[Vitamin disturbances in chronic renal insufficiency. I. Water soluble vitamins]

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.