LITHIUM AS AN INDICATOR OF PROXIMAL SODIUM REABSORPTION

About 80 per cent of the filtered lithium is reabsorbed in the tubules; this is the same as the fraction of filtered sodium that is reabsorbed in the proximal tubules. Fractional lithium reabsorption and proximal fractional sodium reabsorption are increased and decreased by the same procedures. Lithium seems to be reabsorbed mainly or exclusively in the proximal tubules. Determination of the fractional lithium reabsorption is simple; it may be a useful tool for the study o proximal sodium reabsorption in intact animals and in patients. © 1969 Springer-Verlag.