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February 1990

Identifying Patients With Incipient Diabetic Nephropathy: Should 24-Hour Urine Collections Be Used?

Arch Intern Med. 1990;150(2):373-375. doi:10.1001/archinte.1990.00390140091020

• It is not clear whether 24-hour or overnight urine collections should be used to identify patients with incipient diabetic nephropathy (defined as persistent urinary albumin excretion rate [AER] of 20 to 200 μg/min). We therefore studied diurnal variations in AER in type I diabetics with normal AER (n = 16) and incipient (n=12) and clinical (defined as persistent AER 200 μg/min) nephropathy (n = 12), and in healthy controls (n = 24). In all groups AER was lowest at night. In some patients of all groups, marked diurnal variations were observed. Twenty-fourhour urine collections classified all patients correctly. Overnight urine collections, however, misclassified patients with incipient nephropathy as having normal AER in 4 of 12, 7 of 12, or 3 of 7 cases, depending on which cutoff level was used. We conclude that 24-hour urine collections are more sensitive than overnight samples in identifying patients with incipient diabetic nephropathy.

(Arch Intern Med. 1990;150:373-375)