Effect of Para-Aminohippurate on Mannitol Determinations by the Periodate-Iodide-Thiosulfate Method.

Abstract

The usual thiosulfate titration method for estimation of mannitol requires revision when mannitol and sodium p-aminohippurate (PAH) are used together in renal function studies because PAH will react as mannitol in this method. A false elevation of mannitol levels of from 0.25-0.30 mg. % is found for each mg. % of PAH present. In the usual patient, this will lower Tm by about 10%. By acetylation of PAH with acetic anhydride just before the KIO4 oxidation of mannitol is carried out, it is possible to avoid this source of error.