In the kidney, both anions, phosphate and sulfate, are almost freely filtered and afterwards reclaimed (reabsorbed) to a large extent from tubular fluid along the proximal tubules. Under normal dietary conditions, fractional excretion of these anions is approximately 10%. Reabsorption of both anions occurs along the proximal tubules by active, saturable, and regulated transepithelial processes. Most of the transporters involved in renal handling of phosphate and sulfate have been identified and their transport functions as well as their cellular localizations have been described in detail. The role of these transporters in the renal handling of phosphate and sulfate has been investigated by the use of several mice knock out models and also by analysis of several inherited human diseases. Numerous hormonal and nonhormonal factors, have been described that alter renal excretion of phosphate or sulfate by mechanisms that alter the abundance of known phosphate/sulfate transporters and consequently renal excretion. These mechanisms contribute to the homeostasis of the extracellular concentrations of phosphate and sulfate.
© 2014 American Physiological Society.