Reduced tubular reabsorption of phosphate during post-operative glucose infusions in humans

It is well-known that serum phosphate concentration decreases considerably during post-operative glucose infusions. The purpose of this study was to elucidate whether the renal handling of phosphate could be responsible for this fall. Twelve patients were studied during glucose and saline infusions on the 2 first post-operative days. The maximal tubular capacity for reabsorption of phosphate per litre of glomerulus filtrate (TmP/GFR) was significantly reduced during glucose infusions in relation to saline infusions. The glucose induced fall in serum phosphate concentration was correlated to the change in TmP/GFR (r2 = 0.71). This study did not explain the reduced TmP/GFR during the glucose infusions, but a high correlation was found between TmP/GFR and the changes in plasma glucose concentration during the infusions (r = -0.91).