¹Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan

Correspondence: T Konta, Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, 2-2-2, Iida-Nishi, Yamagata 990-9585, Japan. E-mail: kkonta@med.id.yamagata-u.ac.jp

Received 14 September 2005; Revised 17 January 2006; Accepted 10 February 2006; Published online 28 June 2006.

Abstract

Microalbuminuria, an indicator of glomerular injury, is associated with increased risk of progressive renal deterioration, cardiovascular disease, and mortality. However, the prevalence of microalbuminuria in Japanese general population is less certain. Thus, we examined the prevalence of microalbuminuria and its associated risk factors in Japan. Subjects of this cross-sectional study were asymptomatic individuals over 40 years in Takahata, Japan. Urine albumin–creatinine ratio was calculated from a single-spot urine specimen collected in the morning. Creatinine clearance (CCr) was obtained by Cockcroft–Gault equation. Multivariate logistic regression analysis was used to determine which risk factors (i.e., age, hypertension, diabetes, obesity, and salt intake) might predict the presence of microalbuminuria. A total of 2321 subjects (mean age, 64 years; men, 1034; women, 1287) were entered into the final analysis. Among them, the prevalence of microalbuminuria, macroalbuminuria, and proteinuria by dipstick test (1+) were 317 (13.7%), 39 (1.7%), and 103 (4.4%), respectively. Age, hypertension, and diabetes were independently associated with microalbuminuria in men. In addition to the classical risk factors detected in men, estimated 24-h urinary sodium excretion and uric acid were also independently associated with microalbuminuria in women. Among the 668 subjects with renal insufficiency (CCr <60 ml/min/1.73 m²), the prevalence of microalbuminuria and macroalbuminuria were 119 (17.8%) and 18 (2.7%), respectively. In conclusion, microalbuminuria is prevalent across all age groups and is associated with lifestyle-related risk factors in Japanese general population. However, there are a substantial number of subjects with renal insufficiency accompanying no microalbuminuria.