Letter Regarding Article by Klausen et al, “Very Low Levels of Microalbuminuria Are Associated With Increased Risk of Coronary Heart Disease and Death Independently of Renal Function, Hypertension, and Diabetes”

Abstract

To the Editor: Klausen et al1 suggest changing the cutoff point for the definition of microalbuminuria to lower levels than are presently used (30 to 300 mg/24 h, or 20 to 200 μg/min). On the basis of their findings, they argue that urinary albumin excretion (UAE) of >5 μg/min in nocturnal collections should be defined as abnormal. We believe that the data provided in their study do not support this argument for the following reasons. First, their study is not designed to reach such a conclusion. The authors found their cutoff point after arbitrarily dividing their population in quartiles of UAE. This is not the appropriate technique to determine a cutoff level because the achieved cutoff value is dependent on the distribution of the parameter within the population under study. Levels of UAE are not normally distributed, so the quartile with the highest values of UAE will comprise individuals with both …