Pituitary dwarfism

How is it produced?

The growth hormone (GH) is synthesized in the gland. This hormone acts as growth stimulator by stimulating other substances (such as somatomedins or IGF-I) that act on the multiple phenomena involved in the growth of all organs and tissues. So the GH deficiency in childhood leads to short stature normal in adulthood, for this reason it is called pituitary dwarfism or short stature of pituitary origin. In the adult, the lack of this hormone does not condition any alteration in the individual's size. The GH hormone is regulated (stimulated) by a hormone made by the hypothalamus, GHRH. The causes that can originate a defect in the manufacture and function of growth hormone can arise from a lack of the secretion of GH or its stimulating hormone, GHRH.

What are your causes

The causes capable of causing a deficit in GH secretion and ultimately dwarfism are very diverse. Among them we have:

• Genetics: developmental defects causing a pituitary deficit (pituitary dysgenesis).
• Alterations genetics that inactivate the GH receptor gene. In these cases, hormone secretion is normal, but GH is unable to carry out its biological action.
• Tumors: they are the most frequent cause, and in particular craniopharyngioma, which can lead to hypopituitarism.
• Trauma during childbirth, from obstetric maneuvers.
• Infections.
• over the area of ​​the pituitary gland and hypothalamus.

Sometimes the pituitary production of GH is normal, even being elevated, but there is a peripheral resistance of the receptors to the action of GH, this is what is known as Laron syndrome.

Symptoms

The clinical manifestations vary depending on the cause and the age at which GH deficiencies develop.

• In the neonatal period and early childhood, the male may have a decrease in the size of the penis (micropenis) and absence of testicles in the scrotal sac (cryptorchidism) together with episodes of decreased blood glucose. Similar problems occur in women, except for genital abnormalities. The presence of a certain prevalence of obesity in the trunk is typical.
• In second childhood and in the period around puberty: there is an evident growth retardation, the skin is pale-yellowish and a boyish look "doll-like" (broad, domed forehead, sunken nasal root, and rounded cheeks). The voice is high-pitched and squeaky, and teething is often delayed. The bone age is always very delayed and as a consequence there will be a short stature. If he deficit is congenital manifestations are usually from the 6-12 months, with height and weight at birth being normal. If he deficit is acquired and non-congenital there will be a growth arrest after a period of normal growth.
• In the peripuberal period the slowing down of the growth rate is evident. Pubertal signs do not appear. There is a significant delay in bone maturation, especially in men.

Diagnosis

In the initial stages of life, it will be suspected by the clinic, being the parents who appreciate the growth retardation, especially marked from two years. In case of GH deficiency in later ages, it is initially normal. When the clinical features suggest dwarfism of pituitary origin, the determination of IGF-I is a useful test. GH is not determined in the blood since a single random measurement does not allow the diagnosis or exclusion of the disease, nor is it directly proportional to its severity. For the diagnosis we must ask for the blood concentration of IGF-I, which will be diminished. A left hand x-ray to study bone age, which will be behind the chronological age. The will be the best imaging technique to assess the sella turcica and the pituitary.

Treatment

Treatment consists of hormone replacement with GH. The response is good after the continuous administration of GH, observing that the increase in growth is accompanied by a decrease in body fat and an increase in muscle mass. The youngest show an increase in head circumference. The best route of GH administration is the subcutaneous route in daily injection. Replacement treatment with synthetic GH in adults is accepted today as it improves quality of life, lowers the risk of osteoporosis and improves cardiovascular parameters and lipid metabolism.