Case 26

Question 1

What are key findings from the history in a 9 week old diagnosed with CF?

Answer 1

Poor weight gain, good caloric intake, loose stools, good parenting skills, negative ROS.

Question 2

What are key physical exam findings in a 9 week old diagnosed with CF?

Answer 2

Thin, little subQ fat, pallor, no dysmorphic features, elevated HR.

Question 3

What is on the differential diagnosis for CF?

Answer 3

Malabsorption, formula allergy, improperly prepared formula, psychosocial failure to thrive, inadequate formula volume, congestive heart failure

Question 4

What are key findings from testing for CF?

Answer 4

Anemia, elevated sweat chloride

Question 5

Normal vitals for a newborn:

Answer 5

3.5 kg, HR 100-160, RR 30-60

Question 6

Normal vitals for a 6 mo old:

Answer 6

7 kg, HR 110-160, RR 24-38

Question 7

Normal vitals for a 1 yo:

Answer 7

19 kg, HR 90-150, RR 22-30

Question 8

Normal vitals for a 3 yo:

Answer 8

14 kg, HR 80-125, RR 22-30

Question 9

Normal vitals for a 5 yo:

Answer 9

18 kg, HR 70-115, RR 20-24

Question 10

Normal vitals for a 10 yo:

Answer 10

33 kg, HR 60-100, RR 16-22

Question 11

Normal vitals for a 12 yo:

Answer 11

40 kg, HR 60-100, RR 16-22

Question 12

Normal vitals for a 14 yo:

Answer 12

50 kg, HR 60-100, RR 14-20

Question 13

Assessing weight gain:

Answer 13

• Wt. is the most sensitive indicator or nutritional status
• Wt. loss immediately after birth rarely greater than 10 percent of birth weight
• Healthy infants gain approximately 20-30 grams per day during the first four months of life
• Wt. typically doubles by about 4 mo
• Formula-fed infants tend to gain weight faster than breastfed infants because they ingest more calories
• Reduced linear growth usually indicates more severe, prolonged malnutrition
• The brain is preferentially spared in protein-energy malnutrition, so reduced growth in head circumference occurs late and indicates very severe or longstanding malnutrition

Question 14

What is the definition of FTT?

Answer 14

FTT (or lack of physiologic growth and development) is the term used to describe poor weight gain in children when:

• Weight less than 3rd percentile
• Weight for height/length is less than 3rd percentile
• Rate of growth slows compared to previous growth, crossing two or more major percentiles downward

Question 15

What are the two categories of failure to thrive?

Answer 15

Organic FTT and Non-organic FTT

Question 16

Organic FTT:

Answer 16

Growth failure caused by an acute or chronic disorder that results in inadequate nutrient intake, malabsorption of nutrients, or increased energy requirements. Common organic causes of FTT in infants include:

• Chronic diarrhea
• Formula allergy
• Congenital heart defects
• Cystic fibrosis
• Developmental deny with poor suck and swallow
• Renal tubular acidosis
• Vomiting caused by severe GERD or bowel obstruction

Question 17

Non-organic FTT:

Answer 17

Growth failure not resulting from an underlying disease or disorder (nearly ninety percent of FTT cases). Inadequate caloric intake may result from:

• Poverty
• Poor understanding of feeding techniques
• Improperly prepared formula
• Inadequate supply of breast milk
• Neglect of the infant (i.e., lack of food)
• Less commonly, there is a psychological basis of non-organic FTT in which stimulation is lacking because caregiver is depressed, has poor parenting skills, or is responding to real or perceived external stresses.

Question 18

Causes of anemia in an infant:

Answer 18

• Chronic disease
• Hemolysis
• Blood loss
• Physiological anemia
• Iron deficiency

Question 19

Chronic disease:

Answer 19

Chronic disease or inflammation can cause a normocytic, normochromic anemia

Question 20

Hemolysis:

Answer 20

Causes a decreased total number of red blood cells (RBCs) and damages the remaining RBCs. A peripheral blood smear can be obtained to assess RBC morphology.

Question 21

Blood loss:

Answer 21

Causes a normocytic, normochromic anemia.

Question 22

Physiological anemia:

Answer 22

A decrease in hemoglobin occurs in infants because fetal RBCs have a short half-life. In full-term newborns the marrow is not stimulated to produce new RBCs until the hemoglobin reaches its nadir of about 11 g/dL (110 g/L at 7-9 weeks of age, after which the hemoglobin rises.

Question 23

Iron deficiency:

Answer 23

Leads to microcytosis along with a low Hgb. However, iron deficiency does not manifest this early in full-term infants unless there is blood loss.

Question 24

Pathophysiology of Cystic Fibrosis:

Answer 24

Caused by mutations in CFTR (cystic fibrosis transmembrane conductance regulator, or CFTR). When the CFTR protein is defective, results in disturbed salt balance and buildup of mucus, disrupting normal function of body organs - particularly the pancreas and lungs. This can lead to malabsorption of nutrients in the GI tract and chronic infection and inflammation of the lungs.

Question 25

What are the symptoms of cystic fibrosis?

Answer 25

Some individuals have mild symptoms - such as a chronic cough, recurrent bronchitis, or sinusitis - for years before a diagnosis is made. A significant number of patients with CF, 85-90 percent, have pancreatic insufficiency and present with steatorrhea and malabsorption. Today, however, the vast majority of infants with CF are identified by newborn screening, not by symptoms. Making the diagnosis earlier has made a big difference in how well babies and children with CF grow.

Question 26

Inheritance of CF:

Answer 26

CF is an autosomal recessive disorder. Most people with CF do not have a positive family history.

Question 27

Diagnosis of CF:

Answer 27

• The sweat chloride test is the main diagnostic test, although genotyping is adjunctive
• Genetic testing for mutations of the CFTR gene supports the diagnosis of CF but is generally not sufficient for diagnosis alone. Genetic testing is important as new methods of treatment for CF become available that may be able to correct specific gene mutations.

Question 28

Neonatal metabolic screening:

Answer 28

All states require screening for PKU and hypothyroidism. In addition, there may be screening for galactosemia, hemoglobinopathy, biotinidase deficiency, congenital adrenal hyperplasia, maple syrup urine disease, homocystinuria and CF.

Question 29

What is on the differential diagnosis for CF?

Answer 29

Malabsorption, Formula allergy, Psychosocial FTT (inadequate resources), Congestive heart failure

Question 30

Malabsorption:

Answer 30

History of poor weight gain with good caloric intake and loose stools makes malabsorption leading diagnosis.

Question 31

Formula allergy:

Answer 31

True milk-protein allergy typically causes intestinal blood loss (either gross or occult). Infants are usually fussy and may vomit. Poor weight gain as an isolated finding is unusual.

Question 32

Psychosocial FTT (inadequate resources):

Answer 32

Inadequate caloric intake may result from poverty, poor understanding of feeding techniques, improperly prepared formula, or inadequate supply of breast milk. It occasionally reflects neglect of the infant (eg, lack of food)

Question 33

Congestive heart failure:

Answer 33

Important to consider in any child with failure to thrive. History would likely include difficulty feeding and respiratory distress.

Question 34

Occult blood, stool:

Answer 34

May indicate milk protein intolerance

Question 35

CXR:

Answer 35

Look for cardiomegaly and pulmonary infiltrates.

Question 36

CBC:

Answer 36

A CBC and review of the peripheral blood smear assist in identification of anemia or possible infection.

Question 37

Blood urea nitrogen (BUN) and creatinine:

Answer 37

Poor growth may reflect kidney failure.

Question 38

Electrolytes:

Answer 38

Important in evaluating hydration status, renal function, and acid-base status.

Question 39

Fecal elastase:

Answer 39

Helpful in evaluating for pancreatic insufficiency

Question 40

Fecal fat analysis:

Answer 40

Lipase, one of the key products of exocrine pancreatic secretion, is necessary for absorption of fat from the diet. In its absence, fat is malabsorbed and is excreted in the stool. A single sample of stool may be stained for fat to identify malabsorption. A more complete analysis is to perform a 72-hr stool collection and quantify the amount of fat in the stool compared to oral intake of fat during the same time period.

Question 41

Liver function tests:

Answer 41

May suggest congenital or acquired infection or presence of biliary congestion.

Question 42

Sweat Chloride Test:

Answer 42

This test has been used in the diagnosis of CF since it was developed in 1959. An abnormal sweat test in someone with symptoms consistent with CF is most likely to indicate CF, but there are causes of false positive or false negative sweat tests that need to be considered (false negatives can occur with a specific, rare CF mutation; false positives can occur with a number of metabolic disorders, including adrenal insufficiency and hypothyroidism). The sweat chloride test has a sensitivity of 99 percent and specificity of near 90 percent.

Question 43

Genetic testing for CF:

Answer 43

If genetic testing is not done as part of the diagnostic workup, most CF experts now recommend genotyping of patients with CF in order to identify their specific mutations. Although gene therapy for CF is not yet a reality, there are studies currently evaluating not only gene therapy but also medications that address specific mutations in CF.

Question 44

Nutritional management of CF:

Answer 44

• Pancreatic enzyme and vitamin replacement
• Also need to provide calories at a level greater than the recommended dietary allowance for age to maintain appropriate nutritional status.

Question 45

Airway inflammation and infection:

Answer 45

Because of the plugging of the airways with mucus, children with CF have lots of lung infections and can develop pneumonia.
-Pulmonary infections are difficult to treat and require prompt attention.

Question 46

How often do CF patients require follow up?

Answer 46

Usually at least every 3 months at a CF center.