Failure to thrive is a term use to describe babies and young children under two years of age who are lighter than 97% of children their age, and who do not put on weight or develop at the expected rate.
Obviously the most common cause is neglect and starvation. Sometimes this can be difficult for doctors to detect, as it is only when the child is hospitalised or information is given by friends or relatives that this problem becomes apparent.
Persistent infection, particularly of the urine, is another common cause. Infections may be low grade and not apparent, urine infections may have no symptoms in young children, and collection of urine samples is difficult, making them hard to detect.
Infestations of the gut with various worms and parasites must be excluded by examination of a sample of faeces in a laboratory.
Genetic factors must also be considered. If both parents are very small, then the child may be also be small but completely healthy.
A wide range of uncommon diseases can cause failure to thrive. If one of the common causes above cannot be found, it may be necessary to undertake extensive investigations to find a long term disease that is affecting the child’s growth. Examples include:
- diabetes (rare under two years),
- pyloric stenosis (narrowing of the outlet of the stomach),
- Down syndrome,
- Turner syndrome (girls born with only one X chromosome instead of two),
- Fanconi syndrome (failure of the kidneys),
- major heart valve and artery abnormalities (e.g. Fallot tetralogy, patent ductus arteriosus),
- cystic fibrosis (failure of the glands throughout the body),
- coeliac disease (intolerance to gluten in flour),
- failure of any of the body’s major hormone producing glands (e.g. thyroid gland, pituitary gland, adrenal glands and parathyroid glands),
- a diet deficient in iron or other essential nutrients.
Numerous other rare congenital and acquired conditions may also cause failure to thrive.