Low Serum Vitamin B₁₂ Levels in Chronic High-Flux Haemodialysis Patients

Abstract

The occurrence of vitamin B₁₂ (B₁₂) deficiency in chronic haemodialysis patients and the need for its supplementation in these patients are still matters of debate. We measured serial predialysis serum B₁₂ levels, at 3- to 6-month intervals, in 67 unselected patients on our high-flux haemodialysis programme. Over a 12-month period, there was a significant fall in serum B₁₂ from 497 ± 200 (SD) to 391 ± 131 ng/l (p < 0.001). 22 patients developed subnormal serum B₁₂ levels and were commenced on hydroxocobalamin supplements. We were unable to demonstrate B₁₂ clearance during dialysis using blood side studies. Measurement of B₁₂ in the dialysate showed that 0-4.5 μg B₁₂ was cleared per dialysis. Using these B₁₂ measurements, in vivo B₁₂ clearance was estimated at 9.1 ml/min. Dietary studies on 24 unselected patients showed borderline or low B₁₂ intake in 4 patients. Absorption studies by whole-body counting on 6 patients using ⁵⁷Co and ⁵⁸Co showed normal B₁₂ absorption. The same radioisotope studies demonstrated no B₁₂ adsorption to the dialyser membrane. This study demonstrates that low serum B₁₂ levels occur in high-flux haemodialysis patients and that losses during dialysis and dietary deficiency may be contributing factors.

Convection with conviction–online hemodiafiltration for all: Single center clinical observations

“…Firstly, too efficient or rapid changes in calcium and phosphate control could trigger worsening of secondary hyperparathyroidism with worsening of ectopic calcification. 12 The only vitamin blood level routinely measured in our group of patients was vitamin B12 which appeared to decrease after a year in a small group of patients whose dietary habits had not changed and who eventually required supplementation. 10 Secondly, HDF could lower water-soluble vitamin levels if dietary intake is not guaranteed especially in elderly patients or patients on vegetarian diets who could be at increased risk.…”

Cerebral vascular complication and hyperhomocysteinemia in a cystinotic uremic child

“…Homocysteine is typically found at 2-3 times the normal level, and is inversely correlated with glomerular filtration rate [6,16]. The causes of elevated homocysteine levels in CRF have not been proven, but may include dietary or other causes of folate and vitamin B 12 deficiency and loss of water-soluble vitamins during dialysis [21][22][23][24][25]. CRF also results in lipid abnormalities that are a well-documented vascular risk factor [26].…”

Haemodiafiltration: Current Status

“…While removal of many solutes may be beneficial, the removal of others may be detrimental. Serum levels of vitamin B 12 (1,355 daltons) decrease in high-flux dialysis and supplementation has been recommended [24]. Vitamin C is reduced by 45 ± 14% during HDF with 25–45% of this attributable to convective clearance.…”