Short-Term UVB Treatment or Intramuscular Cholecalciferol to Prevent Hypovitaminosis D After Gastric Bypass-a Randomized Clinical Trial.

Background: Gastric bypass is increasingly used worldwide to treat morbidly obese patients with good results. However, several studies have reported low levels of vitamin D in spite of supplementation. In this randomized clinical trial, we have evaluated two principally different interventions, short-term UVB treatment or a single cholecalciferol injection, to prevent hypovitaminosis D.

Methods: Seventy-three patients, randomly treated by UVB (n = 26) or injection (n = 20), and compared to controls (n = 27), were followed for 6 months. Both interventions, 12 treatments of whole-body narrowband UVB and an intramuscular injection of 600,000 IU cholecalciferol, were given in December, when natural sunlight is limited. Blood samples for 25-OH-vitamin D (25[OH]D), intact PTH, calcium, and albumin were obtained at baseline, after 1 and 3 months, and after 6 months for the intervention groups. 25[OH]D was analyzed using a HPLC method.

Results: At baseline, 77.2 % of the patients had 25[OH]D <75 nmol/L. At 3 months, both UVB and cholecalciferol injection resulted in significantly higher 25[OH]D levels than controls (71.6 and 77.9 vs. 48.6 nmol/L, p < 0.05). The levels remained rather constant at 6 months (69.0 and 76.7 nmol/L, respectively); however, only injection therapy resulted in improved levels compared to baseline (55.7 nmol/L, p < 0.001). No toxic effects, nor significant changes in PTH or albumin-adjusted calcium, were seen.

Conclusions: In this randomized trial, both interventions, UVB and cholecalciferol, given as an adjunct to oral supplementation in gastric bypass patients, increased the levels of 25[OH]D. Simplicity makes injection therapy suitable for maintaining vitamin D levels during the Nordic winter.