科研之友
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摘要
Background: Vitamin D deficiency is common in patients with cystic fibrosis (CF), and guidelines recommend 25-hydroxyvitamin D (250HD) levels 30 ng/mL. This threshold was selected because serum parathyroid hormone (PTH) rises in healthy individuals when the 250HD level falls below 30 ng/mL. PTH levels > 50 pg/mL are associated with an increased risk of bone loss. However, the relationship between 250HD and PTH has not been studied in CF We sought to determine the appropriate goal 250HD level in patients with CF by identifying the level below which the risk of PTH > 50 pg/mL begins to increase.
Methods: Levels of 250HD and PTH in 216 individuals with CF were collected prospectively. Individuals with 250HD < 30 ng/mL were treated with vitamin D2, and levels were reevaluated.
Results: Mean 250HD level was 25.7 +/- 12.4 ng/mL, and mean PTH level was 46.7 +/- 25.9 pg/mL. In 63% of individuals, 250HD level was < 30 ng/mL, and in 38.0% it was <= 20 ng/mL. Low 250HD levels were significantly associated with elevated PTH levels, with a mean PTH of 53.1 +/- 29.8 pg/mL for 250HD level 0 to 19 ng/mL; 51.1 +/- 30.7 pg/mL for 250HD level 20 to 29 ng/mL; 38.4 +/- 16.4 pg/mL for 250HD level 30 to 39 ng/mL; and 37.2 +/- 16.4 pg/mL for 250HD level >= 40 ng/mL (P = .006). We assessed the sensitivity of different 250HD thresholds to identify individuals meeting the goal of a PTH level < 50 pg/mL to reduce the risk of bone loss. To obtain 90% sensitivity, a 250HD level >= 35 ng/mL was required. Strikingly, 23% of individuals with 250HD levels 30 to 34 ng/mL still had a PTH level > 50 pg/mL. This decreased to 14% for 250HD level >= 35 ng/mL.
Conclusions: Inadequate serum 250HD levels are common in adults with CF and are associated with elevated PTH levels. Aiming to maintain 25-OHD levels >= 35 ng/mL in individuals with CF decreases the risk of having a PTH level associated with secondary hyperparathyroidism and bone loss. CHEST 2011; 140(2):469-474
- 出版日期2011-8
