Affiliations: [a] Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| [b] Department of Pathology, University of Iowa, Iowa City, IA, USA
| [c] Department of Neurology, University of Iowa, Iowa City, IA, USA
| [d] Department of Pediatrics, University of Iowa, Iowa City, IA, USA
Correspondence to: Amal Shibli-Rahhal, 200 Hawkins Drive, Endocrinology Department Room 400 GH, Iowa City, IA 52242, USA. Tel.: +1 319 353 7812; Fax: +1 319 353 7850; E-mail: [email protected].
Abstract: Background:Expert guidelines recommend annual monitoring of 25-hydroxyvitamin D (25-OHD) and maintaining 25-OHD ≥30 ng/ml in patients with dystrophinopathies. Objective:We hypothesized that 25-OHD remains stable and requires less frequent monitoring in patients taking stable maintenance doses of vitamin D. Methods:We performed a retrospective cohort study, using the electronic health record to identify 26 patients with dystrophinopathies with a baseline 25-OHD ≥30 ng/mL and at least one additional 25-OHD measurement. These patients had received a stable dose of vitamin D for ≥3 months prior to their baseline 25-OHD measurement and throughout follow-up. The main outcome measured was the mean duration time the subjects spent with a 25-OHD ≥30 ng/mL. Results:Only 19% of patients dropped their 25-OHD to < 30 ng/ml, with a mean time to drop of 33 months and a median nadir 25-OHD of 28 ng/mL. Conclusions:These results suggest that measurement of 25-OHD every 2–2.5 years may be sufficient in patients with a baseline 25-OHD ≥30 ng/mL and who are on a stable maintenance dose of vitamin D. Other patients may require more frequent assessments.