An Audit of Folate and Vitamin B12 Levels after switching to Renavit®

Introduction: Routine practice within the East and North Herts NHS Trust has been to supplement folate and vitamin B12 losses during high-flux dialysis with intramuscular hydroxocobalamin and oral folic acid tablets. Despite the lack of robust evidence, guidance acknowledges vitamin provision as a low cost, low risk practice, which has demonstrated a reduction in morbidity and mortality. In 2014, the Trust switched to a new licensed oralmultivitamin preparation,Renavit®, which contains vitamins at doses that closely match the European Best Practice Guidelines. Here we discuss the change in practice and its impact on serum folate and vitamin B12 levels.

Method: Serum vitamin B12 and folate levels for 96 patients were taken before switching to Renavit®. Prior to the switch, patients were prescribed oral folic acid 5mg daily andhydroxocobalamin 1mg intramuscularly six monthly. Serum vitamin B12 and folate levels were taken again 12 months postswitch to one Renavit®tablet daily to determine any changesto the levels.

Results:Of the original 96 patients selected,36 were lost to follow up due to missed follow up blood tests at 12 months, death, receiving a transplant, changing modality or moving out of the area.

The following table shows the results for the 60 patients followed up:

Blood test / Pre Renavit switch
Mean +/- SD / Post Renavit switch
Mean +/- SD / Comparison
Vitamin B12 / 681ng/L
+/- 419 / 512ng/L
+/- 250 / P<0.01 (paired T test)
Folate / 20.8ng/L
+/- 6.71 / 20.2
+/- 6.82 / P=0.25 (Mann-Whitney U test\0

The results show a statistically significant reduction in vitamin B12 levels. However, this was not clinically significant as only onepatient pre and post switch was subtherapeutic and this was not in the same patient. The overall reduction in folate levels was not statistically or clinically significant. Four patients were low before theswitch and four post switch, again these were different patients.

Discussion:The results show a successful change in practice without an increase in the number of subtherapeutic concentrations of folate or vitamin B12 after switching toRenavit®. The switch reduces the potential harm of intramuscular hydroxocobalamin injections causing a haematoma in the anticoagulated haemodialysis patient. The overall reduction in vitamin B12 levels, which was statistically but not clinically significant, is likely due to a reduced bioavailability of an oral preparation compared to intramuscular dosing. The individual with subtherapeutic levels had a bowel resection, resulting in reduced absorption of vitamin B12 and should continueon intramuscular vitamin B12. The reduction in serum folate was non-significant and partially due to folate levels pre and post switch reported at the maximum level of the assay, making changes in levels more difficult to detect.The co-efficient of variation of the test is very high at 17% and patients were not fasted, so a folate rich meal within three hours of the test could increase levels. Generally, the lower folate levels seenare likely to be the reduced content of folic acid inRenavit® (1mg), compared to the daily 5mg dose given prior to the switch. The four patients with low folate levels were non-concordant in three cases and the fourth patient was marginally low. This group of patients should continue on intramuscular vitamin B12 and oral folic acid supplementation, given on the dialysis unit to aid concordance.