Background: Average height for adult men in Sweden is 181.5 cm and for women 166.8 cm (2008). Many factors affect body growth, among which age, genetic, hormonal, nutritional, health, and environmental factors are the most common, whereas abnormal growth hormone effect is a rare factor. Wide variations in growth development exist between different countries, and standards for age-dependent growth in one country cannot be applied to the population of another country. Growth Hormone is one of the six hormones secreted from the anterior lobe of the pituitary. It stimulates body growth throughout childhood by stimulating production of a growth factor, IGF-1, that acts on the growth zones of the long bones of the extremities. Increased production of estradiol during puberty (in men, normal steroid synthesis converts testosterone into estradiol) slowly closes the growth zones in the bones at the time of puberty and terminates growth. Therefore, the timing of puberty will have some effect on the final height of a person. Production of growth hormone in the pituitary decreases at the time of puberty, but it continues at a low level throughout life.
Symptoms: Short stature is defined as two standard deviations below the normal mean height for age in the population. There are several physiological causes of short stature, and low production of IGF-1 or growth hormone constitute only two of these causes. Puberty and estrogen production occurring early will terminate growth at a lower height than will puberty developing at a later age. Short stature may lead to a lower self confidence.
Diagnose: Short stature is diagnosed by inspecting recordings of several measurements of body height relative to age over a period of years. Growth curves are therefore kept for every school child. When the measurements fall below two standard deviations of the normal growth curve for the population, short stature is diagnosed. Measurements of IGF-1 or growth hormone in blood do not establish the diagnosis.
Treatment:Short stature due to abnormally low growth hormone effect can in some cases be treated with synthetic growth hormone injected subcutaneously two to three times a week until the end of puberty and the closure of growth zones. Even with some other causes of low growth, growth hormone treatment may be attempted.
Symptoms: Excessive body growth may be the result of pituitary tumors producing too much growth hormone before closure of the growth zones. After closure of the growth zones increased production of growth hormone will cause development of characteristic skeletal features. Delayed puberty both in females and males may keep the growth zones open at higher ages and may cause excessive body height. The major effect of excessive body height is psychological, due to the mental pressure of being different from one’s peers.
Diagnosis: Tall stature is defined as a body height more than two standard deviations above the normal mean height for age in the population and is diagnosed from inspection of the growth curve over time. The expected final height of a person may be calculated from the growth velocity. Development of the growth zones in the long bones in relation to chronological age is estimated by x-ray examination. Increased production of growth hormone is measured in blood samples. In rare cases boys have been diagnosed with genetically impaired conversion of testosterone to estrogen or with reduced sensitivity to estrogens as the causes of delayed closure of the growth zones and continued growth with otherwise normal male pubertal development.
Treatment: Estrogen treatment will bring about puberty and terminate the excessive growth in girls with delayed puberty, but may have mental side effects. In boys with continuing growth because of diminished estrogen effect the growth can theoretically be terminated with estrogen treatment, but may also cause undesirable side effects.