|Other names||PAH, PAHA, Aminohippurate, 4-Aminohippuric acid , N-(4-Aminobenzoyl)glycine, para-Aminohippurate|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||194.19 g/mol g·mol−1|
|3D model (JSmol)|
Aminohippuric acid or para-aminohippuric acid (PAH), a derivative of hippuric acid, is a diagnostic agent useful in medical tests involving the kidney used in the measurement of renal plasma flow. It is an amide derivative of the amino acid glycine and para-aminobenzoic acid that is not naturally found in humans; it needs to be IV infused before diagnostic use.
PAH is useful for the measurement of renal plasma flow.
Aminohippuric acid is often used as the sodium salt sodium para-aminohippurate. During World War II, para-aminohippurate was given along with penicillin in order to prolong the time penicillin circulated in the blood. Because both penicillin and para-aminohippurate compete for the same transporter in the kidney, administering para-aminohippurate with penicillin decreased the clearance of penicillin from the body by the kidney, providing better antibacterial therapy. Transporters found in the kidney eliminate organic anions and cations from the blood by moving substances, in this case, drug metabolites, from blood into urine. 
pKa = 3.83
- Costanzo, Linda. Physiology, 4th Edition. Philadelphia: Lippincott Williams and Wilkins, 2007. Page 156-160.
- Reubi, François C. (1953-04-29). "Glomerular filtration rate, renal blood flow and blood viscosity during and after diabetic coma". Circ. Res. 1 (5): 410–3. doi:10.1161/01.res.1.5.410. ISSN 0009-7330. PMID 13082682. Retrieved 2008-03-19.
- Beyer, Karl H.; Flippin, Harrison; Verwey, W. F.; Woodward, Roland (1944-12-16). "THE EFFECT OF PARA-AMINOHIPPURIC ACID ON PLASMA CONCENTRATION OF PENICILLIN IN MAN". Journal of the American Medical Association. 126 (16): 1007–1009. doi:10.1001/jama.1944.02850510015003. ISSN 0002-9955.