Improved separation and quantification of the "middle molecule" b4-2 in uremia.
The plasma of uremic patients usually contains high concentrations of the so-called middle molecules (molecular mass, 300 to 1500 Da), which exert various toxic effects. Among these numerous substances, only one, named peak b4-2, has been correlated with uremic neuropathy. We describe our improvement of a two-stage chromatographic method, gel permeation followed by anion-exchange chromatography (J. Chromatogr. 146: 55-65, 1978), for separation and quantification of b4-2 in body fluids. In analyzing more than 300 samples from 43 uremic patients and 12 healthy subjects, we found a linear correlation between peak area at 254 nm and b4-2 concentration in the range 0.8 to 32 mg/L. The coefficient of variation, including data acquired during seven changes of columns, was 9%. Analysis time (80 min) was shorter than required with other methods. Our results confirm previous data for urinary b4-2 excretion by healthy subjects and for b4-2 removal rate in uremic patients undergoing hemodialysis or hemofiltration. Patients treated with continuous ambulatory peritoneal dialysis have a higher b4-2 excretion than do healthy subjects, suggesting a higher production of this solute in uremic patients.
D000553:Ambulatory Care; D001202:Ascitic Fluid / Q000032:analysis; D002852:Chromatography, Ion Exchange; D006801:Humans; D008970:Molecular Weight; D010530:Peritoneal Dialysis; D014118:Toxins, Biological / Q000302:isolation & purification*; D014511:Uremia / Q000378:metabolism*
D014118:Toxins, Biological; C026865:uremia middle molecule toxins