Changes in vitamin D after gastrectomy

We previously reported that the administration of 1alpha hydroxy vitamin D3 was effective for treating post-gastrectomy bone disorders. Accordingly, we performed the present study to obtain evidence supporting the effectiveness of 1alpha hydroxy vitamin D3 in post-gastrectomy patients.

The study involved 22 outpatients who had undergone gastrectomy for gastric cancer and had not been treated with 1alpha 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.

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.

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.