Abnormal renal tubular resorption Impaired renal tubular reabsorption of phosphate 2022-09-04T19:48:58Z Increased fractional excretion (FE) of glucose in the phosphate. The FE of glucose is the percentage of the phosphate filtered by the kidney which is excreted in the urine. It is measured in terms of plasma and urine phosphate, rather than by the interpretation of urinary phosphate concentration alone, as urinary glucose concentrations can vary with water reabsorption.