Albuminuria

To the Editor: Stephen et al¹ have written a nice review of the implications of albuminuria. However, they are clearly incorrect when they state, “Most of the protein in the urine is albumin filtered from the plasma.”¹ First, as they later point out in the article, the normal upper limit of protein excretion is about 150 mg/day, and only about 20 mg/day is normally albumin. Therefore, most of the protein in normally found in urine is not albumin, but instead is mostly a variety of globulins. Tamm-Horsfall mucoprotein or uromodulin is usually the protein found in highest concentration in normal urine.