Cystic Fibrosis

Question 1

Cystic fibrosis background

Answer 1

Respiratory issue related to mucous production AND GI issues related to blockage of pancreatic ducts
* disorder of mucous function which protects against bacterial infiltration of lungs so when abnormal it clumps and prevents lungs from expanding making it easier for bacteria to get in.
* Also get mucous that blocks the pancreatic ducts preventing enzymes to be released into the small bowel in response to eating.

Question 2

nutritional consequences of cystic fibrosis?

Answer 2

Fat and Fat MALABSORPTION

Question 3

Diagnosis

Answer 3

2 positive sweat chlorides
* disease interferes with how sodium is taken up

Question 4

Newborn screening for CF

Answer 4

1. Elevated IRT (Immunoreactive Trypsinogen): IRT is a protein made by the pancreas. IRT can be elevated for a number of reasons, including cystic fibrosis (CF).
2. If IRT high do DNA testing for the 40 most common CF mutations

Question 5

Clinical features of CF

Answer 5

• Chronic sinopulmonary disease, nasal polyps, digital clubbing
• GI abnormalities: FTT, steatorrhea, fat-soluble vitamin deficiencies, DIOS (Distal Intestinal Obstruction Syndrome), chronic pancreatitis, hepatic manifestations
• Salt loss syndromes

Question 6

Role of genetics in physiology of CF

Answer 6

CFTR codes for Cl- channel in apical surface of cell membrane of exocrine glands
* Effects: inability to move Cl- OUT of cells, increased movement of Na+ INTO cells
* Net water movement into cell → thick tenacious secretions

Discovering the gene and treating to malnutrition changed the landscape from lifespan from 12 to 80

Question 7

Consequences of CF

Answer 7

• respiratory
• gastrointestinal
• pancreatic
• reproductive

Question 8

Respiratory manifestations of CF

Answer 8

Infection, chronic cough, wheeze, shortness of breath:
* Thick secretions trap bacteria → infection
* Air trapping → “barrel-chest”
* destruction of lung tissue → respiratory failure

Question 9

GI manifestations of CF

Answer 9

Intestinal obstruction (10-20% of children with CF), liver failure (cirrhosis)
* thick meconium obstructs GI tract → vomiting, abdominal distention
* obstruction of biliary system → cirrhosis (13- 17%)
* meconium ileus (thick and tarry black stool in newborns)
* distal intestinal obstruction syndrome (DIOS)

may require surgical intervention

Question 10

Pancreatic manifestations of CF

Answer 10

pancreatic insufficiency
* Affects 85% of CF patients at birth, additional 5-10% by end of 1st year
* primarily affects digestive enzymes
* diabetes mellitus: 3% (5-9 yr), 11% (10-19 yr), 15% (>20 yr)

Question 11

pathophysiology of pancreatic insufficiency of CF

Answer 11

Pancreatic destruction
↓
insufficient digestive enzymes
↓
protein/fat maldigestion
↓
significant energy loss/FTT

Question 12

Reproductive system manifestations of CF

Answer 12

• Congenital absence of vas deferens in >95% → male infertility
• female fertility reduced due to thickened cervical mucous → pregnancy still possible

Question 13

CF therapy

Answer 13

• Pulmonary: Antibiotics, bronchodilators, chest physiotherapy
• Nutritional: kcal (120-150% Reference nutrient intakes), Vitamins ADEK, enzymes, supplemental feeds
• Other therapies as needed (intestinal obstruction, liver disease, diabetes)

Question 14

Future in nutritional therapy for CF

Answer 14

Nutrition support
* Improved monitoring techniques - functional/structural
* Improvements in supplementation techniques

Nutritional interventions
* “normalization” of FA metabolism
* Modulation of inflammatory response