ABSTRACT
BACKGROUND: Several cross-sectional studies have shown improvement in the growth of children with cystic fibrosis (CF) because of increased awareness of and more comprehensive care of their special nutritional needs. However, longitudinal data on the nutritional status of these children are rare. OBJECTIVE: The objective was to compare changes in growth, body composition, and nutritional status between children with and without CF. DESIGN: This was a prospective 3-y cohort study of 25 children aged 5-10 y with CF, mild pulmonary disease, and pancreatic insufficiency and of 26 healthy control children. Three methods were used to assess body composition: measurements of skinfold thickness, total body water by deuterium oxide, and total-body electrical conductivity. Growth and body-composition changes over time were analyzed by a longitudinal mixed-effects model. RESULTS: Over the 3 y of the study, the statural growth of the boys with CF was slower than that of the control subjects (P = 0.004). The same divergence over time between the boys with and without CF was observed for fat-free mass assessed by skinfold-thickness measurements and total body water (P = 0.008 and 0.02, respectively) and for fat mass assessed by skinfold-thickness measurements and total-body electrical conductivity (P = 0.009 and 0.001, respectively). The differences in the pattern of changes in growth and body composition were less striking for girls. CONCLUSIONS: Despite comprehensive care, the growth of boys with CF was impaired on the basis of height, fat-free mass, and fat mass, when observed longitudinally. Caution should be used when interpreting cross-sectional measurements because they often do not detect suboptimal growth.
Subject(s)
Body Composition , Child Nutritional Physiological Phenomena , Cystic Fibrosis/physiopathology , Growth , Nutritional Status , Body Water , Case-Control Studies , Child , Child, Preschool , Cohort Studies , Cross-Sectional Studies , Electric Impedance , Female , Humans , Longitudinal Studies , Male , Prospective Studies , Skinfold ThicknessABSTRACT
Recent cross-sectional studies of children with cystic fibrosis (CF) have shown an improvement in their growth with improved nutritional status, but there are only a few longitudinal studies in this population. A four-year prospective study was conducted in 25 children with CF and 26 controls, ages 5 to 10 years at baseline, to describe changes in body composition using three independent methods of assessment: skinfold thickness, total body water by deuterium dilution, and total body electrical conductivity (TOBEC). The statural growth of the boys with CF was slower than that of the control boys. Using different methods, the fat-free mass and fat-mass increases were shown to be slower in boys with CF than in controls. These differences were less significant in girls. Despite comprehensive care, the growth of boys with CF may still not be optimal, as observed longitudinally.
Subject(s)
Body Composition/physiology , Cystic Fibrosis/physiopathology , Body Weight , Child , Child, Preschool , Cohort Studies , Deuterium , Electric Conductivity , Female , Growth , Humans , Male , Prospective Studies , Radioisotope Dilution Technique , Reference Values , Skinfold ThicknessABSTRACT
Adrenocorticotropic hormone (ACTH) secretion from the anterior pituitary is predominantly regulated by corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) synthesized in neurons of the paraventricular nucleus (PVN) of the hypothalamus. Secretion of ACTH occurs in pulsatile bursts. To explore the relationship between hypothalamic control and the pulsatile pattern of ACTH secretion, we measured ACTH in 2 min blood samples over 4 h in rats with intact and lesioned PVN during hypovolemic-stress or control conditions and also measured median eminence (ME) levels of CRH, AVP, and oxytocin (OT). Mean plasma ACTH was highest in the sham lesioned-hypovolemic group, lowest in the sham lesioned-control group and intermediate in the two PVN-lesioned groups. CRH in the ME was negligible in the lesioned animals and correlated with OT and AVP. Pulsatile secretion was observed despite PVN ablation. Visual inspection of composite time series suggested different temporal patterns of ACTH secretion. Principal components analysis of the individual ACTH time series revealed three significant eigenvectors which correlated differentially with the three treatment groups. Neither lesioned group had the steep rise over 10 min seen in plasma ACTH in the non-lesioned groups. Delayed ACTH rise after 30-60 min occurred in all but the sham control group. Our data suggest that CRH is responsible for immediate secretion of ACTH in response to hypovolemic stress and that regulators from non-PVN sites may be responsible for more delayed secretion of ACTH in this setting. The persistence of ME AVP and OT levels in the face of > 90% reduction in ME CRH levels leaves open the question of a role for one or both of these peptides in the delayed ACTH response following stress onset and in the generation of pulsatile ACTH secretory bursts.
