Failure to Thrive – Differential Diagnosis

A child may present with failure to thrive and not gaining appropriate weight for his age. There are a number of different factors responsible for it and a doctor should consider the following differentials in his mind.

Inadequate Intake
May result from a swallowing problem, formula mixing error, lack of access to formula or other foods due to limited finances, inappropriate substitution of other liquids ( eg juices ) for formula or neglect.

Excessive losses due to Diarrhea
Consider infectious agents ( bacterial, giardia ), HIV, cystic fibrosis or inflammation due to food allergies.

Increased Needs
It may be due to hyper metabolic states or disease that cause increased work of breathing. Consider cystic fibrosis, hyperthyroidism and cardiac disease.

Metabolic or Genetic Abnormalities
Consider inborn errors of metabolism and chromosomal abnormalities.