When discussing growth disorders, it is impossible to ignore the issues related to excessive growth, i.e. height exceeding the 97th percentile for a given population, gender and age. The reasons for the excessive growth are shown in Table 13.2.
Too much growth hormone leads to gigantism or acromegaly (G / A) depending on whether the epiphyseal gaps are open or closed. Gigantism affects children and acromegaly affects adults. In adolescents, a mixed picture is observed: a significant acceleration in the speed of growth, as well as features of acromegaly
The most common cause of excessive GH secretion are pituitary adenomas that produce only GH and mixed adenomas that produce, apart from GH, also: Prl, α-alpha and β-subunit, less frequently follitropin (FSH), lutropin (LH) or TSH. The source of GH may also be hyperplasia of the pituitary somatotropin cells and ectopic tumors: pancreas, lungs, ovaries or mammary glands. Another cause of G / A is excessive GHRH secretion by hypothalamic tumors, such as hamartoma, glioma, ganglioneuroma, and also by tumors located outside the CNS: bronchial or gastrointestinal carcinoid, tumors of the pancreas or adrenal glands (pheochromocytoma).
Clinical symptoms of G / A result from excess GH and an increase in the weight of the pituitary tumor. The acceleration of growth rate and excessive growth in children with correct body proportions are noticeable. Visual disturbances in the form of reduced visual acuity and narrowing of the visual field result from the pressure of the growing pituitary tumor on the optic junction. There may also be symptoms of deficiency of other hormones in the anterior pituitary gland due to pressure from a growing tumor – inhibition of sexual maturation, and much less often hypothyroidism or adrenal glands. Symptoms of diabetes insipidus may occur as a result of disturbances in the secretion of antidiuretic hormone. Sometimes pituitary adenoma – in addition to GH – also secretes other hormones: Prl, gonadotropins, TSH or alpha, beta-subunits.
In most cases, the concentration of GH is elevated under basal conditions, but sometimes it may only slightly exceed the upper limit of the reference value. Patients with G / A show clearly elevated IGF-I concentrations, significantly exceeding the reference value range for sex and age. This parameter is considered more constant than elevated GH levels. The finding of no suppression of GH secretion below 2 ng / ml between 60 and 120 minutes of the oral glucose loading test confirms the diagnosis of G / A. The GH secretion stimulation test after TRH is not so important in the diagnosis of G / A, as elevated GH values after TRH are found in 60-70% of G / A cases, but also in tall people without signs of gigantism in the pubertal period. MRI of the pituitary gland with contrast enables the assessment of the size of the tumor and its location. Do not forget about the necessary tests – ophthalmological, with the assessment of the field of view, and neurological
Source: A. Cajdler-Łuba, S. Mikosiński, A. Sobieszczańska-Jabłońska, I. Nadel, I. Salata, A. Lewiński: “FUNCTIONAL DIAGNOSTICS OF HORMONAL DISORDERS WITH ELEMENTS OF DIFFERENTIAL DIAGNOSTICS; Czelej Publishing House