Vit C Deficiency in MHD

NDT Advance Access originally published online on November 14, 2006
Nephrology Dialysis Transplantation 2007 22(2):328-331; doi:10.1093/ndt/gfl534

Vitamin C deficiency in dialysis patients—are we perceiving the tip of an iceberg?

Garry J. Handelman

University of Massachusetts, Lowell, MA 01854 and Renal Research Institute, New York, NY 10128, USA

Correspondence and offprint requests to: Garry J. Handelman, 3 Solomont Way, University of Massachusetts, Lowell, MA, 01854, USA. Email: garry_handelman@uml.edu

The occurrence of vitamin C deficiency has complicated the management of dialysis patients since the beginning of renal replacement therapy .
The major portion of dietary vitamin C is provided by potassium-rich foods such as orange juice, strawberries and broccoli, but these foods are restricted for haemodialysis (HD) patients .

Under these circumstances, low dietary vitamin C intake can readily occur.

Since vitamin C is partly metabolized to oxalate, which can accumulate in renal failure patients, many clinicians only recommend a dose of 60–100 mg/day, which may not be optimal.
The problem is made more severe by vitamin C losses during dialysis, which may remove several hundred mg of vitamin C in a single dialysis treatment .

Plasma vitamin C in dialysis patients is frequently <10> population. Normal plasma vitamin C levels in the non-dialysis population are 30–60 µM

Very high levels of vitamin C can also occur in dialysis patients, the effect of dialysis on vitamin C is highly variable. For patients who take large vitamin C supplements, the lack of the normal renal clearance mechanism can result in very high plasma levels (>200 µM)

Vitamin C deficiency can interfere with iron absorption and utilization, as well as leading to various abnormalities that are part of the syndrome of scurvy.

There is a situation where a large portion (10–25%) of dialysis patients have plasma vitamin C levels <10> plasma vitamin C <2> Epidemiological data suggest that these low plasma vitamin C levels are associated with increased mortality .

Although a 60–100 mg daily vitamin C supplement is generally recommended, prescriptions are provided only to 10–70% of patients, depending on nationality . Lack of compliance may lead to even lower levels of actual vitamin C usage.

The instability of vitamin C leads to problems in laboratory analysis , and vitamin C is not routinely measured in dialysis practice.

Concerns about oxalosis need to be vigorously addressed, but if vitamin C is demonstrated to be safe, its more active use could lead to reduction of iron burden, more efficient erythropoiesis and alleviation of some of the scorbutic symptoms seen in HD patients.