Hyperphagic Short Stature Syndrome

Hyperphagic short stature is a behavioural disease associated with linear growth failure, secondary to growth hormone insufficiency. The syndrome was first described in the 1960s when it was grouped under the term psychosocial short stature.^1,2
Hyperphagia may be defined as an excessive and abnormal appetite for food. This is accompanied by an apparent lack of satiety and frequently eating to the point of vomiting or abdominal pain.

The syndrome is rare and part of a small group of behavioural phenotypes associated with a physiological mechanism.

Risk Factors

• Hyperphagic short stature is strongly associated with poor environmental and social conditions.
• The most common source of psychosocial stress for children with the syndrome is intra-familial abuse.³ Familial studies suggest a genetic predisposition to the disease but a specific genetic defect has not been demonstrated.⁴
• It has an increased prevalence amongst children in foster care.⁵

Symptoms

Commonly reported during infancy are:

• Feeding problems
• Poor muscle tone
• Failure to thrive

Hyperphagia does not occur until the third year and is associated with polydipsia. Symptoms of depression, sleep cycle disturbance and self injury, such as skin picking, also occur.

Signs

• The height for age is below the third centile, between 85% and 90% of expected height for age. Growth is often at a low normal rate parallel to the centile line. Head circumference is usually in proportion.
• Hyperphagic short stature is associated with learning disabilities.
• Affected children are frequently overactive and maintain a body mass index within the normal range despite over eating.
• There is often history of wandering around the home at night in search of food. Food is often hoarded, usually in the child's room.

Prader-Willi Syndrome; this is a congenital condition due to an anomaly at chromosome 15. It shares many of the characteristics of hyperphagic short stature. However, in contrast to hyperphagic short stature, Prader-Willi syndrome is associated with an obese body mass index, lethargy and more severe learning disabilities.

• Standard behavioural measures can be used to detect hyperphagia and polydipsia, the major characteristic behavioural features of hyperphagic short stature.
• The syndrome is also associated with growth hormone insufficiency.

• Hyperphagia and sleep disruption resolve rapidly if the childs living conditions are improved.
• This is associated with a rapid increase in growth hormone to normal levels.³
• If improvements are maintained, growth rates will also improve over a longer period of time.^1,2
• The psychosocial stress associated with and generated by hyperphagic short stature will require multidisciplinary support for the family and child.