SAN DIEGO — Reduced bone mineral density is common in children with cystic fibrosis, and few have normal serum concentrations of vitamin D, based on the results of a multicenter, cross-sectional study of 100 children with cystic fibrosis.
“The most important factors influencing bone mineral density are glucocorticoid use, poor nutrition, hypogonadism, physical inactivity, and malabsorption of vitamin D, [but] the exact pathogenesis of low bone mineral density in patients with cystic fibrosis is still unclear,” said lead investigator Dr. Dorota Sands of the department of pediatrics at the Institute of Mother and Child, Warsaw, Poland.
The average age of the patients (51 boys and 49 girls) was 13 years, and all had severe pancreatic insufficiency and were compliant with vitamin supplementation. All patients completed a 3-day dietary questionnaire and underwent standard biochemical blood tests and bone mineral density (BMD) testing with dual-energy x-ray absorptiometry, Dr. Sands reported in a poster session at the annual meeting of the Society for Inherited Metabolic Disorders.
Results of the cross-sectional component of the study revealed that 55 patients had a BMD within the normal range and 45 had a z score of −1 or below. The mean body mass index (BMI) for the group was 17.5 kg/m
“Only 12% had a sufficient dietetic supply of vitamin D,” Dr. Sands added. “Dietetic supply of vitamin D was on a low level, providing on average only 37% of [the] Recommended Daily Allowance [RDA]; 55% of patients did not achieve [the] RDA for calcium intake.”
A longitudinal analysis was performed in the 45 study participants who had a z score of −1 or below. These patients received an intervention consisting of 0.25 mcg of vitamin D3 for 1 year. The mean age of this subgroup of patients was 15 years, their mean BMI was 17 kg/m