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Cystic Fibrosis
Cystic fibrosis is a genetically inherited, autosomal recessive, chronic disease affecting
roughly 1 in every 2500 children born in the United States.
Here are some facts about cystic fibrosis:
 Median age of survival is 37 years
 Chloride and sodium cannot move across cell membranes; this causes mucus to become
thicker and more viscous
 Adverse effects are seen in the respiratory system, pancreatic system, gastrointestinal
system, sinuses, liver, spleen, sweat glands, and reproductive systems
 Respiratory failure is the most common cause of death
 The lungs become a breeding ground for bacterial colonization, particularly of
Pseudomonas aeruginosa, which leads to repetitive pulmonary infections and
permanently injured lung tissue
 Nutrition is a serious issue for patients with cystic fibrosis because the thick, sticky
mucous secretions block the pancreatic duct, and the enzymes amylase, lipase, and
protease are unable to get to the small intestine to break down the food
 Nearly 90% of all cystic fibrosis patients will present with pancreatic insufficiency or
pancreatic failure
Diabetes mellitus
Up to 75% of adults with cystic fibrosis may have some form of glucose intolerance, and
up to 15% may have frank cystic fibrosis-related diabetes (CFRD).
Here are some facts about cystic fibrosis and diabetes mellitus:
 Some cystic fibrosis patients develop intermittent diabetes during times of acute illness
or when taking steroids
 Women with cystic fibrosis who become pregnant are at very high risk for gestational
diabetes
 CFRD has features of both type 1 and type 2 diabetes, combining both insulin
resistance and insulin deficiency
 Carbohydrate counting still is used, just with more allowable carbohydrate choices
 40% of total energy should come from fat and 45% to 50% should come from
carbohydrate
 Refined sugar is allowed liberally throughout the day, but as part of a full and balanced
meal
 Any time that there is a conflict between dietary therapy of cystic fibrosis and diabetes
mellitus, cystic fibrosis wins
 Do not limit protein intake
Malnutrition
The following issues can lead to malnutrition:
 Pancreatic insufficiency
 Progression of pulmonary disease
 Chronic infection
 Increased resting energy expenditure
 Anorexia or other feeding disorders
 Diabetes
 Gastroesophageal reflux or esophagitis
 Depression, denial, and other psychological factors
 Abnormal adaptive response to malnutrition
 Poor adherence to medication and supplementation regimen
 Gastrointestinal complications, including distal intestinal obstruction syndrome,
occurring in 10% to 47% of patients
 Decreased fat catabolism, if hepatobiliary disease is present
 Fever
Treatment
Medications include:
 Anti-inflammatories
 Antibiotics (tobramycin and gentamicin are common)
 Mucolytic agents
 Pancreatic enzymes
 Steroids
 Bronchodilators
Airway clearance treatments, also known as chest physical therapy, include cupping or
clapping the child’s back or using a motorized vest that vibrates to help remove
secretions from the lungs.
The team approach
Members of the team can include the following health care professionals:
 Physician
 Endocrinologist
 Respiratory therapist
 Dietitian
 Nurse specializing in cystic fibrosis
 Social worker
 Psychologist
Clinical tests
The following tests are commonly used:
 Sputum culture for nontuberculous mycobacteria
 Chest X-ray
 More detailed lung-function tests, as necessary
 Blood gases, as necessary
 Complete blood count
 Liver function tests
 Fat-soluble vitamin levels
 Fecal fat test
 Fasting blood glucose
 Electrocardiogram, as necessary
Diet
The diet includes high-protein, high-fat, high-sodium, and high-calorie foods. The
following are facts pertaining to the diet of the cystic fibrosis patient:
 Diet is often 120% to 150% Recommended Dietary Allowance for total calories, with
35% to 40% calories from fat
 Many patients require tube feeding for supplemental nutrition
 People with cystic fibrosis require supplementation of fat-soluble vitamins
 Osteopenia is common in people with cystic fibrosis, with causes including:
– Deficiency of vitamins D and K
– Deficiency of calcium
– Failure to thrive
– Delayed puberty
– Liver disease
– Inactivity
– Corticosteroid usage
 Iron deficiency caused by inadequate intake, malabsorption, chronic infection, and/or
blood loss is common
 Zinc deficiency is possible, but difficult to diagnose because plasma zinc levels are not
always impacted:
– Zinc supplementation is useful for some patients with failure to thrive or short stature
– Supplementation is sometimes recommended for those with low vitamin A levels,
because zinc deficiency affects vitamin A status
 Medium-chain triglyceride (MCT) oil is often used for cystic fibrosis patients, because
it is more easily digested than other fats:
– MCTs do not require carnitine to enter mitochondria and are transported directly to
liver via portal circulation
– The benefits of MCT usage include decreased steatorrhea, weight gain, and increased
serum albumin levels
 For patients who sweat from activity or heat, encourage the consumption of sports
beverages with added salt
 Poor dietary intake of sodium can worsen growth problems
Initiation of enteral tube feeding
 Children—weight for height of <85%, weight falling 2 centile positions, or no weight
gain for 6 months
 Adults—body mass index <19, >5% weight loss over more than 2 months, or failure to
gain weight during pregnancy
Note: Never put enzymes in the tube.
Infancy
Breastfeeding is recommended for infants with cystic fibrosis because:
 The lipase and amylase excreted in breast milk may help to compensate for decreased
pancreatic secretion of the infant
 Immunological properties of breast milk are especially helpful
 The fatty acid profile of breast milk may help to maintain/improve the essential fatty
acid status of the infant
 Breast milk contains taurine, which is used in bile salt synthesis and may enhance fat
absorption
Whey-based formulas also are acceptable. Demand feeding is appropriate for both
breastfeeding and bottle feeding. You may need to recommend adding salt to baby food,
because commercial manufacturers do not.
Pancreatic enzymes
Pancreatic enzyme therapy often is started before 1 year of age. The amount of enzyme
prescribed is not based on age or weight, but on the level of natural enzymes utilized and
the individual’s diet. Some people with cystic fibrosis take the same amount of enzymes
with each meal, while others alter their dosage based on the amount of protein and fat
present in a particular meal.
It is important to remember these facts:
 Use the smallest dose of enzymes capable of controlling steatorrhea and achieving a
normal pattern of growth
 Capsule dose is a minimum—pills often are overfilled to compensate for degradation
during storage (actual dose provided by a capsule may exceed the stated dose by 20%
to 50%)
 Most patients require 50 to 100 international units (IU) lipase/gram dietary fat/kilogram
/day in infancy and young childhood
 Pancreatic enzymes impair iron absorption
References and recommended readings
Antioxidant therapies for cystic fibrosis. Cystic Fibrosis Foundation Web site.
http://www.cff.org/treatments/Therapies/AlternativeTherapies/Antioxidants.
Accessed April 15, 2013.
Brunzell C, Hardin DS, Moran A, Schindler T, Schissel K. Managing Cystic FibrosisRelated Diabetes “(CFRD)”: An Introduction Guide for Patients and Families. 4th ed.
Bethesda, MD: Cystic Fibrosis Foundation; 2008.
http://www.cff.org/UploadedFiles/LivingWithCF/StayingHealthy/Diet/Diabetes/CFRDManual-4th-edition.pdf. Accessed April 15, 2013.
Casey S, Fulton J. Building Block for Life: A Summary of the Cystic Fibrosis Foundation
Consensus Nutrition Guidelines for Pediatric Patients. Chicago, IL: Pediatric Nutrition
Practice Group of the American Dietetic Association; 2002:1-9.
CF care guidelines—nutrition/GI. Cystic Fibrosis Foundation Web site.
http://www.cff.org/treatments/CFCareGuidelines/Nutrition/. Accessed April 15, 2013.
Cystic fibrosis. University of Maryland Medical Center Web site.
http://www.umm.edu/altmed/articles/cystic-fibrosis-000045.htm. Accessed March 13,
2013.
Dietetics Pediatric Nutrition Care Manual®. Academy of Nutrition and Dietetics Web site
[by subscription]. www.nutritioncaremanual.org. Accessed April 15, 2013.
Review Date 4/13
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