Emerging evidence shows that vitamin D is not only important for bone integrity but also has immunomodulatory properties. The lowest quartile of 25-hydroxyvitamin D (25-OHD) levels (<45 nmol/l) is independently associated with all-cause mortality in the general population(Reference Melamed, Michos and Post1). Patients with intestinal failure (IF) requiring long-term parenteral nutrition (PN) are susceptible to hypovitaminosis D as a result of inadequate absorption, suboptimal vitamin D dietary intake, advanced age, lack of exposure to UVB light and medication influencing vitamin D metabolism. In our institution Cernevit® is added to the PN as required.
We aimed to establish the prevalence of hypovitaminosis D in our tertiary long-term PN patient population. Patients were identified using the St. Mark's IF database. Retrospective data of 25-OHD levels, patient demographics, IF aetiology, month of blood test and vitamin D supplementation prescription were obtained. Cernevit® provided low-dose (<400 IU/d) supplementation and intramuscular (IM) injection of 150000 IU vitamin D every 3 months provided a higher dose. Total 25-OHD is defined as severely deficient (<25 nmol/l), deficient (25–50 nmol/l), insufficient (50–75 nmol/l) and adequate (>75 nmol/l).
One-hundred-and-ninety-nine PN patients were identified (134 female, median age was 53). The mean duration of PN was 70 months. The mean 25-OHD level was 61.6±36.5 nmol/l. Vitamin D levels were independent of age (P=0.37), sex (P=0.52) and IF aetiology (P=0.13). Vitamin D levels were higher in summer (June–November, 71.3±40.8 nmol/l) compared to the winter period (December–May, 54.7±31.6 nmol/l) (P=0.0015). One-hundred-and-forty-three (71.9%) patients had vitamin D levels below 75 nmol/l; 26.6% were insufficient, 37.2% were deficient and 8% were severely deficient. One-hundred-and-sixty-two patients received low dose of vitamin D, 13 received high dose of vitamin D and 24 had no supplements. No significant differences were seen between low-dose and un-supplemented groups (P>0.05). High-dose supplementation significantly increased vitamin D levels (P<0.05) but the levels were still below the recommended level.
* P=0.0226 (comparing high- and low-supplement groups).
Hypovitaminosis D (<75 nmol/l) is common in patients on long-term PN. Gender, age and IF aetiology were not associated with vitamin D status, but a seasonal variation was seen. The current available intravenous vitamin preparations do not contain an adequate dose of vitamin D for patients on PN. IM supplementation improves vitamin D levels but doses higher than 150 000 IU every 3 months is required in this population.
