This study does not address the specificity of urinary CA-VI as a biomarker for kidney diseases. However, even if increased levels of CA-VI are present in the circulation of pigs due to salivary gland disorders for example, it is probably not filtered at the glomerular level. In contrast, distal straight tubule alterations are most likely associated with increased urinary CA-VI concentrations, since the enzyme may be released from damaged epithelial cells lining them. In diseased kidneys in which hyperplastic inflammation is also present, the loss of tubules is extreme, and thus CA-VI concentrations may actually decrease. While the present preliminary data suggest that urinary CA-VI represents a potential biomarker of injury sustained by epithelial cells in the distal straight renal tubules of pigs,additional studies are needed to evaluate its clinical utility and diagnostic performance.