Vitamin D insufficiency in obese patients with severe mental illness taking olanzapine

The purpose of the study was to assess the vitamin D status of obese patients with severe mental illness (SMI) treated with olanzapine. Fifteen obese SMI patients treated with olanzapine were pair-matched with healthy obese subjects. Another 52 overweight and obese SMI patients volunteered to participate in the study (totaln=67) and were divided into three subgroups (group A=overweight, group B=obese, group C=severely obese). Anthropometric, body composition, blood glucose, lipids, 25(OH)D, intact parathyroid hormone, and calcium measurements were performed. No differences were found between healthy and SMI subjects in any of the dependent variables (p>0.05). The obese and severely obese patients demonstrated significantly lower levels of serum 25(OH)D concentration (p<0.01) compared with overweight. A significant inverse correlation was found between serum 25(OH)D concentration and all anthropometric parameters (p<0.05). The results indicate that obese SMI patients appear to be vitamin D deficient, similar to healthy obese subjects. The level of obesity seems to play a significant role in their vitamin D status: the greater the body fat of the patients the lower the serum 25(OH)D concentration. Thus, as in healthy individuals, an inverse association exists between the degree of adiposity and the serum 25(OH)D concentration in SMI patients.