Excretion of urinary amino acids in children with postural proteinuria.

The urinary excretion of free amino acids was studied in urine specimens from 12 subjects with postural proteinuria in recumbent posture and after a period of upright lordotic posture. The lordotic posture produced an increased urinary excretion of total amino acid and 12 amino acids, particularly of taurine, glutamic acid, a-amino adipic acid, valine, leucine, ethanolamine and arginine. However, 90 min after the lordotic posture, all amino acids returned to the initial values. Although, many factors must be considered in the evaluation of the urinary excretion of amino acids, an increased urinary excretion of amino acids occurring after the lordotic posture may be the result of reabsorption disturbance of the renal tubules.