Chiarelli F, Catino M, Tumini S, de Martino M, Mezzetti A, Verrotti A, Vanelli M
Department of Medicine, University of Chieti, Italy.
Diabetes Care. 1999 Jul;22(7):1158-64. doi: 10.2337/diacare.22.7.1158.
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.
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.
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).
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.
评估红细胞钠-锂逆向转运（Na⁺/Li⁺ CT）活性是否可识别儿童期发病的1型糖尿病青少年和青年成人，判断其发生持续性微量白蛋白尿和早期糖尿病肾病的风险是否更高。
1989年1月，对170例正常白蛋白尿的糖尿病青少年和青年成人（年龄12 - 23岁；糖尿病发病年龄在18岁之前；糖尿病病程超过7年）进行Na⁺/Li⁺ CT检测。参与者在基线时进行临床检查，此后每两年检查一次。在8年随访期间，每2年测量一次Na⁺/Li⁺ CT活性。还对糖尿病患者的父母进行了Na⁺/Li⁺ CT活性检测。
在8年期间，170例患者中有18例（10例男性，8例女性）（10.5%）出现持续性微量白蛋白尿；无患者发展为显性肾病。与研究开始时Na⁺/Li⁺ CT正常的患者（第2组）相比，Na⁺/Li⁺ CT升高（以300 μmol·1红细胞⁻¹·h⁻¹作为任意切点）的儿童（第1组）发生微量白蛋白尿的风险更高（18.98%对3.29%，P < 0.01；敏感性96.7%；特异性57.9%）。性别不影响预测价值、敏感性或特异性。Na⁺/Li⁺ CT与糖化血红蛋白（HbA1c）或1型糖尿病病程无显著相关性。第1组患者中父母双方Na⁺/Li⁺ CT活性均高于中位数的后代百分比显著高于第2组。在调整混杂变量（白蛋白排泄率[AER]、性别、HbA1c、平均血压、胆固醇、甘油三酯）后，基线红细胞Na⁺/Li⁺ CT升高的1型糖尿病青少年发生微量白蛋白尿的优势比为4.5（95%可信区间为2.1 - 11.4）。
这些结果证实了先前研究的结果，并表明Na⁺/Li⁺ CT可能是儿童期发病的青少年和青年成人早期糖尿病肾病的预测指标和危险因素之一。持续升高的Na⁺/Li⁺ CT活性可能有助于识别易发生微量白蛋白尿和早期糖尿病肾病的血压正常、白蛋白尿正常的1型糖尿病患者。
