Could plasma cystatin C be useful as a marker of hemodialysis low molecular weight proteins removal?
BACKGROUND
Plasma cystatin (pCyst) is a well-assessed tool for measuring renal function, and it could also play a part in hemodialysis adequacy.


METHODS
pCyst and other uremic toxins (urea, creatinine, parathyroid hormone, prolactin) were assessed before and after a dialysis session in 18 hemodialysis patients: 7 on bicarbonate hemodialysis (BHD) and 11 on mixed convective dialysis (MCD; 6 standard hemodiafiltration and 5 acetate-free biofiltration). Plasma levels and reduction ratios (RR) were then compared between the BHD and MCD groups.


RESULTS
The mean pre-dialysis pCyst level is nearly the same in both groups (5.3 +/- 0.8 vs. 5.7 +/- 1 mg/l, p = ns), although a substantial decrease occurs after MCD only (mean 2.4 +/- 1 vs. 6.2 +/- 2.2 mg/l after BHD, p = 0.002). The mean pCyst RR (PCRR) of 55.5% after MCD is poorly related to prolactin and urea RR, fairly comparable to parathyroid hormone RR and very close to creatinine RR (58.4%).


CONCLUSIONS
Only MCD removes pCyst, but the amount of removal is different for other low molecular weight proteins (prolactin and parathyroid hormone) and similar for creatinine, a classic 'little molecule'. In view of the discrepancy of these findings, the use of pCyst in hemodialysis still seems premature and needs further studies.
Campo
Andrea
A
Renal Care Unit, S. Lazzaro Hospital, Alba, Italy. andrea_campo@hotmail.com
Lanfranco
Giacomo
G
Gramaglia
Luciana
L
Goia
Franco
F
Cottino
Roberto
R
Giusto
Viglino
V
D000368:Aged; D001639:Bicarbonates; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010281:Parathyroid Hormone / Q000097:blood*; D011388:Prolactin / Q000097:blood*; D006435:Renal Dialysis / Q000379:methods; D014508:Urea / Q000097:blood*
D001639:Bicarbonates; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D010281:Parathyroid Hormone; D014508:Urea; D011388:Prolactin; D003404:Creatinine