Deficiency and/or altered metabolism of
vitamins in CRI is caused by
uremic toxins,
dietary restrictions, catabolic illness, losses during dialysis and drug interaction. There are no reports of consistent studies on
vitamin status of water soluble
vitamins in CRI.
Vitamin B1 (
thiamine) deficiency several authors found most frequently in
CAPD patients. The cause of this deficiency depends probably on increased requirement of
vitamin B1 due to high
glucose intake with
peritoneal dialysis solution. In patients with
polyneuropathy high doses of
thiamine pyrophosphate (
Cocarboxylase), given i.v., can be helpful in this respect. There are conflicting reports concerning plasma level of
vitamin B2 (
riboflavin) in CRI patients. Some authors recommend its supplementation. The majority of patients with CRI exhibit biochemical and clinical signs of
vitamin B6 deficiency. There exists an univocal opinion that supplementation of this
vitamin effects the cellular immune system and the
amino acid metabolism as well. An adequate dose of
vitamin B6 is still a matter of dispute. Evidence of
vitamin B12 deficiency has been reported rarely, thus, only few authors recommend the supplementation of it, mainly in
CAPD patients. According to most authors the losses of
folic acid and
ascorbic acid during dialysis require oral supplementation. Despite the divergences in opinions concerning the deficiency of water-soluble
vitamins in CRI patients, the supplementation of these
vitamins is practised in many nephrological centers. The amount and the route of
vitamins, administered to CRI patients, should be individualized.