Failure to thrive

Published on 21/03/2015 by admin

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Last modified 22/04/2025

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Chapter 16 FAILURE TO THRIVE

Jonathan M. Wong and Timothy J. Horita

General Discussion

Failure to thrive (FTT) is a descriptive term and not a specific diagnosis. FTT is best defined as inadequate physical growth diagnosed by observation of growth over time using a standard growth chart. Most practitioners diagnose FTT when a child’s weight for age falls below the fifth percentile of the standard National Center for Health Statistics (NCHS) growth chart or if it crosses two major percentile lines.

Average birth weight for a term infant is 3.3 kg (7.27 lb). Weight declines as much as 10% in the first few days of life, probably as a result of loss of excess fluid. Birth weight should be regained within 2 weeks after birth. Breast-fed infants tend to regain birth weight a little later than bottle-fed infants. Term infants double their birth weight by age 4 months and triple their birth weight by age 12 months.

Term infants grow approximately 25 cm in length during the first year, 12.5 cm in the second year, and then slow down to about 5 to 6 cm per year between age 4 and the onset of puberty, at which time growth can increase up to 12 cm per year. Average head circumference is 35 cm at birth and increases rapidly to 47 cm by age 1 year. The rate of growth then slows, reaching an average of 55 cm by age 6 years.

Adjusted growth curves for different populations exist, including those for premature infants, Down syndrome, Turner syndrome, meningomyelocele, intrauterine growth retardation, low birth weight, and very low birth weight. While plotting growth charts for premature patients, a “corrected age” is used when using a standard growth curve. This corrected age is calculated by subtracting the number of weeks of prematurity from the postnatal age (gestational age). This corrected age should be continued with subsequent measurements because it may take an average of 18 months to catch up on head circumference, 24 months for weight, and 40 months for height.

Accurate measurements are essential to the interpretation of growth charts. Scales need to be calibrated regularly, and it helps to use the same machines, if possible, for consecutive measurements. Similarly, lengths should be measured carefully, and head circumference should be measured using standardized techniques.

As long as the patient is growing along a curve (albeit at a lower percentile), FTT should not be diagnosed. Growth variation in normal infants can confound the diagnosis of FTT. About 25% of children will shift their weight or height downward by more than 25 percentile points in the first 2 years of life. These children are falling to their genetic potential or demonstrating constitutional growth delay. After shifting downward, these infants grow at a normal rate along their new percentile and do not have FTT.

In the United States, reports from 1980 to 1989 indicate that FTT accounted for 1% to 5% of tertiary hospital admissions for infants younger than 1 year. This probably represents an underestimation, however, because most children with FTT are not admitted to the hospital. An estimated 10% of children in primary care settings show signs of FTT. In underdeveloped countries, FTT is more common, with malnutrition manifesting as FTT.

Ultimate physical growth may be decreased in children with FTT. Cognitive development is affected in children younger than 5 years who have FTT. Even with improvement of nutritional status, these deficits might not be completely reversed. Traditionally, it had been thought that nonorganic causes of FTT, such as neglect, resulted in more cognitive deficits than organic causes, such as gastrointestinal absorptive problems. In developing countries, malnutrition is a significant cause of mortality, whether directly or secondary to complications such as infection.

FTT can occur in all socioeconomic strata, although it is more frequent in families living in poverty. Studies indicate an increased incidence in children receiving Medicaid, children living in rural areas, and homeless children. Nonorganic FTT is more commonly reported in females than in males.

Causes of Failure to Thrive

Traditionally, FTT has been divided into organic and nonorganic causes. This distinction is not used as often because most children with FTT have mixed causes. A child with a medical disorder may develop feeding problems, which can cause family stress, which then further compounds the feeding problem. Nonorganic causes may also result from environmental factors, psychological factors, an abnormal interaction between the caregiver and child, or maternal rejection or neglect of the child. A malnourished mother or mother with an eating disorder may also result in a child having FTT. Likewise, family dysfunction, a difficult child, or poor parental feeding skills may lead to FTT.

More recently, the classification of FTT has been based on pathophysiology: inadequate caloric intake, inadequate absorption, excess metabolic demand, or defective utilization.

Inadequate Caloric Intake

Inadequate Absorption

Increased Metabolism

Chronic infection

• Human immunodeficiency virus (HIV)

• Other immunodeficiencies

Hyperthyroidism

Hypoxemia

• Chronic lung disease

• Congenital heart defects

Malignancy

Renal disease

Defective Utilization

Congenital infections

Diabetes mellitus

Genetic abnormalities (trisomies 21, 18, 13)

Metabolic disorders

• Amino acid disorders

• Lead poisoning

• Storage diseases

Peripartum drugs (alcohol, cocaine, tobacco)

Other Causes

Gastroesophageal reflux

Growth hormone deficiency

Hypopituitarism

Hypothyroidism

Prematurity

Key Historical Features

Lethargy, fatigue, or activity level below an age-appropriate level

Parental concern over poor feeding or weight gain

Abnormal voiding patterns, especially diarrhea

Prenatal history

• Maternal smoking or passive smoke exposure

• Maternal drug use

• Maternal alcohol consumption

• Medication use during pregnancy

• Illness or infection (meningitis, preeclampsia) during pregnancy

• Intrauterine growth retardation

Birth history

• Complications

• Prematurity

• Small for gestational age

Feeding history

• Frequency and duration of breastfeeding or formula feeding

• How formula is prepared

• Appropriate advancement of diet

• Types and amounts of solid food

• Context of parental-child dynamics during feedings

• Number of wet diapers and stools per day

• Coughing, choking, or breathing problems associated with feeding

• Significant vomiting after feedings

• Abdominal pain or distress following feedings

Past/current medical history, especially

• Developmental milestones

• Time of onset of puberty

• Chronic diarrhea

• Anemia

• Asthma

• Congenital heart disease

Family history

• Postpartum depression

• Short stature or FTT

• Cystic fibrosis or metabolic disorders

• Data on parents’ growth history

Social history

• Parental inexperience or inattention

• Care providers

• Siblings

• Living conditions

• Family financial situation

• Stressors

• Evidence of neglect

Lastly, the child’s developmental status should be ascertained at the time of the visit because children with FTT have a higher incidence of delays than the general population. Physicians should still be concerned about a child without developmental delays who is failing to thrive. FTT is primarily a growth disorder, not a developmental problem.

Key Physical Findings

Vital signs

Height, weight, and head circumference plotted on a growth curve and compared with previous measurements. A corrected age should be used for preterm infants. Charts for special populations should be used when appropriate.

General examination for dysmorphic features suggestive of a genetic disorder impeding growth or any evidence of underlying disease impairing growth

The general assessment should also evaluate for signs of wasting, as well as an assessment of the severity and possible effects of malnutrition

Head and neck examination for craniofacial abnormalities such as severe micrognathia, cleft lip, or cleft palate. The quality of tears and dryness of mucous membranes should be noted. The fontanelles should be evaluated to determine whether they are sunken

Cardiopulmonary examination for any evidence of cardiac or pulmonary disease

Abdominal examination for hepatomegaly or mass

Extremity examination for edema

Skin examination for rashes, skin turgor, or skin changes

Musculoskeletal and skin examination for any evidence of physical abuse

Genitourinary examination if sexual abuse is suspected

Neurologic examination for any mental status changes

Interaction between parent and child

Suggested Work-up

The laboratory assessment has limited value in determining the etiology of FTT. Occasionally, laboratory test results are unexpectedly abnormal, as in the case of chronic urinary tract infections (UTIs), chronic acidosis, renal failure, and blood dyscrasias. Only about 1% of the tests yield abnormal results leading to the cause of FTT.

Some studies advocate the following screening labs:

Complete blood cell count (CBC)	To evaluate for anemia, infection, or malnutrition (decreased total lymphoryte count)
Electrolytes, blood urea nitrogen, (BUN), and creatinine	To evaluate for renal disease
Serum bicarbonate	To evaluate for chronic acidosis
Fasting glucose	To evaluate for diabetes
Liver function tests, including total protein and albumin	To evaluate for liver disease and malnutrition
Serum prealbumin	To evaluate nutritional status
Iron studies (ferritin, iron, total iron binding capacity [TIBC])	To evaluate for iron deficiency
Urinalysis and urine culture	To evaluate for UTI

Additional Work-up

HIV test	If HIV infection or acquired immune deficiency syndrome (AIDS) is suspected
Sweat chloride test	If cystic fibrosis is suspected
Thyroid stimulating hormone (TSH)	If hyper- or hypothyroidism is suspected
Lead level	If lead poisoning is suspected
Stool studies for ova and parasites	If intestinal infection is suspected
Fecal fat analysis	If malabsorption is suspected
Serum immunoglobulins	If an immune deficiency is suspected
Purified protein derivative (PPD)	If tuberculosis is suspected
Selected radiologic studies	If abuse or infection is suspected
Serum insulin-like growth factor	If growth hormone deficiency is suspected
Tissue transglutaminase antibody, gliadin antibody, and endomesial antibody	If celiac disease is suspected
Radiologic evaluation for bone age	To help distinguish genetic short stature from constitutional delay of growth
Small intestine biopsy	To confirm a diagnosis of celiac disease