Serum vitamin D levels in children with cystic fibrosis

Abstract

Osteopenia is increasingly recognized in adults with cystic fibrosis (CF), and is potentially related to vitamin D deficiency in both adulthood and childhood. Vitamin D supplements are recommended and prescribed to all pancreatic‐insufficient patients. We aimed to ascertain whether vitamin D deficiency in children with CF was prevalent. 25‐hydroxyvitamin D (25‐OHD) was measured in 290 children attending a specialist pediatric CF clinic for annual assessment. 25‐OHD levels were compared with reference values and to other biochemical markers, lung function, and growth. Levels were also analyzed by pancreatic status and by the presence of CF‐related liver disease. Median 25‐OHD was 65 (range, 9–190) nmol/l. One percent had levels below 15 nmol/l, and 6% had levels less than 25 nmol/l. Levels were lower in adolescents (P < 0.001) and during the “winter” months (P < 0.001). No relationship was found with pancreatic status or liver disease. In conclusion, the majority of children had normal 25‐OHD levels. Interpretation is difficult due to a lack of knowledge of optimal levels of 25‐OHD required for healthy bone accretion. Lower levels in adolescents may be a precursor to low levels in adulthood, and did not seem to be simply related to poor compliance with supplementation. This may reflect normal physiology. Pediatr Pulmonol.