Objective: The purpose of this paper was to study the prevalence of microalbuminuria (MA) in males and females of various ages by applying various diagnostic criteria. Three groups of subjects were studied: apparently healthy individuals; self-reported hypertensives; and diabetics.
Material and methods: A total of 9255 individuals (age > or =20 years), all of whom were identified from the large (n = 65 258) population-based Nord-Trøndelag Health Study (HUNT) performed in Norway between 1995 and 1997, delivered three morning urine samples for MA analysis. Of these individuals, 651 reported both diabetes and treated hypertension, 944 diabetes only and 5547 treated hypertension only. The remaining 2113 subjects without diabetes or treated hypertension were randomly selected. The albumin:creatinine ratio (ACR) was used as an expression of urine albumin excretion.
Results: Applying the classical definition of MA of ACR > or =2.5 mg/mmol in at least two out of three urine samples, the prevalence of MA in those with both diabetes and hypertension was 42.2% in males and 25.9% in females; corresponding values for those with diabetes only were 27.8% and 22.4%, for the hypertensives 19.3% and 11.5% and for the randomly selected sample 5.2% and 4.7%. The prevalence of MA increased strongly with increasing age for both genders in all subgroups. The prevalence of MA changed considerably when applying different cut-off values of ACR and at least one, two or three urine samples with ACRs above the cut-off value.
Conclusions: This study, one of the largest cross-sectional screening studies of MA ever performed, clearly illustrates the consequences of applying different diagnostic criteria. The optimal cut-off levels of MA for the prediction of cardiovascular disease still remain to be properly defined, and more follow-up studies are therefore needed.