Aminohippuric acid or ''para''-aminohippuric acid (PAH), a derivative of

hippuric acid Hippuric acid (Greek language, Gr. ''hippos'', horse, ''ouron'', urine) is a carboxylic acid and organic compound. It is found in urine and is formed from the combination of benzoic acid and glycine. Levels of hippuric acid rise with the consumpt ...

, is a diagnostic agent useful in medical tests involving the

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

used in the measurement of renal plasma flow. It is an

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen at ...

derivative of the

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (G ...

and ''para''-aminobenzoic acid that is not naturally found in humans; it needs to be IV infused before diagnostic use.

Uses

Diagnostics

PAH is useful for the measurement of renal plasma flow. The renal extraction ratio of PAH in a normal individual is approximately 0.92. This means that unlike

inulin Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a ...

and

creatinine Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass). Biological relevance Serum creatinine (a blood measurement) is an impor ...

, which are filtered in the glomerulus and ignored by the rest of the kidney, aminohippuric acid is both filtered and secreted, being almost entirely removed from the bloodstream in a normal kidney.

Pharmaceuticals

Aminohippuric acid is often used as the

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

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.

Other

p''K''_a = 3.83

References

{{renal physiology Alpha-Amino acids Amino acid derivatives 4-Aminophenyl compounds Benzamides Acetic acids

Uses

Diagnostics

Pharmaceuticals

Other

See also

References