Estimation of microalbuminuria and advanced glycation end products by immunoassays in diabetes mellitus, hypertension and pregnancy induced hypertension for the early diagnosis of nephropathy

The prevalence of non-communicable diseases like diabetes mellitus (DM) and hypertension (HTN) is growing worldwide. Both the diseases are associated with development of nephropathy if not controlled effectively. Microalbuminuria (MAU) is recognised as an excellent predictor for nephropathy in above mentioned diseases. Additionally, the timely detection of Advanced Glycation End Products (AGEs) is also emerging as an important prognostic factor for diabetic and non-diabetic nephropathies. The early screening for MAU and AGEs by immunoassays represents a useful and relatively inexpensive clinical tool to control the nephropathy incidence in such circumstances. The study subjects comprised of DM (n = 182), HTN (n = 50) and PIH (n = 70) groups. Diabetic and hypertensive patients were selected from B.A.R.C. hospital and PIH subjects were selected from K.E.M and Vashi Municipal Hospital. The early morning urine samples and blood samples were collected from all the patients for MAU and serum AGEs estimation respectively. MAU levels were estimated by in-house RIA kit. MAU-RIA kit consisted of HSA standards ranging from 0 to 200 μg/ml, ¹²⁵I labeled HSA and anti-albumin antibodies coupled to magnetic particles. The serum CML levels were estimated by in-house RIA. The CML-RIA consisted of CML-BSA standards covering a range of 0-0.5 μg/ml, ¹²⁵I labeled CML-BSA and anti CML-KLH antibodies. The serum total AGEs levels were determined by commercial ELISA kit. The levels of MAU, CML and AGE-BSA were significantly higher (P < 0.001) in DM, HTN and PIH patients than controls. The prevalence of MAU was 30%, 22% and 70% in DM, HTN and PIH subjects studied in this study indicating that these subjects were at risk to develop nephropathy. The median levels of MAU in normal, diabetic, hypertensive and PIH subjects were 0.8, 15.7, 17.5 and 39 μg/ml respectively. The MAU levels ranged from 0-30, 0-281, 0-276 and 12-91 μg/ml in normal, DM, HTN and PIH subjects respectively. The mean CML levels were 0.10 ± 0.06, 0.38 ± 0.12, 0.31 ± 0.14 and 0.25 ± 0.06 μg/ml in normal, DM, HTN and PIH subjects respectively and the mean AGE-BSA levels were 1.03 ± 0.23, 1.95 ± 0.81, 1.4 ± 0.36 and 1.76 ± 0.59 μg/ml in normal, DM, HTN and PIH subjects respectively. Upon comparison, MAU and AGE-BSA levels showed reasonably better correlation when compared to MAU and CML levels. Increased MAU and AGEs levels in DM, HTN and HTN subjects indicated that they were susceptible to develop renal complications. Early diagnosis of nephropathy risk by MAU and AGEs-detection by immunoassays would be more practicable than using tedious analytical techniques. It will help clinicians in identifying and regular screening of high-risk subjects. Eventually, the timely renoprotective measures would certainly reduce incidence of nephropathy in diabetes as well as in hypertension and PIH. (author)