Cystatin C and Beta-2-microglobulin in diabetic and hypertensive nephropathy and their effect on chronic kidney disease

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Diabetic and hypertensive nephropathies are the major cause of chronic kidney disease and the number one cause of cardiovascular deaths worldwide. Glomerular filtration rate (GFR) is an important indicator of kidney function, essential for diagnosing, evaluating and managing chronic kidney disease (CKD). GFR can be estimated using creatinine and serum cystatin C. However, the estimation of GFR by using serum creatinine is documented to be affected by various factors such as age, sex and mass in the muscle and has led to the misclassification of CKD patients. The study therefore sought to evaluate the value and possible clinical applications of cystatin C and Beta 2 microglobulin as biomarkers for changes in GFR. The study adopted a cross-sectional design which involved 182 patients who had diabetes and or hypertension. The area under the curve (AUC) for Cystatin C for DM was 0.861, HTN was 0.731 and DM+HTN was 0. 758.The area under curve (AUC) for B2M for DM was 1.00, HTN was 0.8373 and DM+HTN was 0. 896.. The area under curve (AUC) for Cys C/B2M for DM was 0.765, HTN was 0.614 and DM+HTN was 0.757. There was a significant negative correlation (r= -0.947; p=0.004) between eGFR and age among participants with DM. Significant negative correlation was observed between eGFR and urea (r= -0.624; p=0.04), Total protein (r= -0.692; p=0.018), uric acid (r= -0.792; p=0.004) and Beta 2 Microglobulin (r= -0.743; p=0.009) among participants with HTN. There was a significant negative correlation between eGFR and age (r= -0.525; p=0.010), urea (r= -0.786; p<0.0001), uric acid (r= -0.464; p=0.026), cystatin C (r= -0.761; p<0.0001) and Beta 2 Microglobulin (r= -0.901; p<0.0001) among participants with both DM+HTN. Among diabetic (DM) participants without CKD, eGFR correlated negatively with age (r= -0.705; p=0.0002), and cystatin C (r= -0.587; p=0.003). Among hypertensives (HTN) participants without CKD, eGFR correlated negatively with age (r= -0.337; p=0.025), total protein (r= -0.361; p=0.016), cystatin C (r= -0.339; p=0.025) and Beta 2 Microglobulin (r= -0.429; p=0.004). eGFR negatively correlated with age (r= -0.505; p<0.0001), urea (r= -0.264; p=0.0214), uric acid (r= -0.264; p=0.021), cystatin C (r= -0.520; p= <0.0001) and Beta 2 Microglobulin (p= -0.500; p<0.0001). Serum Cystatin C and Beta 2 microglobulin have acceptable and significant sensitivities and therefore can be used as markers for renal impairment.
A thesis submitted in fulfillment of the requirements for the degree of Master of Philosophy in the Department of Molecular Medicine, School of Medical Sciences