Growth hormone (GH) acts directly or indirectly on the growth of organs and tissues of the body. The secretion of this hormone depends on a gland located at the base of the brain, called the pituitary gland, whose function in turn depends on the hypothalamus, the regulatory organ par excellence, thanks to the production and release of the stimulating factor of growth hormone (GHRH) and of somatostatin, which acts as an inhibitor.
The pituitary gland has two parts: anterior lobe or adenohypophysis and posterior lobe or neurohypophysis. Each one makes different hormones and therefore has different functions. The growth hormone is produced by Anterior lobe or adenohypophysis.
It also depends on factors such as sleep , body temperature and exercise. Growth hormone deficiency is a condition of congenital or acquired nature that is characterized by the total or partial absence of said hormone in plasma. It occurs when there is a failure in the pituitary gland, in the hypothalamus or in the pathway that connects the hypothalamus to the pituitary gland.
Causes of growth hormone deficiency
The most frequent causes of GH deficiency are idiopathic. The anomalies of the synthesis, secretion and activity of GH are usually sporadic and heterogeneous, including genetic syndromes with a molecular basis or not (3% of children have a brother with the same deficit, being more frequent in males), malformative causes, alterations in embryonic development, traumatisms, hypoxic processes, infections, tumors of the hypothalamic-pituitary or cerebral region and their treatments with surgery or radiotherapy, and peripheral insensitivity to GH.
GH deficiency can be associated with other hormonal deficits of pituitary origin, especially sex hormones, whose diagnosis and treatment is usually not carried out until puberty , which is when it is detected. There may also be a deficit of the stimulating hormones of the thyroid gland of the adrenal cortex, although less frequently.
Symptoms of growth hormone deficiency
Children with a congenital deficit of GH have weight and height in the normal range at birth. Prolonged neonatal jaundice is common (50% of cases). Hypoglycemia can occur in the first 4 years of life. The size is usually affected from the first 3-6 months of life, so that after two years it can be found in the 3rd percentile or below it. The growth rate is slow, lower than the 25th percentile.
Bone maturation is delayed 1-4 years in relation to chronological age. Without treatment, the pubertal growth spurt is usually delayed even up to 18-20 years. Intelligence is normal, but it is common to find signs of a certain immaturity and difficulty of adaptation to the social environment, secondary to parental protectionism and low self-esteem due to its low size. In the acquired forms, it initially show normal growth, slowing or stopping their growth curve later. Regardless of the etiology, they usually have common physical characteristics, but not pathognomonic. They have harmonic measures, cephalic perimeter appropriate to the age, delayed closure of the fontanelles and slow-growing hair.
The face characteristics are described as doll face. It is small with bulging forehead, flat nasal root and altered dentition. They may have a high-pitched, slightly overweight voice, little muscled limbs with a graceful appearance, and small hands and feet. In some children growth retardation is the only symptom, so it is convenient to explore the secretion of GH in all patients with growth retardation of unknown etiology.
Diagnosis of growth hormone deficiency
It is based on clinical, endocrinological studies of GH secretion, radiological studies that contribute to the topographic and morphological diagnosis and genetic studies, by means of molecular biology techniques. Normal levels of GH are fluctuating. This hormone is released in peaks. There are between 6-9 peaks in the day, from 10 to 20 minutes in length. Especially the release occurs during sleep. To measure GH levels we can make frequent determinations throughout the day or cause a peak release. There are several provocative tests with pharmacological stimulation, such as the insulin hypoglycemia test, the glucagon test (these tests alter blood glucose levels), clonidine or arginine test .
These tests may indicate that there is growth hormone deficiency when the GH values are less than 10 ng / ml. It is considered partial deficit if the response is between 5-10 ng / ml and total if it is less than 5 ng / ml. The response to the tests varies according to the age or pubertal period. The determination of growth factors (IGF-I), and their transporter protein, IGFBP-3 , can help in the diagnosis.
Treatment of growth hormone deficiency
The goal of treatment in these children is to increase the growth rate and adult height. The availability of large amounts of GH due to its obtaining by recombinant DNA, has allowed better knowledge of its metabolic effects and the demonstration that not only stimulates growth in children who have GH deficiency, but also in those who have short stature and apparently normal GH. Treatment should be initiated early once the diagnosis of certainty has been established. The doses used range from 0.025-0.050 mg / kg / day. They are adjusted individually according to the response and IGF-I and IGFBP-3 levels. It is administered subcutaneously before bedtime. You can learn more about it at https://hghtherapydoctor.us/sermorelin-therapy/
At the end of the growth a diagnostic re-evaluation is performed and if the GH deficit persists, the treatment should continue in adult life although at lower doses. Side effects are very scarce. Some cases of alteration of the femoral head (epiphysiolysis), carpal tunnel syndrome, secondary hypothyroidism, lipodystrophy at the injection site, development of anti-GH antibodies, hypertension, and carbohydrate intolerance have been described. During the treatment, control tests are carried out to detect any side effect and to be able to treat it adequately. A causal relationship between the development of leukemia and other malignant processes has not been demonstrated.