Chronic Undernutrition/Growth Retardation in Cystic Fibrosis

Trends in Growth and Maturation in Children with Cystic Fibrosis Throughout Nine Decades

Since cystic fibrosis (CF) was first described in 1938, there have been many discoveries and innovations in the field, each having a profound impact on survival, growth and quality of life. For example, the introduction of enteric-coated pancreatic enzyme microspheres increased fat absorption and improved nutritional status. Early detection of CF through newborn screening facilitated prompt nutritional intervention for infants at high risk of malnutrition. Use of anti-pseudomonal therapy, such as inhaled tobramycin, increased weight gain and pulmonary function in addition to reducing pulmonary exacerbations. Similarly, DNAse and hypertonic saline improved pulmonary function and reduced exacerbations. The identification of the CFTR gene and its protein product were fundamental in understanding the pathophysiology of CF and paved the way for advances in both diagnosis and management. In fact, CFTR modulator therapies have revolutionized the care for individuals with CF. Here, we examine the impact of these interventions on the nutritional status, growth and pubertal maturation of children and adolescents with CF.

Cystic fibrosis: myths. mistakes, and dogma

As a student I recall being told that half of what we would learn in medical school would be proven to be wrong. The challenges were to identify the incorrect half and, often more challenging, be willing to give up our entrenched ideas. Myths have been defined as traditional concepts or practice with no basis in fact. A misunderstanding is a mistaken approach or incomplete knowledge that can be resolved with better evidence, while firmly established misunderstandings can become dogma; a point of view put forth as authoritative without basis in fact. In this paper, I explore a number of myths, mistakes, and dogma related to cystic fibrosis disease and care. Many of these are myths that have long been vanquished and even forgotten, while others are controversial. In the future, many things taken as either fact or "clinical experience" today will be proven wrong. Let us examine these myths with an open mind and willingness to change our beliefs when justified.

Nutritional care in children with cystic fibrosis: are our patients becoming better?

Over the last 30 years, major advances have occurred in our understanding of the disorder cystic fibrosis (CF) with the discoveries of the underlying chloride transport defect and the 'CF gene', the CF transmembrane conductance regulator gene. Equally important from a clinical and patient perspective are the improvements in median survival from less than 10 to 20 years prior to 1980, approaching 30 years during the 1980s and over 45 years more recently. Improved antibiotic regimens and lung clearance therapy contributed to the enhanced survival, but a key factor accredited as adding a further 10 years to the median survival was improving and then maintaining normal growth and nutrition. In the main, the latter were achieved by adherence to a 'high-fat high-energy' diet rather than the advocated virtually universal policy of the 'low fat', which was associated with wasting and linear growth failure. The high-fat diet in conjunction with better control of malabsorption due to microspheric pancreatic enzyme replacement therapy, attention to adequate fat-soluble vitamin supplementation and newborn screening has ensured that at least 80-90% of children with CF will achieve better health and survival through their adult years.

Plasma insulin-like growth factor-I determinations in patients with cystic fibrosis: Influence of the nutritional and liver status

Insulin-like growth factor-1 (Igf1), a useful and early marker of undernutrition in inflammatory diseases, is dependent on the calorie and protein content of the diet. In 31 children and adolescents with cystic fibrosis (CF), a chronic inflammatory disease, the influence of the degree of liver dysfunction and the protein and calorie content of the diet on the circulating Igf1 was evaluated. No significant difference in the median plasma Igf1 concentration, measured by RIA, between the CF children (0.80 U/ml) and a for age and puberty matched control group (0.61 U/ml) was found. Expressing the Igf1 concentration as a percentage of normal for age, gave for the CF patients with liver involvement a lower level (median: 76%) than in those without (median: 101%). No correlation existed between the circulating Igf1 levels and the body height SDS, the body weight index and the calorie or protein intake of the patients.

Cystic fibrosis growth retardation is not correlated with loss of Cftr in the intestinal epithelium

Maldigestion due to exocrine pancreatic insufficiency leads to intestinal malabsorption and consequent malnutrition, a mechanism proposed to cause growth retardation associated with cystic fibrosis (CF). However, although enzyme replacement therapy combined with increased caloric intake improves weight gain, the effect on stature is not significant, suggesting that growth retardation has a more complex etiology. Mouse models of CF support this, since these animals do not experience exocrine pancreatic insufficiency yet are growth impaired. Cftr absence from the intestinal epithelium has been suggested as a primary source of growth retardation in CF mice, a concept we directly tested by generating mouse models with Cftr selectively inactivated or restored in intestinal epithelium. The relationship between growth and functional characteristics of the intestines, including transepithelial electrophysiology, incidence of intestinal obstruction, and histopathology, were assessed. Absence of Cftr exclusively from intestinal epithelium resulted in loss of cAMP-stimulated short-circuit current, goblet cell hyperplasia, and occurrence of intestinal obstructions but only slight and transient impaired growth. In contrast, specifically restoring Cftr to the intestinal epithelium resulted in restoration of ion transport and completely protected against obstruction and histopathological anomalies, but growth was indistinguishable from CF mice. These results indicate that absence of Cftr in the intestinal epithelium is an important contributor to the intestinal obstruction phenotype in CF but does not correlate with the observed growth reduction in CF.

Body composition assessed by the 4-component model and association with lung function in 6-12-y-old children with cystic fibrosis

BACKGROUND

Malnutrition is an indicator of a poor prognosis in patients with cystic fibrosis (CF). Previous body-composition (BC) studies in children with CF used 2-component models (2CMs) to assess fat mass (FM) and fat-free mass (FFM), but to our knowledge no study has used the gold-standard 4-component model (4CM), which allows for a more accurate evaluation of the nature of both elements.

OBJECTIVE

We measured BC by using the 4CM in 6-12-y-old children with CF to 1) compare findings with those of healthy, matched control children and reference data; 2) relate BC to lung spirometry [forced expired volume in 1 s (FEV₁)]; and 3) compare findings with those from more commonly used 2CM techniques.

DESIGN

One hundred clinically stable children with CF (57% girls) aged 6-12 y were measured by using the 4CM. Children with CF underwent spirometry (FEV₁).

RESULTS

Girls with CF had significantly less FM than did healthy girls, even after adjustment for height and pubertal status; boys with CF had higher body mass index SD scores than did healthy boys. FM in girls was positively associated with the FEV₁ percentage predicted. The 2CM FM was significantly different from the 4CM FM, with differences dependent on sex and condition, although most techniques identified a relation between FM and FEV₁ in girls.

CONCLUSIONS

Although shorter than healthy children, boys with CF were heavier and had a BC within the normal range; however, girls with CF had lower FM than did healthy girls, and this was associated with poorer lung function. Given the worse prognosis in girls, this finding merits more attention. The reliability of 2CM techniques varied with sex and health status.

Evaluation of formulas for calculating total energy requirements of preadolescent children with cystic fibrosis

BACKGROUND

To support age-appropriate growth and to prevent and treat malnutrition in children with cystic fibrosis (CF), energy requirements for those children are often set above the requirements for healthy children. Care providers use one of several empirically derived formulas to calculate energy requirements, yet the validity of these formulas has seldom been tested.

OBJECTIVE

We evaluated 6 proposed formulas for calculating energy requirements in children with CF against a total energy requirement for children with CF (TER-CF) derived from measured total energy expenditure, fecal fat energy loss, and the theoretic energy required for age-appropriate tissue accretion.

DESIGN

Subjects were children aged 6-8 y who had CF and pancreatic insufficiency. Calculated TERs from each formula were evaluated against TER-CF by using summary statistics, regression analysis, and residual plots.

RESULTS

Subjects (n = 53) had suboptimal nutrition and growth status and mild-to-moderate lung disease. The formula that most closely (within 2%) approximated TER-CF was the estimated energy requirement (EER) formula at the active level (EERact). Regression analysis of TER-CF onto calculated TER from each formula yielded the best indexes of model fit for the EERact formula; residual plots of the EERact formula were tightly and normally distributed around zero.

CONCLUSIONS

The EERact formula should be used to establish TER-CF in children in this age group who have mild-to-moderate CF. Changes in weight, height, and other indicators of nutritional status must be monitored to modify TER-CF as needed to support individual patient care goals.

Resting energy expenditure in cystic fibrosis as an indicator of disease severity

BACKGROUND

An imbalance of energy expenditure has been reported in Cystic Fibrosis (CF). High-energy diets, in combination with pancreatic enzymes, do not always compensate for energy requirements. The aim of this study was to investigate the relation between Resting Energy Expenditure (REE) and disease severity in CF.

METHODS

REE was measured with indirect calorimetry in a group of 38 clinically stable CF patients (32 with pancreatic insufficiency and 6 with pancreatic sufficiency). Correlations between REE and pulmonary function as well as clinical status were studied.

RESULTS

Increased REE expressed as a percentage of predicted (REE%) was demonstrated in pancreatic insufficient CF patients (PI) (113.3+/-2.5%), as compared to pancreatic sufficient (98.9+/-2.5%) and healthy subjects. The elevated REE% in the PI group was not affected by gender and exhibited a strong correlation with the clinical status of the patients (r=-0.641).

CONCLUSIONS

Our data analysis supports the argument that the percentage of predicted REE is an objective indicator of disease severity and progression as well as energy requirements in the assessment of CF patients.

Differences in resting energy expenditure between male and female children with cystic fibrosis

OBJECTIVES

To evaluate which factors might contribute to raised resting energy expenditure (REE) in patients with cystic fibrosis (CF).

STUDY DESIGN

REE and anthropometry were measured in 134 (males = 68) children with CF and 100 (males = 51) controls (range, 3-18.7 years) in an outpatient setting. Bacterial colonization, liver disease, inhaled steroid use, pancreatic and pulmonary function, sex, and genotype were determined and regression analysis was used to determine the predictors of REE in the group with CF.

RESULTS

REE for children with CF was increased on average by 7.2% compared with controls. This increase was greater for females than for males. REE in males was positively associated with fat-free mass (FFM), pancreatic insufficiency (PI), and liver disease, and negatively associated with pulmonary function, whereas in females, REE was positively associated with FFM and PI. REE (adjusted for FFM) was higher in children with a severe mutation (5495 +/- 47 kJ) compared with a mild mutation (5,176 +/- 124 kJ, P <.02).

CONCLUSIONS

PI, severe mutations, and female sex are the main contributing factors to elevated REE in patients with CF with near normal pulmonary function.

Longitudinal investigation of energy expenditure in infants with cystic fibrosis

OBJECTIVE

To determine when energy expenditure becomes elevated in infants with cystic fibrosis (CF).

DESIGN

Longitudinal studies of total energy expenditure (TEE) using doubly labeled water were conducted in infants identified with CF by newborn screening through the first year of life.

SETTING

Hospital and community based studies in Denver, Colorado, USA and Cambridge, UK.

RESULTS

Eight of the 12 infants enrolled had begun enzyme therapy but were clinically asymptomatic. Four of the 12 infants were heterozygous for the delta F508 mutation, however no difference was seen in TEE from the remaining homozygous infants. TEE was compared to control cohorts at 2, 6 and 12 months of age. There was no difference from the control groups in TEE/kg fat free mass (FFM)/day at 2 months. However, by 6 months of age TEE/kg FFM/day in infants with CF exceeded that of age-matched controls by 25% (P<0.001). This elevation in TEE continued at 12 months of age exceeding that of controls by 30% (P<0.05).

CONCLUSIONS

These results indicate that infants with CF have increased energy needs by 6 months of age and that early diagnosis alone does not prevent the development of increased caloric requirements. These findings emphasize the need for close nutritional monitoring to prevent suboptimal growth during infancy in this population.

SPONSORSHIP

This research was supported by grant number 5 MO1 RR00069, General Clinical Research Centers Program, National Center for Research Resources, NIH.

Comparison of growth status of patients with cystic fibrosis between the United States and Canada

BACKGROUND

Differences in growth status of patients with cystic fibrosis (CF) between the United States and Canada were reported in the 1980s based on analysis of data from 2 regional CF centers.

OBJECTIVE

We evaluated the current growth status of the entire CF population in the United States and Canada in view of recent advances in the treatment of CF.

DESIGN

Growth data from the 1992-1994 CF Patient Registries were analyzed.

RESULTS

Mean height and weight were at approximately the 30th percentile for children with CF in the United States. Mean height and weight were 4-5 percentiles higher in children with CF in Canada than in those in the United States (P < 0.01), but percentages of ideal weight (104%) were similar in both populations. In adults with CF, mean height was similar at the 37th percentile; however, weight (26th compared with the 21st percentiles) and percentage of ideal weight (93% compared with 90%) were significantly higher in Canada than in the United States. Differences related to sex and age were similar in both countries for all indexes, which showed a high prevalence of underweight in infants and in older patients, but little sex discrepancy.

CONCLUSION

We observed substantially smaller differences in the growth indexes of CF patients between the United States and Canada compared with results from the 1980s. These findings reflect significant improvements in the nutritional status of US patients in recent years. However, caution is required in the direct comparison of mean percentiles from reports using different growth standards because there are systematic differences in growth standards, which affect, in particular, the comparison of growth in males and females.

Cystic fibrosis: nutritional consequences and management

Malnutrition is an adverse prognostic factor in cystic fibrosis, influencing the course of pulmonary disease and correlating inversely with survival. A positive energy balance between energy intake and the combination of total energy expenditure, energy losses and growth-related energy cost is essential to maintain normal nutritional status. Before starting nutritional supplementation, it is important to rule out pathological conditions that may have a deleterious effect on nutritional status: persistent exocrine pancreatic insufficiency, chronic bacterial pulmonary colonization, impaired glucose tolerance, specific nutritional deficits and associated disorders leading to a decrease of energy intake. Several methods are available, ranging from boosted oral nutrition to behavioural intervention, oral supplementation, enteral nutrition and, rarely, parenteral nutrition. The use of elemental nutrients for either oral supplementation or enteral nutrition seems of no nutritional benefit and is more expensive than conventional polymeric nutrients. Provided that the goals of the nutritional supplementation are fulfilled, simpler is often better.

Growth status in children with cystic fibrosis based on the National Cystic Fibrosis Patient Registry data: evaluation of various criteria used to identify malnutrition

OBJECTIVES

The objectives of this study were to determine growth status and to identify malnutrition with various anthropometric indicators in children with cystic fibrosis (CF) based on cross-sectional analysis of the 1993 National CF Patient Registry data.

METHODS

Heights and weights of 13,116 children with CF were evaluated with percentile, percent of reference median, Z-score, and percent ideal weight-for-height based on National Center for Health Statistics/Centers for Disease Control growth references. Malnutrition was defined by four criteria: (1) height-for-age <5th percentile ("stunting") or weight-for-age <5th percentile ("wasting") (2) height-for-age <90% of reference median or weight-for-age <80% of reference median, (3) height-for-age <5th percentile or percent ideal weight-for-height <85%, and (4) height-for-age <90% of reference median or weight-for-height <85% of reference median.

RESULTS

Mean and median height- and weight-for-age were found to be at the 30th and 20th percentiles in children with CF. Malnutrition (height- or weight-for-age <5th percentile) was particularly pronounced in infants (47%) and adolescents (34%) and patients with newly diagnosed CF (44%). A significant sex difference (p < 0.01) in the occurrence of stunting (height-for-age <5th percentile) was observed during adolescence: boys 11 to 14 years of age showed lower occurrence of stunting (19%) compared with girls (29%), whereas the opposite trend was observed at 15 to 18 years (34% in male patients vs 28% in female patients).

CONCLUSION

Twenty percent of all children in the 1993 National CF Patient Registry were <5th percentile for height- or weight-for-age. A significant discrepancy was found when different criteria were used to distinguish "stunting" versus "wasting" in malnourished children with CF.

Fat gram target to achieve high energy intake in cystic fibrosis

OBJECTIVE

Higher fat and energy intakes confer a survival advantage in cystic fibrosis (CF). There is a need to develop effective nutrition programmes that ensure optimal energy intake in CF.

METHODOLOGY

A cross-sectional measurement of clinical characteristics and energy and fat intakes in patients attending the CF outpatients clinic of the John Hunter Hospital, Newcastle was undertaken. Twenty-nine subjects, mean age 12 years (range 4.3-20.2), completed weighed food records to determine the contribution of fat to the percentage of the recommended energy intake obtained and to document use of pancreatic enzyme replacement therapy.

RESULTS

Diets with a high percentage of energy derived from fat did not guarantee that individuals with CF met their energy requirements. Subjects with total fat intakes of 100 g per day or greater, however, achieved in excess of 110% recommended daily intake (RDI) for energy. Up to 47% of subjects consumed more pancreatic enzyme replacement capsules than shown to give maximum effectiveness.

CONCLUSION

Setting a 100 g daily fat target is a realistic way of ensuring high energy intakes in CF. Fat ready reckoners would identify the fat content of food and prescribe specific numbers of pancreatic enzyme replacement capsules to be consumed with each meal or food item.

Long-term survival and nutritional data in patients with cystic fibrosis treated in a Danish centre

BACKGROUND

Adequate nutrition and optimal treatment of bronchopulmonary infections are both of critical importance in maintaining the health of patients with cystic fibrosis. The cystic fibrosis centre in Copenhagen has followed a regimen of very early and aggressive antimicrobial treatment, especially against Pseudomonas aeruginosa infection. An unrestricted diet of low fat and high protein without hyperalimentation was recommended before 1985 which was then changed to a high fat, high calorie intake.

METHODS

The overall impact of the treatment regimen was evaluated by a cross sectional analysis of all 223 patients who attended the centre in 1989. Growth and nutritional parameters were combined with lung function parameters and with a retrospective analysis of chronic P aeruginosa infection and its duration. Survival curves for all 313 patients treated at the centre since 1949 were calculated.

RESULTS

All the patients with cystic fibrosis had normal height, although the final height was achieved a little later than in healthy controls. Body weight was lower than normal in males above 15 and in females above 10 years of age. The body mass index (BMI), which was approximately 98% of normal in the younger patients, declined to 90% in adult men and to 83% in adult women with cystic fibrosis, and was strongly correlated with lung function parameters. In 1989 the median age of survival of all patients treated in the centre since 1949 was 30 years (32 years in males and 29 years in females).

CONCLUSIONS

The overall treatment regimen in the cystic fibrosis centre in Copenhagen is associated with growth and survival rates that are at least equal to those in other cystic fibrosis centres in other countries.

Disproportionate ileal digestion on canine food consumption. A possible model for satiety in pancreatic insufficiency

In animals, ileal sensors of nutrients signal satiety more potently than similar sensors in jejunum. We postulated that inadequate food intake and weight loss in human pancreatic insufficiency might arise by the displacement of digestion to ileum, where excessive release of digestive products would enhance satiety. To test this idea, we studied dogs prepared with pancreatic fistulas, which allowed reversible switching of pancreatic juice from entry at duodenum to entry at mid-small intestine. Dogs were studied in a crossover design over successive eight-day periods. Food consumption and body weight were measured while the dogs had continuous access to food. Diversion of pancreatic juice to mid-intestine significantly (P < 0.01) depressed food intake by an average of 28%. Diversion also significantly (P < 0.01) reduced body weight. The findings support the idea that insufficient food intake in human pancreatic insufficiency may result from stimulation of ileal satiety mechanisms.

The adolescent growth spurt in children with cystic fibrosis

The adolescent spurt in 230 children with cystic fibrosis (CF) treated at the Cleveland CF centre in northeastern Ohio was compared to that found in normal children from the Fels Longitudinal Growth Study in southwestern Ohio. The Preece-Baines Model 1 (PB1) growth equation was applied to longitudinal height data from both samples to describe a large number of data points for each child in terms of a few biologically meaningful parameters, such as age, height, and velocity at the take-off and peak of the adolescent growth spurt. The growth spurt is delayed by an average of 0.8 years and is about 1 cm/year slower at its peak in CF patients compared to the normal controls. This delay should be considered when comparing clinical growth measurements of adolescent CF patients with normal standards. Peak velocity is lower than expected, even for late-maturing normal children, and height at take-off, peak velocity, and adulthood is significantly reduced, especially in boys. These findings are consistent with the clinical impression that the growth spurt is delayed and attenuated in CF patients, particularly those with poor pulmonary function. Girls homozygous for the delta F508 mutation have significantly more growth retardation than those with other CF mutations.

Clinical pharmacology of pancreatic enzymes in patients with cystic fibrosis and in vitro performance of microencapsulated formulations

Improving protein and fat absorption in patients with cystic fibrosis relates to the amount of biologically active enzyme reaching the duodenum. Microencapsulated formulations are more effective than conventional products but differ in content, ability to retard acid inactivation and the pH at which they release enzymes. Contaminants in these products contribute to hyperuricosuria.

Resting energy expenditure. Evolution during antibiotic treatment for pulmonary exacerbation in cystic fibrosis

STUDY OBJECTIVES

To compare the changes in resting energy expenditure (REE) to concomitant changes in clinical status and pulmonary function in cystic fibrosis (CF) patients during treatment for acute pulmonary exacerbation. To determine if weight loss during exacerbation in CF is related to decreased calorie intake or increased energy needs.

DESIGN

Measurements of REE, pulmonary function tests, oxygen saturation, respiratory rate, maximal inspiratory pressure (MIP), white blood cell count, chest x-ray films and attribution of clinical score (ACS) on admission, mid-hospitalization, and discharge. Anthropometric measurements on admission, assessment of dietary intake and nitrogen balance upon admission and prior to discharge.

SUBJECTS

Thirteen CF patients admitted for treatment of acute pulmonary exacerbation with a mean age of 11.0 +/- 7.9 (SD) years.

RESULTS

From admission to discharge, REE decreased from 44.5 +/- 9.0 to 33.8 +/- 8.5 kilocalorie (kcal)/kg/d (p < 0.003). Similarly, the ACS improved from 7.5 +/- 2.0 to 4.0 +/- 2.2 (p < 0.0001); the absolute neutrophil count decreased from 10,685 +/- 6,226/microliters to 6,363 +/- 168/microliters (p < 0.005); respiratory rate decreased from 32.6 +/- 6.2 to 25.0 +/- 3.7 breaths per minute (p < 0.01); and MIP increased from 77.5 +/- 20.0 to 90.0 +/- 20.4 cm H2O (p < 0.01). In parallel, less significant improvements occurred in pulmonary function tests, oxygen saturation and chest x-ray film scores. Calorie intake was 1,893 +/- 635 and 2,054 +/- 707 kcal/d on admission and discharge, respectively (p = NS); during hospitalization, weight increased from 23.6 +/- 10.1 to 25.7 +/- 10.1 kg (p < 0.005). While carbohydrate and fat content of the diet remained essentially unchanged, a significant increase in protein intake (3.15 +/- 0.92 to 3.5 +/- 0.81 g/kg/d [p < 0.05]) and in nitrogen balance (1.8 +/- 2.5 to 5.6 +/- 2.9 g of nitrogen per day [p < 0.05]) were observed.

CONCLUSIONS

In acute CF, pulmonary exacerbation, changes in REE parallel those of clinical improvements and are more sensitive than pulmonary function tests and chest x-ray films as an objective clinical correlate. Increased metabolic requirements but not decreased dietary intake are the cause of weight loss in CF patients.

Linear growth in children with cystic fibrosis. I. Birth to 8 years of age

The linear growth of Swedish children with cystic fibrosis (CF), is described using the infancy-childhood-puberty (ICP) growth model. Length/height was studied in 51 patients during their first 8 years of life. The median age at diagnosis was 0.4 years (range 0.0-6.1 years). At birth, their mean length was close to normal, but the gain in length over the first 0.25 years of life was significantly below normal, resulting in a mean length SDS of -1.3. Length remained subnormal up to 1.0 year of age. Thereafter, catch-up growth occurred, resulting in almost normal height (mean SDS-0.3) at 5.0 years of age. Between 5.0 and 8.0 years of age growth was normal. The mean age at onset of the childhood component was not significantly different from the controls. Hence, the catch-up growth did not occur until after the onset of the childhood component. This study shows that the postnatal linear growth rate is retarded in children with CF during the first months of life. This is almost completely compensated for by a supranormal growth rate that starts at the end of the first year of life.

Differentially delayed development in the hand-wrist skeletons of children with cystic fibrosis: Round versus tubular bones

From a sample of 50 cystic fibrosis patients in whom a previous study had demosntrated a lack of statistical interdependence between disease severity and significant TW2-20 bone age delays, hand-wrist radiographs for a preadolescent subsample of 30 (14 females and 16 males, 7.4 to 13.0 years of age) are reassessed using the TW2 method to (1) elucidate any significant differences in maturational delays exhibited by the carpals and the tubular bones (radius, ulna, and short bones [RUS]) of the hand-wrist complex and (2) assess the relationships between the clinically derived measure of pulmonary disease severity, anthropometric indices of nutritional status, and the bone age delays in these two regions. Female and male carpal bone age delays, pulmonary disease severity scores, and weight/height² differ significantly. However, both sexes exhibit significant mean TW2-carpal bone age delays, while mean TW2-RUS ages are either non-significantly delayed or advanced with respect to normative standards. Correlation and all-subsets multiple linear regression analyses reveal no significant interdependence or predictive relationships between clinically derived measures of pulmonary disease severity and anthropometric measures of nutritional complications and delayed skeletal maturation in either the carpals or tubular bones of the hand-wrist complex.

Early childhood growth in patients with cystic fibrosis

Longitudinal recumbent length data on 65 cystic fibrosis (CF) patients from 3 months to 6 years of age were used to fit two mathematical models of early childhood growth. The results were compared to published data from the Longitudinal Studies of Child Health and Development at the Harvard School of Public Health. The median values for girls with CF indicate essentially normal growth in the first year of life, whereas CF boys are slightly smaller than normal boys. Both sexes show declines in length relative to normal children in later years. This pattern is reflected in significant deviations from normal values in growth curve parameters for CF patients. While the linear Reed model gave a slightly better fit to the data, the non linear Jenss model allowed easier interpretation of parameters and comparisons with the Boston children. Early childhood growth in cystic fibrosis is characterized by fairly normal exponential growth in the first year of life followed by an earlier approach to a linear asymptote than is found in normal children. Although both the raw data and curve parameters were much more variable in CF patients than in the Boston sample, there were no significant differences in growth between patients diagnosed in infancy because of disease symptoms as opposed to those diagnosed because of family history alone. The appearance of growth retardation in CF primarily after infancy suggests that the cumulative effect of chronic digestive or pulmonary malfunctions, rather than a basic metabolic defect, is responsible for much of the growth retardation seen in these children.

Nutritional status, growth and development in children undergoing intensive treatment for cystic fibrosis

Dietary intakes were measured over a period of 5 days in 36 malnourished and 36 well-nourished patients with cystic fibrosis. Both energy and protein intakes were significantly less in the malnourished patients for the two age groups studied: 4-9.99 years (p less than 0.01 for both parameters), and 10-16 years (p less than 0.05 and p less than 0.01, respectively). In both age groups and both patient groups, average protein intakes were well in excess of the recommended daily intake, but energy intake in the malnourished patients was below the recommended daily intake. Nutritional supplementation of 10 malnourished patients with a polymeric formula, infused overnight via a gastrostomy tube, resulted in a seven-fold increase in weight gain (p less than 0.001) and a doubling of linear growth velocity (p less than 0.01) over a period of 18 months, compared to the 18 months prior to gastrostomy feeding. Measurements of total body nitrogen in eight of these patients demonstrated a 38% increase in body nitrogen content over 12 months, indicating a replenishment of the protein deficit.

Malnutrition in cystic fibrosis: psychosocial functioning of patients and their families

The relationship between nutritional status and psychosocial functioning was examined in 35 children with cystic fibrosis, aged 7-16 years. Twelve malnourished children and their families were compared with 23 well nourished children and their families. Established measures of adjustment and coping in the children, parents and families were used. Few statistically significant differences between the two groups emerged, and all comparisons of psychosocial functioning were not significant. The results of the study suggest that there is no relationship between the nutritional status of the child with cystic fibrosis and the current psychosocial adjustment and coping of child, parents and family.

Gastrointestinal dysfunction and its effects on nutrition in CF

Prevention of malnutrition, a consequence of elevated energy requirements, increased losses and low caloric intake, is one of the main goals in the treatment of cystic fibrosis. Caloric stool losses, catch-up growth and an elevated energy expenditure, even in the absence of overt lung disease and malabsorption, have led to recommendations for a caloric intake of 120-150% of the recommended daily allowances. A high energy intake with a fat content of at least 40 calorie % and adequate pancreatic supplementation has shown to improve growth and median age of survival. As a rational treatment of the fundamental disturbance in cystic fibrosis, a decrease in chloride permeability across epithelia, is not yet available, treatment should be concentrated on adequate nutritional support in combination with optimal correction of those gastrointestinal abnormalities including faecal bile acid loss, small intestinal abnormalities, pancreatic insufficiency, hormonal abnormalities and disturbances in gastrointestinal motility, which may aggravate maldigestion and malabsorption.

Fat intake is low in cystic fibrosis despite unrestricted dietary practices

A prospective study of caloric intake and specific nutrient composition was performed in 64 cystic fibrosis patients aged 0.3 to 18 yr. Linear regressions and multiple stepwise regressions revealed no significant correlations between any individual dietary parameter and age, height, weight, percentile of weight or height, Shwachman Score, and pulmonary parameters. The caloric intake varied widely in individual patients and in different age groups. Despite unrestrictive dietary practices, the fat intake (33.7% +/- 8) was below that recommended for these linoleate deficient patients.

Increased energy expenditure in young children with cystic fibrosis

To investigate the role of energy expenditure in the altered energy balance in cystic fibrosis (CF), total energy expenditure (TEE) was measured by the doubly-labelled water method in 9 clinically well CF infants (body weight 7.3-10.9 kg) without chronic lung disease. CF infants had 25% higher rates of energy expenditure when compared with data derived from measurements of TEE obtained by the same method in 16 healthy infants, matched for age and body weight. Mean TEE (SEM) for CF was 950 (38) kcal, vs 876 (72) kcal for controls matched for age and 758 (46) kcal for controls matched for weight. Although subclinical disease activity cannot be excluded as a determinant of the excess TEE, the possibility of an energy-requiring basic defect is suggested, because further analysis indicated that factors other than body weight, degree of underweight, presence of pancreatic insufficiency, or presence of lung disease were important. Increased TEE may contribute to undernutrition in CF, even in the absence of chronic lung disease.

Diet for cystic fibrosis. Nutritional requirements and prescriptions

Diet plays no direct role in neutralizing the effects of the basic defect in cystic fibrosis, but it can prevent some of the acquired damage caused by complications. Adequate caloric intake provides the energy needed for exercise and cell metabolism, a strong diaphragm, normal cellular immunity, and a positive psychological outlook. Clinical management is aimed at achieving good nutrition. Patient education about nutrition and use of dietary supplements should be started immediately upon diagnosis. Careful clinical examinations and regular follow-up are necessary to detect complications that will interfere with good nutrition. Complications must be treated aggressively. Psychological and social stresses need to be recognized, and psychological referral may be necessary. The clinician's best tools to achieve these goals are the patient's dietary and gastrointestinal history, the anthropometric measurements taken at each office visit, regular patient assessment, and constant attention to detail in monitoring and charting the course of disease. Extraordinary measures, such as nighttime feedings by nasogastric or gastrostomy tube and intravenous hyperalimentation, may be necessary. For best results, these measures must be started before pulmonary complications threaten survival.

Review: pancreatic enzyme replacement--applied physiology and pharmacology

The treatment of pancreatic steatorrhoea can often be improved by attention to the pathophysiological and pharmacological principles involved. Factors influencing the efficacy of pancreatic enzyme replacement include physiological characteristics of the individual patient and pharmaceutical characteristics of the supplement. Different patients may be best suited by different preparations and there is no overall 'best buy'. The new enteric-coated microsphere formulations are often most effective, but also more expensive than conventional preparations. Adjunctive H2-blockade can help appropriately selected patients with resistant steatorrhoea. Knowledge of the underlying cause may guide the choice of supplement and its dose, but trials of different regimens may prove necessary. Successful management, particularly of malnourished patients, involves optimization of dietary fat intake in addition to enzyme replacement.