Growth hormone (GH) deficiency and GH replacement therapy in patients previously treated for Cushing's disease

Several complications associated with active Cushing's disease may persist even years after complete and successful therapeutic remission of hypercortisolism. Growth hormone deficiency (GHD) shares many clinical features seen in patients with Cushing's disease, and its presence after disease remission (GHD-CR) might negatively influence and potentially worsen the systemic complications caused by previous hypercortisolism. GHD-CR is more prevalent in women, and compared to other causes of GHD, patients are younger at the onset of the pituitary disease, at diagnosis of GHD-CR and at start of GH therapy; prevalence of pituitary macroadenomas and visual abnormalities are lower, while prevalence of diabetes, hypertension, low bone mass, fractures, and worst quality of life, are higher. Serum IGF-1 levels are not useful for the diagnosis of GHD-CR and the application of GH stimulating tests requires some special attention in addition to the general recommendations for detecting GHD from other etiologies. In patients with active hypercortisolism, GH secretion is completely suppressed, but it may spontaneously and progressively recover over the years following successful therapy, meaning that GH testing may be performed at an appropriate time after remission for the correct diagnosis. Moreover, if the patient presents concomitant adrenal insufficiency, GH testing should only be carried out under adequate cortisol replacement therapy. GH therapy in children with GHD-CR improves adult height in the majority of patients, while GH therapy in adults has been associated with improvements in body composition, lipid profile and quality of life, but also with worsening of glucose metabolism.