Urinary excretion of hippuric acid by man

¹ Department of Biochemistry, Medical College of Alabama; and Department of Chemistry, University of Alabama Center, Birmingham, Alabama

A simplified scheme for interpretation of urinary hippuric acid excretion data in terms of consecutive irreversible first-order processes is presented. The rate of excretion of endogenous hippuric, uric, and glucuronic acids is constant under the conditions of the experiments. The average value for the excretion constant K_E for exogenous hippuric acid has been determined to be 2.7 hr^–1 (0.0452 min^–1) for doses of sodium hippurate ranging from 1 to 4 mEq. The average K_s for synthesis of hippurate from benzoate is 10.5 hr^–1 (0.175 min^–1) for doses of sodium benzoate ranging from 1 to 4 mEq. Study of 17 patients with varying degrees of renal disease as confirmed by standard p-aminohippurate and inulin clearances indicates that the determination of K_E may be of value in the study of renal function, particularly where standard clearance techniques are not available. Preliminary data indicate that K_s may be useful in the study of the delay in synthesis of hippurate from benzoate that has been observed in some cases of liver pathology.