Serum 25-Hydroxyvitamin D Is a Predictor of Serum 1,25-Dihydroxyvitamin D in Overweight and Obese Patients,

Abstract

Recent research suggests that 1,25-dihydroxyvitamin D [1,25(OH)(2)D], a steroid hormone that regulates calcium homeostasis, may also play a role in the development and progression of cancer, multiple sclerosis, cardiovascular, and other diseases. Decreased serum 1,25(OH)(2)D concentrations are often observed in overweight and obese patients. However, little is known about the factors that may influence 1,25(OH)(2)D renal synthesis, because it is generally accepted that serum 1,25(OH)(2)D concentration is strictly regulated by parathyroid hormone and serum concentrations of calcium and phosphorus. In this study, the associations among serum 1,25(OH)(2)D, serum 25-hydroxyvitamin D [25(OH)D], and body composition were analyzed in 1779 patients with excess body weight registered in a Metabolic and Medical Lifestyle Management Clinic in Oslo, Norway. According to our results, serum 25(OH)D, adiposity, age, season of blood sampling, and gender directly influence serum 1,25(OH)(2)D (r = 0.33; P < 0.001), with serum 25(OH)D being the strongest predictor for serum 1,25(OH)(2)D. The 1,25(OH)(2)D concentrations were 25.4 pmol/L (95% Cl: 19.3-31.5; P < 0.001) lower in the lowest 25(OH)D quartile to compared with highest quartile. A seasonal variation was observed for both vitamin D metabolites. Thus, our results suggest that in patients with excess body weight, serum 1,25(OH)(2)D concentrations were associated with 25(OH)D and varied during the year. Therefore, it may also be valuable to measure both serum 25(OH)D and 1,25(OH)(2)D for the evaluation of vitamin D status in overweight and obese persons.

Association of obesity with vitamin D deficiency and the clinical implications

“…Although researchers have reported that serum vitamin D levels can be a good predictor of obesity the role of vitamin D in lowering body weight is yet to be established. [4][5][6][7][8][9][10][11] In a study done in the eastern province of Saudi Arabia, the researchers found that the overall prevalence of obesity was 43.8%, and the peak prevalence was in the age group 50-59 years. Obesity was found higher among women than men and significantly higher in housewives, and among the less educated than others.…”

25-Hydroxy Vitamin D, Adiponectin Levels and Cardiometabolic Risk Factors in a Sample of Obese Children

“…This result agreed with Walker et al, [6] in Italy. In contrast, some recent studies have suggested that 25(OH)D may play a role in the regulation of adiponectin [11,15]. Adiponectin was identified and confirmed to be significantly decreased in 25(OH)D deficient obese pediatric [16].…”

“…Obesity is usually correlated with the higher prevalence of hypovitaminosis or the lower circulating 25(OH) D level in both pediatric as well as adult populations [15]. Low vitamin D stores as determined by 25-hydroxy vitamin D [25(OH) D] levels; which is the most accurate way to measure how much vitamin D is in the body ( normal, insufficiency or deficiency); are associated with increased risk for cardiovascular and mortality, but the mechanisms for this are unclear [16].…”

Vitamin D and Obesity

“…Similarly, during the summer, 7.1% of African-American women in the lowest quartile of fat mass (QFM) reached 80 nmol/liter, and only 3.7% of those in the highest QFM achieved this level; however, 73% of Caucasian-American women in the lowest QFM reached 80 nmol/liter, and only 30.7% of those in the highest QFM achieved this level. In other reports, there were also marked seasonal variations in absolute serum 25OHD 3 levels and the prevalence of vitamin D deficiency in subjects with mild to extreme obesity [20][21]. Similarly, measurements of BMI and waist circumference were higher in the winter than during the summer [22].…”