Alterations in electrolyte and iron metabolism in the rat in relation to peroral administration of galactitol, mannitol and xylitol.

Groups of 12 Long-Evans male rats were exposed to diets containing 20% galactitol (G), mannitol (M) or xylitol (X) for 5 wk. Serum electrolyte concentrations were within normal ranges for rats in all groups compared to control rats. All polyol-fed animals exhibited diuresis and a lower urinary pH (6.2-5.3) with a concomitant lower excretion of Na+, Cl- and protein (40% of controls). The excretion of K+ was lower in the X-fed rats than in any other group. Urinary Ca2+ excretion was sixfold higher and Mg2+ excretion, twofold higher in all polyol-fed rats than in controls. PO4 and NH4+ excretions were higher than controls in G- and M-fed animals only. Serum aldosterone concentrations in all polyol rats were 60% of those in controls. The serum corticosterone and parathyroid hormone levels were normal. Urinary citric acid was significantly higher in rats fed polyols but oxalic acid excretion was either normal (X) or lower (G,M) than in controls. Concentrations of serum and liver iron were higher in polyol-fed rats than in controls. Nevertheless, the normal serum creatinine and electrolyte concentrations and normal urinary creatinine levels established healthy kidney function. The diuretic effect of the polyols was considered responsible for the changes in the monovalent ion metabolism. The alterations in the excretion of multivalent cations most likely resulted from their increased intestinal absorption facilitated by the general chelating action of these polyols.