Failure to thrive: practice essentials in primary care

There are multiple definitions for what we refer to clinically as ‘failure to thrive’ in babies and young children, but usually it is established when a child’s weight is below the third percentile or where there is a decrease in weight of more than two major percentile lines on the growth chart. 

13 Aug 2021

Dr Amit Saha

It’s important to note that infants show considerable variability in their early weeks, with five per cent shifting up or down two intercentile spaces between birth and six weeks of age. 

‘Failure to thrive’ is usually caused by the following factors:

  • inadequate intake of food, through fussy eating or a poor diet
  • impaired absorption of nutrients (where there could be the presence of mucosal disorders like coeliac disease)
  • excessive energy expenditure (where there could be underlying chronic disease)
  • excessive losses (eg; where a child might be experiencing chronic diarrhoea).

Assessment for ‘failure to thrive’

A GP assessment to determine ‘failure to thrive’ is vital to recognise and address these issues early, to prevent developmental or cognitive delays in a child. It is recommended that assessments for ‘failure to thrive’ include the following:

1. Medical history and physical examination to exclude red flag signs and symptoms suggestive of an underlying medical cause. Signs and symptoms to observe include:

  • dysmorphic features
  • edema 
  • hair colour/texture change
  • heart murmur
  • hepatomegaly
  • altered mental status
  • skin rashes
  • wasting
  • poor parent-child interaction

2. Dietary history to assess adequate calorie intake.

3. Assessment for possible underlying emotional and/or psychosocial issues.

Management options for GPs

If ‘failure to thrive’ is suspected, the following management options are available to GPs before a referral is made to a specialist:

1. Dietitian referral and input - with a view to assess and optimise calorie intake.

2. Consider urine, stool and blood investigations as clinically indicated, including:

  • urine for microscopy, culture and sensitivity
  • stool infection screen to look for: fat globules, fatty acid crystals, reducing substances, alpha 1 antitrypsin, faecal elastase (in presence of chronic diarrhoea)
  • bloods: full blood count, urea and creatinine, electrolytes, liver function tests, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), glucose, thyroid function tests, coeliac screen, immunoglobulins and nutritional bloods (ie; calcium, magnesium, phosphate, B12, folate, vitamin D, zinc and iron studies)

3. Continue periodic surveillance and monitoring of growth parameters.

When to refer to a gastroenterologist

Referral should be made to a gastroenterologist in the presence of red flags (as indicated above), where there is suboptimal weight gain despite good calorie intake or when there is a suspected underlying medical cause. 

Once the child is referred, a gastroenterologist will consider:

  • Other investigations including gastroscopy and/or colonoscopy to assess for mucosal and absorption issues.
  • Collaborative immunology, allergy, metabolic and genetics workup, as clinically indicated
  • Multidisciplinary input and need for hospitalisation for observed feeding, nutritional rehabilitation and monitoring for re-feeding syndrome.
  • Need for parenteral nutrition, in severe cases.
  • Long term surveillance for optimal growth and cognitive development.


Dr Amit Saha - paediatric gastroenterologist at St John of God Murdoch and Midland Public and Private and Hospitals

Dr Amit Saha is a paediatric gastroenterologist. He conducts paediatric endoscopies in children of all ages as part of his paediatric gastroenterology services. Referral information for Dr Saha can be found on his specialist profile.