Vitamin D deficiency in preoperative bariatric surgery patients

Obese patients are at risk of hypovitaminosis D. This is particularly concerning for those considering bariatric surgery because of the risk of postoperative nutritional deficiency. We hypothesized that it is necessary to screen for vitamin D deficiency preoperatively and conducted a study to identify the patterns of vitamin D deficiency among prospective bariatric surgery patients.

A retrospective analysis of available preoperative laboratory values was conducted for all consecutive patients (n = 312) scheduled to undergo bariatric surgery from January 2004 to October 2006.

Of the 312 patients, 179 (57.4%) were deficient in vitamin D preoperatively (25-hydroxyvitamin D < or =20 ng/mL). The average body mass index was 52.3 kg/m2 and the average age was 42.4 years. Of the 139 black patients evaluated, 109 (78.4%) were vitamin D deficient; of the 156 white patients evaluated, 57 (36.5%) were vitamin D deficient; and of the 14 Hispanic patients evaluated, 11 (78.6%) were vitamin D deficient. We also evaluated serum red blood cell folate, vitamin B(12), and free retinol vitamin A levels preoperatively. Of the 312 patients, 39 (12.5%) were vitamin A deficient and 11 (3.5%) were vitamin B(12) deficient. No patient had a red blood cell folate deficiency. Patients with hypovitaminosis D were also checked for secondary hyperparathyroidism; 42 patients (23.5%) fit the criteria (parathyroid hormone levels >75 pg/mL). Many patients with low vitamin D levels were being considered for the duodenal switch procedure.

The results of our study have shown that prospective bariatric surgery patients, particularly candidates for highly malabsorptive procedures, should be screened for hypovitaminosis D preoperatively. Our findings also showed that blacks are particularly at risk of vitamin D deficiency.