[Hyperhomocysteinemia in CAPD patients: peritoneal transport of total homocysteine at peritoneal equilibration test and daily elimination of total homocysteine].
Peritoneal equilibration tests (PET) were performed in patients on continuous ambulatory and automated peritoneal dialysis (CAPD, APD) to evaluate the peritoneal transport capabilities for total homocysteine (tHcy) and other amino acids. Forty-five patients (24 males, 21 females, 50.6 +/- 12.8 years old) maintained on PD for 43.4 +/- 30.3 months participated in the study. PET revealed a markedly lower dialysate to plasma (D/P) ratio of tHcy at 4 hours (0.148 +/- 0.047) than those of other amino acids. A significant positive correlation between the D/P ratio of tHcy and the D/P ratio of creatinine was found, as well as between the D/P ratio of tHcy and the D/P ratio of albumin. The most significant positive correlation was found between dialysate and plasma levels of tHcy at 4 hours. There was no difference in the D/P ratio of tHcy between patients with D/P ratios of creatinine higher than the sample median of 0.68 and with D/P ratios of creatinine below 0.68, while the D/P ratios of other amino acids except threonine in the former patients tended to be higher than those of the latter patients. The D/P ratio of tHcy in patients with serum levels of albumin higher than 4.0 g/dl was significantly higher than that in patients with a ratio less than the sample median of 3.9 g/dl, whereas there were no significant differences in the D/P ratios of other amino acids. These observations suggest that the dialysate level of tHcy is primarily affected by the plasma level of tHcy, and that protein-bound Hcy mainly regulates the D/P ratio of tHcy. Daily peritoneal elimination of tHcy in 20 PD patients was 40.6 +/- 28.4 micromol. A significant positive correlation between the elimination of tHcy and plasma level of tHcy was also found. Daily elimination of tHcy in 7 patients with APD tended to be lower than that in 13 patients with CAPD. These findings indicate that the daily peritoneal elimination of tHcy does not compensate for the daily amount of tHcy metabolized in normal kidney, and that other therapies, such as folic acid administration, are required to improve hyperhomocysteinemia in patients on PD.
Hirose
S
S
Fourth Department of Internal Medicine, Saitama Medical Center, Japan.
Kono
R
R
Mitarai
T
T
Isoda
K
K
Kim
S
S
Shimoyama
H
H
D000328:Adult; D001692:Biological Transport; D002940:Circadian Rhythm; D005260:Female; D006710:Homocysteine / Q000097:blood* / Q000378:metabolism; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D010537:Peritoneum / Q000378:metabolism*
D006710:Homocysteine