Endocrine Gland Disorders
The two main endocrine disorders causing short stature are:
- Growth Hormone Deficiency
- Thyroid Deficiency
Growth Hormone Deficiency
If MPHD (see definition below) at birth. If GHD, diagnosis is possible by 18 months. Around 80% of GHD cases should be diagnosed by school entry.
Growth hormone (GH) replacement therapy
Growth Hormone Deficiency (GHD) generally occurs when the pituitary gland cannot produce enough growth hormone (GH) for the patient to grow normally.
GHD does not affect intrauterine growth, at least not to an extent measurable by birth weight or length, but from around the age of two, or occasionally from birth, growth is slower than normal. Most cases of growth hormone deficiency are idiopathic or unknown origin. This seems to occur in around 1 in 3800 births.
In some cases GHD may be hereditary. About 3% of children with GHD have siblings with the disorder. In a very few families, one of the parents is affected. The deficiency is two to three times more common in boys than in girls, although we don’t know why.
Children with GHD are small with normal skeletal proportions, facial appearance and intelligence. They tend to be overweight (although this reduces during GH treatment) and they often have a delayed bone age.
The diagnosis is confirmed by measuring the level of growth hormone production in response to a stimulation test, which generally requires a morning in hospital. The deficiency may be of growth hormone only, although other pituitary hormones may also be affected (MPHD).
The associated hormone deficiencies are:
- thyroid-stimulating hormone (TSH)
- the gonadotrophins - follicle stimulating hormone (FSH) and lutenising hormone (LH)
- adrenal-stimulating hormone (ACTH) is much less frequently involved, but the deficiency of this hormone is extremely important to detect.
If there is a deficiency of TSH, thyroxine is given, and if gonadotrophin deficiency becomes apparent at the time of puberty (which is usually late in growth hormone deficient children), the sex hormones also have to be given to initiate sexual maturation.
The treatment of growth hormone deficiency has been recognised since the first patient was given human growth hormone by Raben in 1958 in Boston, USA, although since October 1985, biosynthetic growth hormone has replaced the pituitary derived hormone in the UK. Provided treatment is started reasonably early on (at least before the age of six) the results are nearly always excellent (even at later stages results are sometimes spectacular).
Catch-up-growth occurs following initial treatment and so a normal growth rate is usually maintained.
Adults with growth hormone deficiency may require growth hormone treatment for metabolic reasons after they have stopped growing. The daily doses are usually much lower than those given to children. The lack of growth hormone may contribute to symptoms of general tiredness, weakness and weak bones (osteoporosis). Growth hormone is an approved treatment for adult GHD.
Every child who has had oncology treatment is a possible candidate for growth hormone.
Growth hormone deficiency can also occur following damage to the area of the brain controlling the pituitary gland, the pituitary itself, or both. Some tumours are benign, i.e. non-cancerous, and the most common tumour in the pituitary region is called a craniopharyngioma. This is not technically a brain tumour, but part of a piece of mouth epithelium (the lining of the mouth) pinched off and left behind during the development of a baby while still in the womb.
A craniopharyngioma can be identified by a skull x-ray, MRI or by computer assisted tomography (CT) of the brain. Craniophyaryngioma’s are usually removable through surgery. Occasionally, they reoccur, but can be removed again.
A child with a pituitary tumour sometimes sees a doctor just for their short stature, but more usually the symptoms are neurological e.g. headaches, nausea, affected vision.
Treatment may involve radiotherapy and / or surgical removal of the tumour after which the child may develop a combination of pituitary hormone deficiencies.
Most, though not all, have growth hormone deficiency. They are treated with growth hormone, often in conjunction with thyroxine, cortisol (hydrocortisone) and, at the time of puberty, gonadotrophins or sex hormones. Equally such children may need replacement of the posterior pituitary hormone, vasopressin - to restore a normal fluid balance in the body.
Congenital at birth or late onset at any age during childhood
Lack of thyroid gland secretion (thyroxine) may also stop normal growth, as all cells need a certain level of thyroid hormone to function properly. Hypothyroidism may start in utero, in which case brain development is affected, so diagnosis and treatment straight after birth are crucial. The condition can be diagnosed by measuring levels of thyroid hormone in the blood, now a routine screening test for all newborns.
Short stature is more usually caused by late onset of hypothyroidism, which starts during childhood, often subtly. Catch-up growth during thyroid hormone replacement treatment is marked but, unfortunately, rarely complete.
Typical Growth Chart for Idiopathic Hypothyroidism
Typical Growth Chart for Acquired Hypothyroidism
To NICE and Beyond: What's new with GH? (PDF)
NICE recommends somatropin to treat growth failure in children (PDF)