; onset of diabetes before age 18 years; duration of diabetes longer than 7 years). Participants were clinically examined at baseline and biennially thereafter. Na+/Li+ CT activity was measured every 2 years during the 8-year follow-up period. Na+/Li+ CT activity was measured also in parents of diabetic offspring. RESULTS: Over 8 years, 18 (10 male, 8 female) out of 170 patients (10.5%) developed persistent microalbuminuria; no patient developed overt nephropathy. The risk of developing microalbuminuria was higher in children with increased Na+/Li+ CT (using 300 mumol.1 erythrocytes-1.h-1 as the arbitrary cutoff point) (group 1) compared with those with normal Na+/Li+ CT at the beginning of the study (group 2) (18.98 vs. 3.29%, P < 0.01; sensitivity 96.7%; specificity 57.9%). Sex did not influence predictive value, sensitivity, or specificity. Na+/Li+ CT was not significantly correlated with HbA1c or duration of type 1 diabetes. The percentage of offspring with both parents having Na+/Li+ CT activity above the median values was significantly higher in patients in group 1 than in group 2. The odds ratio for the occurrence of microalbuminuria after adjustment for confounding variables (albumin excretion rate [AER], sex, HbA1c, mean blood pressure, cholesterol, triglycerides) in type 1 diabetic adolescents with elevated baseline erythrocyte Na+/Li+ CT was 4.5 (95% CI of 2.1-11.4). CONCLUSIONS: These results confirm those of previous studies and suggest that Na+/Li+ CT may be one of the predictors and risk factors for incipient diabetic nephropathy in adolescents and young adults with onset of diabetes during childhood. Persistently increased Na+/Li+ CT activity may help to identify normotensive, normoalbuminuric patients with type 1 diabetes who are predisposed to develop microalbuminuria and incipient diabetic nephropathy.
CiteULike    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. L. Caramori, Y. Kim, C. Huang, A. J. Fish, S. S. Rich, M. E. Miller, G. Russell, and M. Mauer Cellular Basis of Diabetic Nephropathy: 1. Study Design and Renal Structural-Functional Relationships in Patients With Long-Standing Type 1 Diabetes Diabetes, February 1, 2002; 51(2): 506 - 513. [Abstract] [Full Text] [PDF]

				P. A. Mead, R. Wilkinson, and T. H. Thomas Na/Li Countertransport Abnormalities in Type 1 Diabetes With and Without Nephropathy Are Familial Diabetes Care, March 1, 2001; 24(3): 527 - 532. [Abstract] [Full Text]