Medium-sized peptides in the blood of patients with uremia.

We have carried out high performance liquid chromatographic analysis of serum and ultrafiltrate of blood obtained from uremic patients and normal subjects to elucidate the presence of medium-sized peptides unique to uremia. Many fluorescamine-positive substances, excluding amino acids and guanidine compounds, were increased in uremic serum compared with normal serum. At the 0.5-1.0 pmol/ml serum level, several peaks were unique to uremia. The retention time, fluorescamine reactivity, molecular weight distribution and the result of enzymatic digestion revealed that these peaks are peptidic substances.