Renal albumin handling: a look at the dark side of the filter.

Renal albumin handling is of major interest because albuminuria is an important risk factor for reno-cardiovascular diseases. In this issue a challenging study attempts to shift the paradigm of very low fractional albumin filtration and degradation in proximal tubule cells. The conclusions are of great potential relevance but require urgent validation so that we gain a clearer view of the dark side of the glomerular filter.