Isolated growth hormone deficiency (IGHD) is a rare

congenital disorder A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

characterized by

growth hormone deficiency Growth hormone deficiency (GHD), or hyposomatotropism, is a medical condition resulting from not enough growth hormone (GH). Generally the most noticeable symptom is that an individual attains a short height. Newborns may also present low blood ...

and

postnatal The postpartum (or postnatal) period begins after childbirth and is typically considered to last for six to eight weeks. There are three distinct phases of the postnatal period; the acute phase, lasting for six to twelve hours after birth; the ...

growth failure Failure to thrive (FTT), also known as weight faltering or faltering growth, indicates insufficient weight gain or absence of appropriate physical growth in children. FTT is usually defined in terms of weight, and can be evaluated either by a low ...

. It is divided into four subtypes that vary in terms of cause and clinical presentation. They include IGHD IA (autosomal recessive, absent GH), IGHD IB (autosomal recessive, diminished GH), IGHD II (autosomal dominant, diminished GH), and IGHD III (X-linked, diminished GH).

Signs and symptoms

Babies diagnosed with type IA are shorter than average at birth, which is a clear sign of

Short stature Short stature refers to a height of a human which is below typical. Whether a person is considered short depends on the context. Because of the lack of preciseness, there is often disagreement about the degree of shortness that should be called ...

is a characteristic of type IB, yet this development failure is usually not as severe as in type IA. People with type IB typically exhibit

in their early to mid-childhood years. Individuals suffering with isolated growth hormone deficiency type II exhibit variable degrees of short height and extremely low

growth hormone Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in ...

levels. These people typically exhibit

in their early to mid-childhood years. Similar to type II isolated growth hormone deficiency, type III is characterized by extremely low growth hormone levels and variable degrees of short height in the affected individuals. Type III growth failure typically manifests in early to mid-childhood. Individuals who have type III may also be more susceptible to infections and have a compromised

immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...

Causes

While the majority of isolated growth hormone deficiency cases are sporadic and assumed to be caused by hypothalamic or

pituitary The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans, the pituitary gland is located at the base of the brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus control much of th ...

injuries in utero, during or after birth, anatomic abnormalities are discovered in just 12% of such patients who undergo

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

(MRI). Many children with isolated growth hormone deficiency are known as having idiopathic growth hormone deficiency or idiopathic isolated growth hormone deficiency since in most cases, there is no known etiology for the condition.

Genetics

Genes encoding

( GH1) or the growth-hormone-releasing hormone receptor (GHRHR) have been linked to the pathogenesis of isolated growth hormone insufficiency. However, there have not yet been any reports of GHRH mutations. Rarely, heterozygous mutations in SOX3 or HESX13 might cause an isolated growth hormone deficit.

Diagnosis

The diagnosis of growth hormone deficiency is a multi-step procedure that involves pituitary

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

, biochemical testing (growth hormone stimulation tests and measurement of

IGF-1 Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in molecular structure to insulin which plays an important role in childhood growth, and has anabolic effects in adults. In the 1950s IGF-1 was called " sulfa ...

IGFBP3 Insulin-like growth factor-binding protein 3, also known as IGFBP-3, is a protein that in humans is encoded by the ''IGFBP3'' gene. IGFBP-3 is one of six insulin-like growth factor-binding protein, IGF binding proteins (IGFBP1, IGFBP-1 to IGFBP6, ...

), clinical and auxological examination, and genetic test results.

Classification

Four different forms of familial isolated growth hormone deficiency have been identified: X-linked recessive (type III), autosomal dominant (type II), and autosomal recessive (type IA and IB).

References

External links

{{Pituitary disease Growth hormones Endocrine-related cutaneous conditions Growth disorders Pituitary disorders