Vitamin D in infants with cystic fibrosis diagnosed by newborn screening

Aims:   Screening enables early nutritional deficiencies to be detected in those with cystic fibrosis (CF). Although vitamin deficiency is considered unlikely in older subjects with normal vitamin E levels, few studies have determined vitamin D status at diagnosis and its relationship to other fat-soluble vitamins.
Methods:   We reviewed vitamin levels in infants diagnosed with CF by newborn screening over a 5-year period in Melbourne, Australia. Vitamin D levels were determined using the IDS gamma-B 25-OH Vitamin D radio-immunoassay (Immunodiagnostic Systems Limited, Boldon, UK). Vitamins A and E were evaluated by high-performance liquid chromatography. We assessed the association between vitamin D level and sex, month of birth, pancreatic status, and vitamin A and E levels.
Results:   Fifty-eight infants were diagnosed at a median age of 1 month (range: 0–3 months). Initial vitamin D levels were assessed between 0.2 and 3.5 months in 30 (vitamin D) and 45 (vitamins A and E) infants. The number of infants deficient with vitamins D, E and A were 11 (37%), 7 (16%) and 27 (60%), respectively. Vitamin D levels were unrelated to sex, vitamin A or E levels, month of birth or pancreatic status, whereas vitamin A and E levels were significantly lower in those who were pancreatic insufficient. With supplementation, vitamin D increased over time.
Conclusions:   Vitamin D deficiency is common in infants newly diagnosed with CF by newborn screening and is unrelated to pancreatic status or predicted low vitamin E levels. Vitamin D deficiency is less common over time following treatment.