26 Flashcards
Failure to thrive - most common cause
Means of that cause
Inadequate calories to meet metabolic need
There are three means of inadequate calories:
Insufficient intake
Excessive losses
Excessive caloric need.
Allergy, chronic disease, endocrine disorders, genetic syndromes, parental neglect and poverty all may result in failure to thrive because the infant may not receive sufficient calories to support growth.
Diff dx for failure to thrive 5
Congestive heart failure (CHF)
CHF is important to consider in any child with FTT.
Difficulty feeding and respiratory distress would commonly be described.
Formula allergy
True milk-protein allergy is difficult to diagnose, but typically causes intestinal blood loss (may be gross or occult).
These children may also have fussiness, particularly after feeds and vomiting.
Gastroenteritis
Gastroenteritis may cause FTT, but is typically associated with both vomiting and diarrhea and may also be associated with fever and/or bloody stools.
Some infectious etiologies (e.g., giardia) have a more indolent, chronic course.
Hypothyroidism
Hypothyroidism may cause FTT in a young infant.
Infants with hypothyroidism tend to have poor feeding and constipation rather than eager feeding and increased stools.
Malabsorption
A history of poor weight gain in the setting of good caloric intake and the presence of loose stools is concerning for malabsorption.
Some tests that can be done for FTT
BUN and creat
Important to check because poor growth may reflect renal failure.
Chest x-ray
Chest x-ray is important to look for cardiomegaly and pulmonary infiltrates.
CBC and smear
CBC and a review of the blood smear will assist in the identification of an anemia or infection.
Electrolytes (serum)
Electrolytes are important in the evaluation of hydration status, renal function, and acid/base status.
Fecal fat analysis
Fecal fat collection will identify fat malabsorption.
A sample of stool may be stained for fat and may identify fat globules, but a more complete analysis would include a 72-hour stool collection and measurement of total fat in stool compared to oral intake over the 72-hour time period.
Another potential test is fecal elastase, which can be helpful in evaluating for pancreatic insufficiency.
Liver function tests
If abnormal, might suggest congenital or acquired infections or conditions that can cause biliary congestion, such as cystic fibrosis.
Neonatal screen
There are several conditions that can be detected by newborn screening that may be associated with FTT.
Occult blood, stool
Occult or frank blood in the stool of infants may indicate milk protein intolerance.
Another test that might be useful is stool reducing substances, which can be present in protein malabsorption, among other conditions.
Ova and parasites, stool
May indicate a parasitic infection.
Stool culture
May indicate parasitic or other organism such as Salmonella or Campylobacter.
Sweat chloride
Apart from newborn screening, a sweat chloride test is currently the best screening and diagnostic test for cystic fibrosis.
Screening sweat tests are performed at many hospitals and laboratories, but the diagnosis of CF should only be made on the basis of sweat tests that are performed at accredited laboratories, which are usually associated with CF centers.
Thyroid function tests
Thyroid hormone deficiency is an important cause of FTT that can be picked up on neonatal screen.
Urinalysis
Urinalysis is important in assessing for renal dysfunction such as renal tubular acidosis, hematuria, UTI, etc.
Urine culture
Urine culture would be indicated if the urinalysis is abnormal or if there is a history of fever.
Anemia -normal RBC values in infants
Etiology
Normal RBC Values in Infants
The mean value for hemoglobin for healthy full-term 2-month-old infants is 11.2 g/dL (112 g/L), an anticipated drop from the mean hemoglobin at birth of 16.5 g/dL (165 g/L).
The decrease in hemoglobin occurs because fetal RBCs have a short half-life that leads to a “physiological nadir” for hemoglobin, sometimes also called “physiological anemia.”
In full-term newborns the marrow is stimulated to produce new RBCs only when the hemoglobin reaches its nadir of about 11 g/dL (110 g/L) at 7-9 weeks of age, after which the hemoglobin rises.
Etiology
There are many causes of anemia in infants, among them:
Iron deficiency (causes a microcytic anemia)
Chronic disease (can cause a normocytic, normochromic anemia)
Hemolysis (causes a drop in the total number of red blood cells and damages the remaining RBCs)
Blood loss (causes a normocytic, normochromic anemia)
Tests for CF 3
Sweat chloride greater than or equal to 60 mg/dl is most consistent with CF. Has to be done again if no newborn screen done, if sweat positive after newborn screen shows CF then no further tests needed
Newborn Screening
Many states now identify CF by the neonatal screening program that detects immunoreactive trypsinogen in blood, with confirmatory tests done to make the final diagnosis. In babies with cystic fibrosis, mucous plugs can block the pancreatic ducts that lead into the small intestines, preventing trypsinogen from reaching the intestines resulting in a buildup of the protein in the blood.
Genotyping
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.
Inheritance pattern of CF
Cystic fibrosis is an autosomal recessive disease. For an infant to have the disease, both parents must be heterozygote carriers of the mutant allele. Each child of this couple have will have a 25% chance of having CF, a 25% chance of being unaffected, and a 50% chance of being a carrier like his parents.
In other words, CF has to be in both the mother’s and the father’s family in order for a child to have the condition. However, most people with CF don’t have a positive family history for the disease, as it is inherited in an autosomal recessive pattern.
Genetic Counseling
Because of the inheritance pattern, parents of a child with CF have the chance of having another child with CF in the future. The potential for screening parents or for offering prenatal screening for CF should be discussed.
Parents may benefit from speaking with a genetic counselor.
It is also important that the particular CF genotype be determined, since the type of mutation may have an impact on disease course and future treatment options.
CF - approach to care and tx
Outcomes
Multipronged Approach to Care
One of the primary problems in CF is inflammation in the lungs, probably related to the chronic infection but also due to the underlying genetic problem. Some of the treatments target the airway inflammation, some of them target the infection, and some of them target both.
Treatment is multi-pronged and includes:
Nutritional management, with enzymes and vitamins and extra calories
Airway clearance, and
Treatment of airway infections.
Improved Outcomes
There is not yet a cure for all patients with CF, but there are now multiple randomized trials using genetic modifying medications that are showing great promise for future treatment. One particular CF gene mutation, G511D, now has an FDA-accepted medication for treatment, and patients receiving this medication have had normalization of sweat chloride testing and substantial improvements in nutrition and lung function.
