Youths With IBD May Need Large Doses of Vitamin D

By Megan Brooks
NEW YORK (Reuters Health) Apr 17 - In children and adolescents with inflammatory bowel disease (IBD) and insufficient serum vitamin D levels, taking 2,000 IU of vitamin D3 every day for six weeks, or a 50,000-IU dose of vitamin D2 every week, were both more effective at raising serum 25OHD concentration than 2,000 IU/day of vitamin D2.
Dr. Helen Pappa from Children's Hospital Boston, who worked on the study, told Reuters Health: "This is the first study to compare efficacy of three widely used vitamin D repletion regimens in children with vitamin D insufficiency. Findings from the study suggest that large vitamin D doses are needed to treat vitamin D insufficiency in this population, and that body weight rather than absorption affects regimen success in this population."
Based on the results of this study, "doses of 2,000 IU of vitamin D2 per day for six weeks should not be used because they may be inadequate in treating vitamin D insufficiency in adolescents with IBD," she said.
Vitamin D insufficiency (25OHD <20 ng/mL) is common in children with IBD and its treatment has not been studied, Dr. Pappa and colleagues said in a report online March 28 in the Journal of Clinical Endocrinology and Metabolism.
They enrolled in their study 71 patients with Inflammatory Bowel Disease between 5 and 21 years old and serum 25OHD <20 ng/ml.
All participants took oral elemental calcium (1,200 mg for those aged 11 or older and 800 mg for those younger than age 11) plus one of three vitamin D regimens: 2,000 IU vitamin D2 daily (study arm A; control), 2,000 IU vitamin D3 daily (arm B) and 50,000 IU vitamin D2 once weekly (arm C).
Sixty-one subjects completed the trial and two withdrew due to adverse events. All regimens were well tolerated, the researchers say. Adverse events occurred in one third of subjects overall, with no differences between the three arms. Most common were nausea (n=6), increased thirst and loss of appetite (n=5 each) and pruritus (n=4),
After six weeks of treatment, the mean changes from baseline in serum 25OHD were 9.3, 16.4 and 25.4 ng/mL in arms A, B and C, respectively.
Arms B and C experienced statistically significantly greater mean changes than arm A (Bonferroni adjusted p=0.03 and p=0.0004, respectively). "Serum 25OHD concentration increased on average by 130% and 190% in arms B and C, respectively, compared with just 62% in arm A," the researchers report.
Both arms B and C were 95% successful in raising serum 25OHD levels above 20 ng/mL; however, 62% of subjects in arm B and 25% in arm C did achieve a serum 25OHD level above 32 ng/mL, the investigators report. They estimate that a cumulative dose of 400,000 IU of vitamin D2 or 220,000 IU of vitamin D3 "would be sufficient to achieve this level."
The researchers say further studies are needed to "define a specific target serum 25OHD concentration and the best regimen by which to achieve and maintain this in young patients with Inflammatory Bowel Disease."
They also found that subjects who failed treatment were heavier, which supports weight-adjusted vitamin D dosing.
No change in serum parathyroid hormone (PTH) concentration was observed in any of the treatment arms. The authors note that baseline PTH levels were lower than reference PTH values for healthy children of similar age in their geographic region.
"PTH response to treatment was blunted suggesting a relative hypoparathyroidism in this population," Dr. Pappa said. None of the study subjects experienced hypercalcemia, hyperphosphatemia, or serum 25OHD concentration above 68 ng/mL after treatment.