Failure to Thrive, Part 1

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Michelle Thompson, MD, and Solomon Behar, MD discuss the diagnosis of and evaluation of a child with failure to thrive.

Pearls:

• Failure to thrive is a weight for age that is less than the third percentile, a weight for height that is below the fifth percentile, or a weight that decreases two or more major percentile lines.
• There are generally three reasons kids fail to thrive; they do not take enough calories in, they take enough calories in but they do not properly absorb the calories, or their metabolic needs outweigh the amount of calories that they are taking in.
• The majority of the workup is in the history and physical exam.

• What is failure to thrive (FTT)? Failure to thrive is the inavailability or unavailability of usable calories. Usually, it is in a child who is less than 2 years of age who meets certain criteria. The three most common criteria used clinically are: 1) a weight for age that is less than the third percentile, 2) a weight for height that is below the fifth percentile, and 3) a weight that decreases two or more major percentile lines.
• When babies are first born, they can be large and then at the two or four month visit they are crossing a number of growth percentage lines. How does this type of weight loss play into it? There is wiggle room for adjustment for large babies, preemie babies and babies with intrauterine growth restriction or IUGR.  When we talk about an initially large baby in the first months of life 0-3,  weight is generally more representative of the placental health and pregnancy factors.
• For a premature baby who is really tiny and starts out in the third percentile, how do you make the diagnosis of FTT?  We continue to plot preemie infants on a preemie growth chart until about two years of age.  You have to look at the velocity of the child's weight and then take into consideration the height as well.  A child who is running below the third percentile consistently, but is tracking along a line below the third percentile, i.e. normal growth velocity, and the weight for height is demonstrating that he is on the normal curve, then genetically the baby may be programmed to be that way. That is not necessarily going to be defined as FTT.
• What about a child with a syndrome like Down syndrome who has their own growth curve? Can you do the same thing for them? Plotting along the available growth curves for those special populations when we have growth curves available is very important. To have a diagnosis of failure to thrive, you really do need to see the weight falling off the curve and dropping through percentiles. These days most children who have failure to thrive tend to have some combination of an underlying physical or developmental issue combined with environmental or social factors.
• Why do kids fail to thrive? There are generally three reasons kids fail to thrive.
• • 1) The children are not getting enough calories
  • 2)The children are getting enough calories, but they are not able to absorb the calories
  • 3) The children have excess caloric expenditure because their metabolic needs outweigh the amount of calories that they are taking in.  This increased metabolic demand can be seen in  chronic hypoxemia, chronic lung disease, and congenital heart disease
• Let's say you have a patient who comes to your clinic and he has dropped a few percentiles on his growth chart. Where do we start? Try to identify any patterns to the way the child is growing or not growing.  Look at the timing of the concern in the growth. For instance, if a child starts falling off the growth curve at an age when certain foods were introduced, then we might think about some sort of food allergy or intolerance, like celiac disease or a fructose intolerance.
• In what situation does the weight start falling off, but the height and head circumference are preserved? That means the child has inadequate nutrition. You can actually reach a point with malnutrition where the height and head circumference suffer as well, but typically you will see the weight drop off first, followed by the length or height and then ultimately if the child is not evaluated and is not treated, then the head circumference can fall as well.
• What if the weight and height and head circumference are all falling off together? What is that indicative of? If everything is falling off then typically I am thinking something like a central nervous system (CNS) abnormality or some sort of in utero insult. I go back to the birth parameters. Perhaps this child was IUGR.  Maybe there was a in utero congenital infection.
• What is the work up for FTT? I want to emphasize that the majority of the workup is in the history and physical exam. There will be some screening labs as well, but these are guided by the history and exam.
• • Start off very general with dietary questions. "Tell about meal times in your home". You really want to ask about what the child is eating and how much the child is eating.  Sometimes that means having the family actually do a meal by meal food recall or giving them a chart and having them fill that out at home and bring it back to the next visit.
  • I want to know how the meal times are organized and if the meal times are scheduled.  Is the child seated at the table with other family members for meals? Are there distractions like TV? Is the child allowed to graze in between meals and play and eat at the same time? What do they drink in between meals? This is where a lot of the over consumption of juice and milk comes in.  Are there certain textures or types of foods that the child avoids? For example, some children with autism may avoid certain textures.  Or you may have a child who has an inborn error of metabolism that will basically avoid all proteins because every time he eats too much protein, he will start to throw up and feel sick.
• What other aspects of the medical history are  really important to ask about?
• • You definitely you want to go back and get a good prenatal history and a perinatal history.
  • • Are there any concerns for in utero substance exposure, drugs or alcohol?
    • Was there any prenatal stress? Was there any perinatal hypoxia or possibility for that?
    • Is there a history of prematurity? What was the baby's size at birth?
  • Going through your systems review, you want to make sure that you are asking about any signs or symptoms that may be related to feeding intolerance.
  • • Is there a history of unexplained weight loss in the past?
    • Is the child displaying any vomiting?
    • Is there any evidence of choking with their feeds or difficulty swallowing?
    • Do they have any respiratory symptoms that are chronic or recurrent?
    • Is the child complaining constantly of abdominal pain? Do they have constipation or diarrhea?
  • Urinary symptoms are important to ask about as well. You may find a kid producing too little or too much urine, which could be indicative of chronic renal disease or diabetes respectively. Unusual urine odors could be suggestive of an inborn error of metabolism.
  • A history of recurrent infections is another important detail to inquire about. Too many episodes of otitis media or pneumonias that aren't clearing could be suggestive of an immune deficiency.
  • A history of rashes could be significant. A persistent rash could go along with any type of atopic history or allergic type history. Some of the immune problems are also associated with rashes.
• Moving onto the physical exam what are you looking for that is going to tip you off and give you that diagnosis of FTT?
• • Start with  growth parameters and get a head circumference, even if you feel the child is older than the age where you normally would check a head circumference.
  • Take a good look at dentition and examine the teeth  for any evidence of cavities. Actually watch the child eat something. If you cannot, then setting them up to be observed by a feeding specialist or occupational therapist is helpful.
  • Examine the neck to see if there is a goiter or any abnormalities of the thyroid gland that we can feel. We want to evaluate for lymphadenopathy that maybe an indication of a chronic condition, oncologic condition or infection.
  • Thoroughly examine  the heart, looking for any signs of congenital heart problems, listening for murmurs and extra heart sounds, and examining the pulses.
  • Listen to the lungs. A child who is constantly wheezing or has adventitious lung sounds may have something  like cystic fibrosis or some other chronic respiratory issue.
  • A thorough abdominal exam is important to check for masses and organomegaly. Checking for stool retention could indicate constipation or poor motility.
  • Look around the anal area, looking for skin tags, fissures, or other signs of constipation may suggest some underlying gastrointestinal pathology.
  • The skin exam is important as well.  Look for rashes or hypo- or hyperpigmented lesions that may be a sign of a genetic disease.
  • On the neurological exam, look for any subtle signs of cerebral palsy or any kind of coordination issue involving mouth movements, chewing, or swallowing.
• If the history and the exam do not reveal the cause of FTT, what sort of preliminary lab tests do you do? At that point Thompson does a few preliminary labs with the understanding that sometimes this is going to be very low yield. Some of this testing may clue me into the sequelae of the nutritional issues that the child is having and every once in awhile may lead to the diagnosis.
• • Start with a complete blood count (CBC). This can be  helpful especially in  looking at the hemoglobin and the indices for any indication of a nutritional anemia. We look for a microcytosis for iron deficiency or a  macrocytosis indicating a potential  vitamin B12 or a folate issue, especially if the child is very restrictive in their diet.
  • Order a chemistry panel, specifically looking at the creatinine, and a urinalysis looking at the pH and the specific gravity. Make sure the child can properly concentrate her urine and can screen for renal tubular acidosis.
  • Get an erythrocyte sedimentation rate (ESR) which is non-specific, but may help point to an underlying inflammatory condition.
  • Consider  placement of  a PPD skin test  if there is concern for tuberculosis exposure or check a lead level if there are any other developmental concerns. Screen for thyroid disease with a thyroid stimulating hormone (TSH) level.
• How do you decide to admit a child for failure to thrive? If there is concern for the child's immediate safety, admit the child to the hospital. For example, if we have uncovered that there is domestic violence or if there are signs of physical abuse, then  admit the child. If there is dehydration and we are at the stage where the child clinically does not seem like he will be able to keep up with at least the minimum of his fluid requirements, then admit to the hospital. If there has been a patient that is being followed and we have made interventions that have not resulted in appropriate weight gain, then consider  admission  to the hospital to expedite further work up. Another reason to admit a child to the hospital for failure to thrive would be a sudden acute weight loss or an excessive amount of weight loss.
• What are we doing once the child is in the hospital? As an inpatient, usually the expedited workup is engaging a multidisciplinary team to work together.  Sometimes that requires direct feeding observation by speech or occupational therapists. The therapists may suggest additional work up such as a modified barium swallow study. Dieticians can help us ramp up the calories for some of these kids who have really not had adequate nutrition for prolonged period of time.
• Is there any imaging that is routinely ordered? No, not really. This is going to be a case by case basis and guided by history and physical.
• Is there a definite connection between failure to thrive and parental mental health? Yes, this has  been described.  The mental health of whoever is responsible for spending time with the child during the day and feeding him will play a role. The caretaker's own experience with feeding and nutrition even in their childhood can come into play.  Addressing issues related to the stressors and the mental health of the caretakers and providing resources for that are really important. One of the examples that Thompson uses is the child who grazes at the breast all day long. That is a source of comfort for the infant and also the mother who maybe tackling her own stressors. Putting the baby to the breast is a way for her to feel more comforted. The baby is basically just grazing all day and fails to thrive because she is not getting any other nutrition.

What are the common things pediatricians should be doing in their offices before referring their patients either to the ER or to the hospital to get admitted for a FTT workup? Frequent follow up visits,, a really thorough history and a good physical exam. Your main goal in that very first visit is to determine if the child is in danger right now. If he is not, then you can do a history and a full physical and bring the child back. It is really over the course of more than one visit that you are going to get to the core of what the issues are and the interplay between those issues.