Changes in vitamin D after gastrectomy

Background. We previously reported that the administration of 1 alpha hydroxy vitamin D3 was effective for treating post-gastrectomy bone disorders. Accordingly, we performed the present study to obtain evidence supporting the effectiveness of 1 alpha hydroxy vitamin D3 in post-gastrectomy patients. Methods. The study involved 22 outpatients who had undergone gastrectomy for gastric cancer and had not been treated with 1 alpha hydroxy vitamin D3 or calcium. They comprised 17 men and 5 women, with a mean age of 61.9 years. Laboratory tests were performed to examine the following parameters: 1,25(OH)(2) vitamin D3; 25(OH) vitamin D3; 24,25(OH)(2) vitamin D3; ionized calcium; calcium; phosphorus; alkaline phosphatase; N-parathyroid hormone; and osteocalcin. Results. The level of 1,25(OH)(2) vitamin D3, the most active of the vitamin D metabolites, was found to be normal in all of the patients. In contrast, the level of 25(OH) vitamin D3, which shows weak activity, was below the normal range in 7 of the 22 patients (31.8%). The mean serum level of 25( OH) vitamin D3 was significantly lower in patients at 1 year or more postoperatively than the level in those at less than 1 year postoperatively (P = 0.041), as well as being significantly lower in patients who had received total gastrectomy than in patients who underwent other gastrectomy procedures. The level of 24,25(OH)(2) vitamin D3, a metabolite of 25(OH) vitamin D3 that shows weak activity, was below the normal range in 19 of the 22 patients (86.4%). On multivariate analyses, factors associated with the change in vitamin D metabolites did not remain. Conclusion. The patients showed a decrease of 25(OH) vitamin D3 and 24,25(OH)(2) vitamin D3, which are metabolites that show weak activity. This suggests that a homeostatic response maintains the normal level of 1,25(OH)(2) vitamin D3, which is important for calcium regulation. Thus, it was suggested that gastrectomy had a moderate influence on the metabolism of vitamin D. However we could not detect any factor associated with the decrease of 25(OH) vitamin D3 and 24,25(OH)(2) vitamin D3.