See also: Acromegaly
Generality
Gigantism is the exaggerated statural growth of an individual compared to the reference population.
In Italy the average height in adulthood is around 175 cm for the male and 162 cm for the female.
Depending on the sources, gigantism is spoken of when the height exceeds by 15-20% the average height of the reference population (201-210 cm for the Italian adult male, 186-194 cm for the Italian adult female). Nevertheless, it is necessary to distinguish the cases of constitutional or hereditary gigantism from those of a pathological nature.
Causes
Pituitary giantism
Morbid gigantism can be caused by excessive secretion of hGH. In these very rare cases, we speak of pituitary gigantism, a syndrome often due to an adenoma of the pituitary gland.
The exaggerated release of this hormone during developmental age greatly accelerates the lengthening of long bones; subsequently, in the post-puberal phase the dimensions of the extremities increase considerably (see acromegaly).
Growth in height and puberty
The statural growth of an individual is allowed by the presence of small regions, called epiphyseal plates, interposed between the epiphysis and the diaphysis of long bones. These bone growth nuclei produce cells capable of continuously dividing and synthesizing new cartilage tissue, which is then ossified little by little.
The welding of the epiphyseal plates, which normally occurs around the 18th -20th year of age, marks the definitive halt of growth in height. Since this event is due to the chronic increase in the circulating proportion of sex hormones (in particular estrogen), it is not surprising that some forms of gigantism are typical of delayed puberty; in these cases we speak of eunuchoid gigantism, characterized by a disproportionate increase in the length of the lower limbs compared to the upper ones (eunuchs are castrated male subjects). Precocious puberty, on the other hand, is accompanied by a rapid pre-term growth, which nevertheless stops just as quickly, leading to a state deficit in adulthood. Puberty disorders are quite common even in pituitary gigantism.
Other forms of gigantism
Another form, called cerebral gigantism, is associated with the so-called Sotos syndrome, in which the circulating GH levels are normal; the children who are affected show excessive body growth during the first two or three years of life, with a notable increase in head circumference and delayed psychomotor development.
There are also excesses in the Marfan syndrome, a genetic disease (like the previous one) that affects the connective tissue, and in that of Klinefelter, in which high stature is associated with hypogonadism, gynecomastia and poor hair development.
