Cystathionine is more readily cleared from the plasma than other amino acids. This is because the amino acid has a very low tubular maximum (Tm), in the order of 1 μmole per minute per 1.73 square meters body surface area (BSA). No essential differences in the reabsorption of cystathionine were observed in four normal subjects, two patients with homozygous cystathioninuria, one patient with heterozygous cystathioninuria, and one patient with cystinuria.
