[Efficacy and safety of two vitamin supplement regimens on homocysteine levels in hemodialysis patients. Prospective, randomized clinical trial].
High levels of homocysteine (tHcy) are frecuent in MHD patients, and recognized as a risk factor for cardiovascular events. Vitamin supplements have been shown to lower serum Hcys, although optimal dose and efficacy is not well defined. Moreover, methylenetetrahydrofolate reductase (MTHFR) gene polymorphism can modulate its prevalence and response to treatment.


OBJECTIVE
To evaluate efficacy and safety of two vitamin supplement regimens on Hcys serum levels over a 12 month period.


METHODS
We conducted a prospective, randomised, double-blind trial in 60 stable MHD patients (68 +/- 13 years, 48% male, 50% diabetics). Patients were randomly assigned to one of two treatment regimens: 1) daily renal multivitamin containing folate (FA), vitamin B6 and B12 (5 mg, 10 mg and 0.4 mg respectively) (N = 27); and 2) supraphysiological daily doses (15 mg, 100 mg and 1 mg) (N = 33). These regimens were continued throughout the study period. Hcys levels were compared with a control group from the general population (N = 276) matched for age and gender.


METHODS
demographic and clinical data, serum levels of Hcys, FA, B6, B12 at baseline and after 1, 3, 6 and 12 months of treatment; MTHFR gene polymorphism (PCRRT).


RESULTS
At baseline, global prevalence of hyperhomocysteinemia (tHcy > or = 15 micromol/L) was 100% in patients and 22% en controls. Hcys levels were significantly higher in patients versus controls (32.4 +/- 8.9 vs 12.9 +/- 6.8; P < 0.0001). Both regimens were equally effective in reducing Hcys levels. As a whole, Hcys levels were reduced by 23.6% (P < 0.001) after one month of treatment. The highest reduction was observed at the sixth month (28.3%, 32.4 +/- 8.9 vs 22.7 +/- 6.4, P < 0.001) and remained stable thereafter. However, only 12% of patients normalised their plasma levels after 12 months of therapy. The effect of treatment was not influenced by age, gender, diabetes, body weight or time on MHD. Reduction rate of tHcy levels was related to baseline tHcy level (r = 0.500, P < 0.001) and baseline FA levels (r = -0.332, P = 0.009). The MTHFR polimorfism did not significantly modified the effect of the treatment. No side effects were associated with either regimen.


CONCLUSIONS
Hyperhomocysteinemia is common in patients with conventional HD schedules and this is not related to vitamin deficiencies. Vitamin supplements significantly reduce Hcys levels in a sustained but suboptimal way. Supraphysiological doses did not improve the results. Further studies are requiered to demonstrate that this effect is associated with an improval in morbidity and mortality.
Sánchez Alvarez
J E
JE
Hospital Tamaragua, Tenerife.
Pérez Tamajón
L
L
Hernández
D
D
Alvarez González
A
A
Delgado
P
P
Lorenzo
V
V
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003928:Diabetic Nephropathies / Q000097:blood / Q000150:complications; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics / Q000517:prevention & control*; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications* / Q000628:therapy; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D008875:Middle Aged; D011446:Prospective Studies; D006435:Renal Dialysis; D016896:Treatment Outcome; D014805:Vitamin B 12 / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D025101:Vitamin B 6 / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use
D006710:Homocysteine; D025101:Vitamin B 6; D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D014805:Vitamin B 12