Systematic assessment of urinary catecholamines in type 2 diabetic nephropathy and neuropathy patients by liquid chromatography tandem mass spectrometry

Objective To investigatethe relationship between urinary catecholamine levels and type Ⅱ diabetic nephropathy and neuropathy. Methods Allsubjects were collected fromTongji Hospital, Tongji Medical College, Huazhong University of Science and Technology,and were divided into two groups: type Ⅱ diabetic patients (For 24 h urine, n=130, aged 27-81 years old, 75 men, 55 female; for random urine, n=115, aged 27-77 years old, 75 men, 40 female) and healthy control (For 24 h urine, n=118, aged 27-76 years old, 67 men, 51 female; for random urine, n=93, aged 25-74 years old, 57 men, 36 female).Based on the results of urinary albumin excretion, type Ⅱ diabetic patients were prospectively divided into two independent groups: patients with nephropathy (For 24 h urine, n=37; for random urine, n=32) and patients without nephropathy (For 24 h urine, n=32; for random urine, n=35). According to questionnaires, quantitative sensory testing and autonomic function test, type Ⅱ diabetic patients were divided into two different groups: patients with neuropathy (For 24 h urine, n=31; for random urine, n=23) and patients without neuropathy (For 24 h urine, n=30; for random urine, n=35). Urinary catecholamines(CAs) levels, including epinephrine (E), norepinephrine (NE), dopamine (DA) and total catecholamines (total CAs) levels, were measured using liquid chromatography tandem mass spectrometry (LC-MS/MS). The CAs levels in different groups have been discussed. The results were analyzed using χ2 test, independent t test and Mann-Whitney non-parametric test. Results Type Ⅱ diabetic patients with nephropathy show lower E (0.74±0.24) μg/24 h, NE(9.22±4.02) μg/24 h, DA(64.77±21.68) μg/24 h and total CAs(74.72±25.65) μg/24 h in 24-hour urine in comparison with the group without nephropathy(For E, 4.23±0.50 μg/24 h, U=10, P<0.001; for NE, (32.31±1.74) μg/24 h, t=-2.72, P=0.011; for DA, (219.58±27.51) μg/24 h, t=-2.88, P=0.007; fro CAs, (256.02±30.65) μg/24 h, t=-3.02, P=0.005) and the differences were statistically significant (P<0.05). The differences of NE, DA and total CAs between type Ⅱ diabetic patients with nephropathyand without nephropathy were statistically significant in random urine(P<0.05). Conclusion These results suggested that urine CAs levels in diabetic patients with nephropathy is lower than that in patients without nephropathy, which may be related to the occurrence and development of diabetic nephropathy. Key words: Diabetic nephropathies; Diabetic neuropathies; Diabetes mellitus, type 2; Catecholamines; Chromatography, liquid; Tandem mass spectrometry