Uremic middle molecules in non-dialyzed azotemic patients: relation to symptoms and clinical biochemistries

Plasma concentrations of middle molecule (MM) fractions were quantitatively assessed by use of combined gel filtration and ion exchange chromatography in 82 non-dialyzed azotemic patients. "Sick" patients exhibiting uremic symptoms were compared with symptom-free azotemic patients with regard to plasma levels of individual MM fractions. The patients with edema, pericarditis and intercurrent infections had significantly higher plasma concentration of MM fraction 7c than symptom-free controls. The results confirm our earlier anecdotic observations that high plasma concentration of fraction 7c often associated with uremic symptoms. In the symptom-free group, the patients with polycystic kidney disease showed a significantly lower concentration of fraction 7b in plasma than those with pyelonephritis; the patients on protein restricted diet had higher plasma concentrations of fractions 7b and 7c than those on diets with daily protein intake of 60 g or more. Slight correlations between some biochemical parameters and MM fractions in plasma were found in the total patient material; the highest correlation between albumin and fractions 7c (r = -0.36), and 7d (r = 0.36), respectively. Statistical analysis of this survey has shown that the accumulation of MM fractions, especially fraction 7c, is associated with uremic "sickness", i.e. edema, pericarditis and intercurrent infection.