Superiority of a high loading dose of cholecalciferol to correct hypovitaminosis d in patients with inflammatory/autoimmune rheumatic diseases.

OBJECTIVE: To compare 3 different cholecalciferol supplementation regimens in patients with rheumatic diseases.
METHODS: One hundred fifty-four patients who completed a 6-month course of cholecalciferol supplementation, of whom 111 had an autoimmune/inflammatory rheumatic disease (ARD) and 43 osteoarthritis (NARD), were retrospectively identified from a database of 872 consecutive adult patients who attended a tertiary level immuno-rheumatology clinic from 2007 to 2010. Patients with renal failure or primary hyperparathyroidism were excluded. Plasma 25-hydroxy vitamin D [25(OH)D] and parathyroid hormone (PTH) concentrations were evaluated at baseline and after completion of treatment with (i) a single oral dose of cholecalciferol 300,000 IU, followed by oral cholecalciferol 800-1000 IU daily for 6 months [high-dose loading treatment (HLT) group; n = 40]; (ii) a single oral dose of cholecalciferol 100,000 IU, followed by daily oral cholecalciferol as above [low-dose loading treatment (LLT) group; n = 30]; or (iii) daily oral cholecalciferol as above but without the loading dose [standard therapy (ST); n = 84].
RESULTS: The rates of serum 25(OH)D and PTH normalization (defined as values > 75 nmol/l and < 72.9 pg/ml, respectively) were as follows: HLT, 52.5% (95% CI 37.5-68.5) and 69.2% (95% CI 54.7-83.3); LLT, 36.7% (95% CI 19.7-54.3) and 53.8% (95% CI 36.2-71.8); ST, 31.0% (95% CI 21.1-40.9) and 35.0% (95% CI 14.1-55.9). All regimes increased 25(OH)D (p < 0.001) but only HLT reduced PTH (p < 0.01) in comparison to baseline. The ARD group had a similar 25(OH)D increase but a smaller PTH reduction than the NARD (p < 0.05).
CONCLUSION: An HLT cholecalciferol regimen is needed to correct hypovitaminosis D of patients with rheumatic diseases, with superior 25(OH)D normalization and PTH suppression rates at 6 months.