| ObjectiveRecent clinical studies among general population have shown that an even mild increase of homocysteinemia plays an important role in the progression of macrovascular and microvascular disease in patients with type 2 diabetes. It is well documented that plasma tHcy concentrations correlated inversely with glo-merular filtration rates. However, whether fasting plasma homocysteine (Hcy) levels are related to the function of renal tubule haven t been fully elucidated. The present study focused on the role of renal tubule in homocysteine metabo-lism.MethodsPatientsThe control subjects(22 healthy individuals: 12 men and 10 women; mean age,51.23 13. 26 years) were selected from healthy subjects participating in a health check program. 58 patients(26 men,32 women; mean age, 54.38 12.26 years) with type 2 diabetes mellitus ( DM) whose urinary albumin excretory rate < 30mg/24h and 22 healthy controls ( 12 men, 10 women; mean age, 52. 00 13.48 years) were selected. DM group were divided into three groups according to urinary Tamm - Horsfall protein excretory rate ( UTHER) ; (1)DM - I group: UTHER 13.70mg/24h - 43.98mg/24h; (2)DM - II group: UTHER > 43.98mg/ 24h; (3)DM - I group: UTHER < 13.70mg/24h.MethodFasting plasma total Hcy levels were measured by chemiluminescence im-munoassay, reagents and chemiluminescence immunoassay equipment were sup-plied by diagnostic products corporation. Urinary Tamm - Horsfall protein excre-tory rate and urinary alpha -1 - microglobulin levels were measured by radioim-munoassay and reagents were supplied by China atomic energy science academe.Statistical analysisAll values were expressed as means SD. Students t tests, one -way analyses of variance, and x2 tests were appropriately performed for comparison of groups. Univariate linear regression analyses and multiple regression analyses were performed to evaluate the relationship among plasma Hcy levels and various clinical factors. P values less than 0.05 were considered significant.Results1. The controls were matched with the cases in age, sex, BMI, WHR, total cholesterol, triglyceride, blood uria nitrogen and creatinine.2. Mean plasma homocysteine in the DM group was significantly higher than in the normal group (11. 85 5.99 mol/L versus 9.14 2.86 umol/L,P <0. 01). Mean plasma homocysteine in the DM - M group was significantly higher than in the DM - I group and in the normal group (13. 84 6.57 umol/L ver-sus 9.47 2. 65 umol/L and 9.14 2. 86 umol/L,P<0.05).3. Patients whose urinary alpha - 1 - microglobulin levels were higher than normal had higher plasma homocysteine levels, but the difference is not significant.4. Of 15 patients whose plasma homocysteine levels above the normal range (means ?2 SD of values obtained in the control group) ,10 had urinary Tamm - Horsfall protein excretory rate under the normal range ( means 2 SD of valuesobtained in the control group). These patients with hyperhomocysteinemia had higher percentage of low urinary Tamm - Horsfall protein excretory rate (66. 67% vs. 21.54%, P<0.01).5. Spearman relationship analysis between plasma homocysteine levels and clinical parameters showed that plasma homocysteine levels was related with fast-ing plasma insulin levels and fasting plasma C - peptide levels. Multielement stepwise regression analysis showed that fasting plasma insulin levels was the influencing factor of plasma homocysteine levels.Conclusion1. The damage of renal tubule may participate in the increase in homocysteine levels.2. The measurement of plasma homocysteine may contribute to the identification, among the type 2 diabetic population, of renal tubular damage.3. Fasting plasma insulin and c - peptide levels are significant related with fasting plasma homocysteine levels. |
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