Proteinuria increases in proportion to podocyte number per glomerular tuft and podocyte density decrease.

<p><b>Panel A:</b> Urine PCR shown on a linear scale in relation to podocyte density demonstrating that as podocyte density decreases below approximately 100 per 10⁶ um³ the level of proteinuria exponentially increases. <b>Panel B:</b> The same data as shown in Panel A except that proteinuria and podocyte density are shown on a log scale. The dotted box represents the mean±1SD for podocyte density and the upper limit of normal urine PCR at 0.18. Note that the log scale shows that proteinuria increases in proportion to reduction in podocyte density over a wide range. <b>Panel C:</b> Glepp1% area is an alternative way of measuring podocyte density also shows an exponential (log) relationship with proteinuria. <b>Panel D:</b> % podocyte depletion (calculated as a % of the normal age-matched mean level for each sample) shown in relation to log urine PCR demonstrating that at the upper limit of normal urine PCR (0.18) occurs when approximately 20% of podocytes have been lost. By the time the urine PCR has reached a value of 1 about 40% of podocytes have been lost. These data illustrate that low level proteinuria is a moderately early marker of podocyte depletion in ASC biopsies.