Vitamin D intake, serum 25-hydroxy vitamin D and pulmonary function in paediatric patients with cystic fibrosis: a longitudinal approach.

Pancreatic-insufficient children with cystic fibrosis (CF) receive age-group-specific vitamin D supplementation according to international CF nutritional guidelines. The potential advantageous immunomodulatory effect of serum 25-hydroxy vitamin D (25(OH)D) on pulmonary function (PF) is yet to be established and is complicated by CF-related vitamin D malabsorption. We aimed to assess whether current recommendations are optimal for preventing deficiencies and whether higher serum 25(OH)D levels have long-term beneficial effects on PF. We examined the longitudinal relationship between vitamin D intake, serum 25(OH)D and PF in 190 CF children during a 4-year follow-up period. We found a significant relationship between total vitamin D intake and serum 25(OH)D (ß = 0·02; 95 % CI 0·01, 0·03; P = 0·000). However, serum 25(OH)D decreased with increasing body weight (ß = -0·79; 95 % CI -1·28, -0·29; P = 0·002). Furthermore, we observed a significant relationship between serum 25(OH)D and forced expiratory volume in 1 s (ß = 0·056; 95 % CI 0·01, 0·102; P = 0·018) and forced vital capacity (ß = 0·045; 95 % CI 0·008, 0·082; P = 0·017). In the present large study sample, vitamin D intake is associated with serum 25(OH)D levels, and adequate serum 25(OH)D levels may contribute to the preservation of PF in children with CF. Furthermore, to maintain adequate levels of serum 25(OH)D, vitamin D supplementation should increase with increasing body weight. Adjustments of the international CF nutritional guidelines, in which vitamin D supplementation increases with increasing weight, should be considered.

Vitamin E intake, α-tocopherol levels and pulmonary function in children and adolescents with cystic fibrosis.

Pancreatic insufficiency cystic fibrosis (CF) patients receive vitamin E supplementation according to CF-specific recommendations in order to prevent deficiencies. It has been suggested that higher serum α-tocopherol levels could have protective effects on pulmonary function (PF) in patients with CF. Whether current recommendations are indeed optimal for preventing deficiency and whether vitamin E has therapeutic benefits are subjects of debate. Therefore, we studied vitamin E intake as well as the long-term effects of vitamin E intake, the coefficient of fat absorption (CFA) and IgG on α-tocopherol levels. We also examined the long-term effects of serum α-tocopherol and serum IgG on forced expiratory volume in 1 s expressed as percentage of predicted (FEV1% pred.) in paediatric CF patients during a 7-year follow-up period. We found that CF patients failed to meet the CF-specific vitamin E recommendations, but serum α-tocopherol below the 2·5th percentile was found in only twenty-three of the 1022 measurements (2 %). Furthermore, no clear effect of vitamin E intake or the CFA on serum α-tocopherol was found (both P≥ 0·103). FEV1% pred. was longitudinally inversely associated with age (P< 0·001) and serum IgG (P= 0·003), but it was not related to serum α-tocopherol levels. We concluded that in the present large sample of children and adolescents with CF, vitamin E intake was lower than recommended, but serum α-tocopherol deficiency was rare. We found no evidence that higher serum α-tocopherol levels had protective effects on PF. Adjustment of the recommendations to the real-life intake of these patients may be considered.

Pancreatic Enzyme Replacement Therapy and Coefficient of Fat Absorption in Children and Adolescents With Cystic Fibrosis.

OBJECTIVES: Pancreatic enzyme replacement therapy (PERT) is the proven therapy to substantially reduce fat malabsorption in patients with cystic fibrosis (CF). Few details of the daily practice regarding PERT and the resulting coefficient of fat absorption (CFA) are known. We therefore recorded the PERT and CFA in a large cohort of pancreatic insufficient pediatric patients with CF. METHODS: We retrospectively studied 1719 completed 3-day dietary food records, including the pancreatic enzyme intake registrations, and 1373 CFA assessments of 224 patients with CF, ages 0-17 years. The clinical characteristics, PERT, expressed as an intake of lipase unit (LU) per gram of fat per day and LU per kilogram per day, and the CFA were described for the group as a whole and separately for those on enteral tube feeding. Cross-sectional relationship between the CFA and the LU per gram of fat per day and LU per kilogram per day were determined for each year of age. We also addressed the effect of the interventions done in patients with CFA outcomes <85%. RESULTS: The LU per gram of fat per day was relatively stable throughout the age groups, whereas the LU per kilogram per day fell markedly with age. The median CFA in the age group 17 varied between 86% and 91%, however, with a CFA below 85% in 325 of 1373 (24%) of the measurements. No relationship was found between PERT and CFA. The patients with persistent CFA less than 85% had significant lower z scores weight for age and weight for height (P = 0.01) than those with CFA at least 85%. CONCLUSIONS: In this study population, no correlation between an enzyme dosage and the degree of fat malabsorption was found; however, a CFA below 85% was found in 24% of the measurements.

The relationship between body growth and pulmonary function in children with cystic fibrosis.

AIM: To measure the weight and height of children with cystic fibrosis (CF) from 2 to 10 years of age and to investigate the relationship between these parameters and forced expiratory volume in 1 sec (FEV1) beginning at 6 years of age. METHODS: Weight and height were expressed as z-scores for weight-for-age (WFA), height-for-age (HFA), height-adjusted-for-target-height (HFA/TH) and weight-for-height (WFH). The children were categorised as having a z-score ≥0, between 0 and -1, or <-1 based on z-scores at 2 years of age. The cross-sectional and longitudinal relationships between FEV1 and WFA, HFA, HFA/TH and WFH were determined and the predictive value of these parameters for FEV1. RESULTS: We enrolled 156 CF children. Their mean weight and height were below the average for the healthy population. Both WFA and WFH increased with age (primarily before the age of 6), while the reduction in HFA and HFA/TH persisted. Importantly, the yearly decline in FEV1 was significantly slowed [by 1.8 and 1.9% for each unit increase in WFA and WFH (p < 0.015)] in children who gained weight. CONCLUSION: CF patients aged 2 to 10 years have long-term impaired growth. Nevertheless, weight gain slowed the decline in FEV1 in these patients.

Height Assessment in the Dutch-Origin Pediatric Cystic Fibrosis Population.

BACKGROUND: Height evaluation is an integral part of cystic fibrosis (CF) care. Height is compared with reference values by converting it to height-for-age (HFA) z scores. However, HFA z scores do not adjust for genetic potential (ie, target height [TH]), which could result in an incorrect estimation of the height. MATERIALS AND METHODS: To evaluate the magnitude of this potential problem, we assessed the agreement between HFA and HFA-adjusted-for-TH (HFA/TH) z scores in 474 Dutch children with CF. RESULTS: In this study sample, HFA z scores were -0.07 (95% confidence interval, -0.02 to -0.12) lower than HFA/TH z scores. When HFA and HFA/TH z scores were subdivided into 4 categories (≥0, <0 and ≥-1, <-1 and ≥-2, and ≤-2), a moderate agreement was found. HFA z scores were classified lower than HFA/TH z scores in 21% of the measurements and higher in 15% of the measurements. CONCLUSION: In clinical routine, height evaluation based on HFA may result in underestimation or overestimation of height growth, which may induce inappropriate nutrition interventions.

Dietary intake and lipid profile in children and adolescents with cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) patients are advised to derive 35% of their daily energy intake from dietary fat. Whether this high fat intake is associated with dyslipidaemia is unknown. We described the lipid profile and dietary intake in paediatric patients with CF. METHODS: 110 fasting lipid concentrations of 110 Dutch patients with CF were studied, along with 86 measurements of dietary intake. For the total group and for boys and girls separately, the lipid profile and the dietary intake were investigated. The cross-sectional relationship between the lipid concentrations and dietary intake was determined. RESULTS: The mean dietary fat intake was ≥35% of the total energy intake, along with a considerable consumption of saturated fat. We found lower concentrations of cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol, and increased concentrations of triglyceride and triglyceride to high-density lipoprotein cholesterol ratios. Lipid concentrations were not associated with dietary fat intake. CONCLUSION: This study lacks variation in dietary fat intake to exclude an effect on lipid concentrations as the distribution of dietary fat intake remained constant at a high level. Elevated triglyceride concentrations and triglyceride to high-density lipoprotein cholesterol ratios suggest an increased risk of cardiovascular disease. Any negative consequences of a high dietary fat intake on the overall lipid profile later in life cannot be excluded.

Vitamin A intake and serum retinol levels in children and adolescents with cystic fibrosis.

BACKGROUND: Pancreatic insufficient cystic fibrosis (CF) patients receive vitamin A supplementation according to CF-specific recommendations to prevent deficiencies. Whether current recommendations are optimal for preventing both deficiency and toxicity is a subject of debate. We assessed the longitudinal relation between serum retinol levels and appropriate variables. METHODS: We studied vitamin A intake, and the long-term effects of vitamin A intake, coefficient of fat absorption (CFA) and immunoglobulin G (IgG) on serum retinol levels in 221 paediatrics CF patients during a seven-year follow up period. RESULTS: Total vitamin A intake, derived from 862 dietary assessments, exceeded the tolerable upper intake level in 30% of the assessments, mainly up to age six. Although CF patients failed to meet the CF-specific recommendations, serum retinol deficiency was found in only 17/862 (2%) of the measurements. Longitudinally, we observed no association to serum retinol levels for total vitamin A intake, CFA, gender or age but serum retinol levels were associated with serum IgG levels. Each g/L increase in serum IgG level would result in a 2.49% (95% CI -3.60 to -1.36%) reduction in serum retinol levels. CONCLUSION: In this large sample of children and adolescents with CF, serum retinol deficiency was rare despite lower than the CF-specific recommendations. However, the TUL was commonly exceeded. A reduction in CF-specific vitamin A supplementation recommendations should therefore be considered. Moreover, serum retinol levels were not associated with vitamin A intake, CFA, gender or age, although a decreased serum retinol was associated with an increased serum IgG.

Comparison of height for age and height for bone age with and without adjustment for target height in pediatric patients with CF.

BACKGROUND: Height is a strong prognostic factor in cystic fibrosis (CF) and is usually compared to reference values of healthy children by expressing height as a z-score height-for-age (HFA). However, HFA does not take into account a potential delay in bone age (BA) and the genetic potential of the child and could therefore result in misclassification of short stature. METHODS: In 169 children with CF height, BA and target height (TH) were assessed. HFA, height for bone age (HBA), HFA adjusted for target height (HFA/TH) and HBA adjusted for target height (HFA/TH) were determined and children were categorized according to these four methods. RESULTS: Mean z-scores of the four methods ranged from -0.1 ± 0.8 (HBA/TH) to -0.5 ± 1.0 (HFA). Prevalence of short stature (z-score <-2 SD) determined by HFA (8%, n=14) was higher than when HBA, HFA/TH (both 5%, n=8) and HBA/TH (1% n=1) were applied. CONCLUSION: The method used to classify height affects outcome on a group level and for individual patients. Target height and bone age are likely to have added value in the interpretation of height in patients with CF.