Anabolic role of urea in renal failure

The amount of urea nitrogen released and the amount reincorporated into albumin has been measured in healthy and uremic individuals on both normal and low-protein diets. The albumin synthesis rate was measured simultaneously. Gut urea breakdown was only 50% higher in renal failure than in health, but the efficiency of utilization of the nitrogen thus released was increased more than 6-fold in renal failure and was higher on a low protein than on a normal protein diet. The lower the albumin synthetic rate, the greater was the efficiency of incorporation of urea nitrogen into albumin. The rate of urea nitrogen incorporation into albumin increased on average 14-fold in chronic renal failure. The absolute rate of utilization (84 mumole/hr) was, however, small and comprised on average only 2.4% of the nitrogen used in albumin synthesis. These findings suggest that although some urea derived nitrogen is incorporated into albumin, the amount is not nutritionally significant even under conditions of protein deprivation and high urea availability.