Association between high-normal albuminuria and risk factors for cardiovascular and renal disease in essential hypertensive men.

BACKGROUND Microalbuminuria (overnight urinary albumin excretion [UAE] > 15 microg/min) is associated with cardiovascular risk factors and predicts morbid events in hypertensive subjects. However, albuminuria is not a dichotomous variable, and a relationship with cardiovascular risk factors may extend below that conventional threshold. METHODS We studied 186 never-treated, glucose-tolerant, normalbuminuric (overnight UAE < or = 15 microg/min), essential hypertensive men with normal renal function (serum creatinine < 1.4 mg/dL). Study variables were 24-hour ambulatory blood pressure (BP), cardiac structure and geometry (by echocardiography), body weight, fasting insulin levels, insulin sensitivity (the Homeostasis Model Assessment index), and creatinine clearance (from overnight collections or through the Cockcroft formula) analyzed as a function of ascending urine albumin quartiles (cutoff values, 4.3, 6.3, and 9.4 microg/min; n = 47, 45, 47, and 47, respectively). RESULTS As compared with the three bottom fourths, patients with high-normal albuminuria (albumin, 9.4 to 15 microg/min) had a greater 24-hour BP, greater relative wall thickness, more frequent concentric left ventricular hypertrophy, heavier body size, increased fasting insulin levels, reduced insulin sensitivity, and greater creatinine clearance. CONCLUSIONS High-normal albuminuria in uncomplicated essential hypertensive men is associated with an adverse cardiovascular and metabolic risk profile. Furthermore, hyperfiltration in the presence of minimally increased albuminuria may underlie an augmented glomerular blood flow and hydraulic pressure conducive to glomerular hypertension and, eventually, renal insufficiency. Overall, these data confirm the appropriateness to shift downward the limits for diagnosing microalbuminuria in essential hypertension, as indicated from previous prospective studies.