Insulin-like Growth Disorder Factor-1 Deficiency (IGFD)

Children with short stature may have low levels of the hormones associated with normal growth. Children with low levels of growth hormone (GH) are said to have growth hormone deficiency (GHD) and this results in growth failure (see the Growth Hormone Deficiency page). GHD leads to low levels of insulin-like growth factor-1 (IGF-1), a hormone made primarily in the liver. IGF-1 regulates the growth-promoting effects of GH by acting on ‘target’ body tissues such as the growth plates of the bones.

Some children have growth failure, despite normal or even high levels of GH. In some of these children we find abnormally low levels of IGF-1 and this condition is called Primary Insulin-like Growth Factor Deficiency (PIGFD). Here the term ‘primary’ means that no secondary cause of low IGF-1 levels (e.g. a chronic medical illness) can be identified.

Why does it occur?

Severe primary IGF-1 deficiency (SPIGFD) is a medical term used when IGF-1 levels are extremely low or undetectable in the blood. The classical (most well recognised) form of SPIGFD is a genetic condition called Laron syndrome. Patients with Laron syndrome have an abnormal growth hormone receptor (GHR) which does not function properly. The GHR is vital for normal growth, as it recognises and binds GH, triggering release of IGF-1 and stimulating growth in the individual cells of the body. In Laron, the abnormal GHR makes patients resistant to the effects of GH and as a result, the IGF-1 levels are low or undetectable. A number of other genetic abnormalities in the GH – IGF-1 pathway are known to cause SPIGFD and short stature.

How is PIGF-1 Deficiency diagnosed?

A diagnosis of Primary Insulin-like Growth Factor Deficiency (IGFD) is made by identifying:

• Growth failure or short stature
• Normal growth hormone production
• Low levels of IGF-1
• No other underlying disease or causes of poor growth e.g. chronic diseases, poor nutrition

When all of these criteria are met, a doctor may diagnose IGFD. IGFD may be divided into moderate and severe forms based on how short the child is and how low the IGF-1 levels are relative to other children of the same age. As some children with PIGFD have an underlying abnormality in their genes, genetic testing is sometimes offered as part of the initial investigations.

Signs & Symptoms

The primary symptom of IGFD is short stature at below ‘normal’ levels. Additionally a child with IGFD may suffer from tiredness and a lack of energy. The short stature will make them appear younger than their peers but it will not impact on their intellectual abilities.