High prevalence of vitamin D insufficiency in a United Kingdom urban morbidly obese population: implications for testing and treatment

Background: Current recommendations suggest universal screening of vitamin D status before bariatric surgery to identify individuals at risk for postoperative deficiency. However little is known about the magnitude or severity of vitamin D insufficiency in the morbidly obese population awaiting bariatric surgery in the United Kingdom. The purpose of this prospective observational study was to assess the prevalence and determinants of vitamin D insufficiency in an urban multiethnic U.K. population awaiting bariatric surgery.

Methods: Consecutive patients attending a morbid obesity service were comprehensively assessed using a recognized obesity staging tool. Data collected included 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), corrected calcium (Ca(2+)), body mass index (BMI), and the presence and severity of obesity associated co-morbidities, including type 2 diabetes (T2 DM), cardiovascular disease (CVD), depression, obstructive sleep apnea (OSA), and functional limitation.

Results: Of the 118 patients assessed, 79% were female, and 21% were male, with BMI of 52.6 ± 9.4 kg/m(2) (mean ± standard deviation) and mean age of 44 ± 11 years. Twenty-four percent had T2 DM, 28% CVD, 31% OSA, and 21% depression. Vitamin D insufficiency was found in 90% of the population, with a median serum 25(OH)D of 8.8 ng/mL. Secondary hyperparathyroidism was present in 43% of those with vitamin D insufficiency. Risk was not influenced by ethnicity, age, or gender. However severe functional limitation was associated with lower vitamin D status.

Conclusion: Regardless of ethnicity, vitamin D insufficiency appears to be typical among this clinic population; therefore, routine vitamin D supplementation is suggested for all individuals awaiting bariatric surgery rather than testing vitamin D status in an attempt to identify high-risk individuals.