A 30% to 40% prevalence of vitamin D deficiency among Crohn disease patients highlights the importance of testing these patients for vitamin D levels, according to the results of a population-based study presented October 15, 2013, at the American College of Gastroenterology Scientific Session in San Diego.
Vitamin D plays an important role in the immune system, and previous studies have shown that mutations in the vitamin D receptor have been linked to an increased risk of Crohn disease. Studies have also shown that lower vitamin D levels pre–Crohn disease diagnosis predict higher incidence of Crohn disease. “Because of the increasing number of studies of vitamin D's correlation to Crohn disease incidence and activity, there has been increased awareness of vitamin D's association with Crohn disease and, therefore, more frequent testing,” lead author Raina Shivashankar, MD, of the Mayo Clinic in Rochester, Minn, told ConsultantLive.
“Patients with Crohn disease may have a low vitamin D level as a potential cause of the disease, and therefore need to be supplemented. Also, vitamin D is vital to bone health, and patients with Crohn disease are often on prednisone, which can be deleterious to bone health. It is important to test for vitamin D and replace as necessary to maintain optimal bone density.”
Dr Shivashankar and colleagues aimed to assess the frequency of vitamin D testing and deficiency in 313 patients with Crohn disease. A well-established linked diagnostic index was used to identify all county residents in whom Crohn disease was diagnosed between 1970 and 2004. Patients were followed longitudinally, using their medical records. “We recorded data on the number of 25-hydroxyvitamin D tests and associated values and dates of testing,” she said, noting that 1,25-dihydroxyvitamin D levels were excluded. The frequency of vitamin D testing was calculated per year.
The researchers found the frequency of vitamin D testing increased over time. Mild to moderate vitamin D deficiency was found in about one-third of patients; only 5 patients had severe deficiency. About two-thirds of patients had normal vitamin D levels.
The prevalence of abnormal vitamin D tests was 40% in 2005-2008, and 31% in 2009-2013. The cumulative probability of having an abnormal vitamin D test was 0% at 1 year, 2.2% at 5 years, and 13.8% at 10 years. Time period of testing was significantly associated with frequency of vitamin D testing, while age and gender were not.
In conclusion, Dr Shivashankar said that “vitamin D testing frequency has increased over time, and there is a moderate prevalence of vitamin D deficiency in this population-based cohort of Crohn disease. The prevalence of vitamin D deficiency among those tested has decreased over the years, which may be due to increased vitamin D testing and repletion.”
She noted that “primary care physicians should remain cognizant that vitamin D levels may need to be repleted in patients with Crohn disease and should remember to check levels (25-hydroxyvitamin D) in these patients.”
Citation: Raina Shivashankar MD, William Tremaine MD, William Harmsen MS, Alan Zinsmeister PhD, Edward Loftus MD. Frequency of vitamin D testing and deficiency in Crohn disease: a populiation-based study. Program No. P1651. ACG 2013 Annual Scientific Meeting Abstracts. San Diego: American College of Gastroenterology.