Page 76 - Slipped Capital Femoral Epiphysis Pathogenetic and Clinical aspects

Chapter 4
frequent abnormality in SCFE (see section ‘‘Diagnostic endocrine measurements in SCFE’’).
Glucocorticoids and SCFE
Glucocorticoids (GC) are steroid hormones that are produced in the adrenal cortex. This production is regulated by adrenocorticotropic hormone (ACTH) by the anterior pituitary gland and corticotrophin-releasing hormone (CRH) by the hypothalamus. Synthetic analogues of these hormones are widely used in the treatment of a variety of diseases. Mineralocorticoids are also produced by the adrenal gland but are not discussed in this review.
GC in physiological concentration facilitate normal growth, whilst in excess, GC suppress physis chondrocyte proliferation, induces prolonged resting period and reduces matrix synthesis with increased apoptosis. These effects are induced indirectly by alterations of the GH-IGH-1 axis and directly by local effects through GC receptors that are expressed in the physis [14, 18, 38-40]. Furthermore, GC inhibits the sulphation of cartilage matrix, mineralization of new bone, osteoblast activity and stimulates bone resorption [22, 38, 40].
Long-term high GC concentrations cause growth retardation and osteoporosis. GC alters pulsatility and diminishes the secretion of GH from the pituitary through an elevation of hypothalamic somatostatin release. In addition, GC causes end- organ-insensitivity to the GH-IGF-1 axis by reducing expression of the GH and IGF-1 receptor in the physis. Furthermore, GC has direct effects on the growth plate mediated by the GC receptor, for example, increased apoptosis in the physis [14, 38-40]. The effects depend on the GC concentration used and the duration of exposure. GC growth-depressing effects may be partially counterbalanced by GH treatment [18, 40].
In conclusion, GC, mainly in long-term high concentrations, has negative effects on growth by direct and indirect mechanisms. The relation between SCFE and GC has not been yet demonstrated.
Vitamin D
Vitamin D is a group of fat-soluble steroids responsible for the intestinal absorption of calcium and phosphate. Vitamin D can be ingested as cholecalciferol or ergocalciferol and it can also be synthesized (from cholesterol) by sun exposure. In the liver, vitamin D is converted to calcidiol. Part of the calcidiol is converted
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