Growth hormone (GH) plays a role in the regulation of protein, lipid, and carbohydrate metabolism during adult life. About three-quarters of adult growth hormone deficiency (GHD) cases are associated with pituitary tumours and subsequent surgery and radiotherapy. Clinical manifestations of GHD in adults include decreased lean body and muscle mass, increased fat mass, reduced bone mineral density, lipid profile changes, and psychiatric symptoms. Diagnosis of adult GHD is usually based on a medical history (childhood-onset GHD, hypothalamic–pituitary disease or surgery, cranial irradiation or traumatic brain injury) and biochemical tests (GH stimulation tests). In a European study, the prevalence of hypopituitarism was estimated to be 29 to 45 per 100,000, and the incidence 4.2 cases per 100,000. There are no data on prevalence or incidence of GHD in Canada.
Once diagnosed, patients with GHD may receive replacement therapy with somatropin, which is identical in amino acid sequence to endogenous GH and synthesized through recombinant DNA technology. The goals of replacement therapy are to correct the metabolic, functional, and psychological abnormalities associated with adult GHD. A number of somatropin products are available in Canada for replacement of endogenous growth hormone in adults with GHD, including Genotropin. The approved dose of Genotropin in this population is 0.15 mg to 0.3 mg per day, administered subcutaneously.
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