Quantitation of Proteinuria in Patients with IgA Nephropathy and Membranous Nephropathy in Early Morning and Spot Urine Specimens

S. Yano, MD, Third Department of Internal Medicine, Gunma University School of Medicine, 3-39-22 Showa-cho, Maebashi, Gunma 371 (Japan) 600 ^ > Dear Sir, IgA nephropathy (IgA-N) and membranous nephropathy (MN-N) are common forms of chronic glomerulonephritis whose management relies on evaluation of urinary protein. Such measurements are usually done in the outpatient clinic on spot urine specimens, as the protein/creatinine ratio is reportedly well correlated with that in 24-hour urine specimens [1, 2]. We previously investigated the effects of posture on urinary protein excretion in patients with various renal diseases [3]. Urine was collected after 60 min spent in the supine position, following the collection of urine after standing for 60 min. We found that the increase in urinary protein excretion in patients with MN-N after standing significantly exceeded that in patients with IgA-N. We questioned whether there may also be a difference in urinary protein excretion between routine ‘spot’ urine and ‘early morning’ urine as collected from patients with IgA-N and MN-N at outpatient clinics. Our objective was to evaluate the urinary excretion of protein, albumin, IgG, and transferrin in early morning and spot urine specimens in patients with IgA-N and MN-N. A total of 22 Japanese patients, 13 patients with IgA-N (10 males and 3 females, mean age 42.5 ± 13.5 years) and 9 patients with MN-N (4 males and 5 females, mean age 55.8 ± 7.8 years) were included in this study, in which the diagnosis was determined by renal biopsy. Any patient with a serum creatinine level of > 2.0 mg/dl was excluded from the study. Serum creatinine lev-