Prevalence of and clinical characteristics associated with microalbuminuria in hypertension

Cardiovascular disease is the leading cause of mortality. As blood pressure is one of the most important risk factors for cardiovascular disease, effective management of hypertension is critical in reducing this risk. In addition to high blood pressure, however, several factors have been identified as predictors of future cardiovascular events. These include high cholesterol, cigarette smoking, obesity and diabetes. Taken together, these traditional risk factors do not entirely explain the risk. Thus, many novel risk factors have been proposed for risk prediction of cardiovascular disease. Microalbuminuria is one such factor. Microalbuminuria is defined as excretion of albumin in the urine above the normal level but less than gross proteinuria. As excretion of albumin exhibits high variability due to many confounders (such as urinary tract infection and strenuous exercise), diagnosis of microalbuminuria should be ideally based on screening of multiple samples using either 24-hour urine collection or first-morning voids. Much evidence suggests that microalbuminuria is a reflection of generalised endothelial dysfunction. This is supported by the observation that microalbuminuria is strongly associated with cardiovascular disease. My main aim was to study microalbuminuria in people with hypertension attending specialist clinics. Microalbuminuria has been investigated extensively in diabetes and in patients with renal disease. However, the available information on the association of microalbuminuria with hypertension has many limitations since many studies had small sample size, restricted population or were confounded by potential misdiagnosis of microalbuminuria by the use of single samples. This has led to uncertainty about the prevalence of microalbuminuria in hypertension, where reported prevalence ranges from 4.7% to 58%, and probable underestimation of its clinical significance. I addressed these issues by conducting a series of studies in 1059 hypertensive subje