What endocrine problems may occur during long term follow up?
Long-term pituitary hormone deficiencies, after the 3 month perioperative period, are generally only associated with recurrent tumors or radiation therapy. The risk of hypopituitarism after conventional radiation therapy is estimated to be < 30% to 60% at 10 years and may be lower for SRS. The development of hypopituitarism generally follows a predictable pattern of hormone loss (GH ≈ LH/FSH > TSH ≈ ACTH > PRL). Posterior pituitary gland deficiencies (i.e., ADH and oxytocin) do not generally occur after radiation therapy. Expectant management for patients after radiation should consist of biannual clinical assessment and biochemical testing for pituitary hormones, and initiation of hormone therapy for any identified deficiencies.
In general, physiologic hormone replacement for any resulting gonadotroph, thyrotroph, growth hormone and corticotroph deficiencies and appropriate monitoring are important to avoid iatrogenic endocrine complications. For example, with central hypothyroidism, the adequacy of thyroid hormone replacement is best assessed with a free T 4 level (not TSH) and should be adjusted to the mid-normative range. For complete corticotroph deficiency, typical glucocorticoid replacement doses include prednisone (≈ 5 mg/day) or hydrocortisone (≈ 15–20 mg/day in 2–3 divided doses). Chronically higher glucocorticoid doses may result in Cushing’s syndrome–related complications (e.g., diabetes, hypertension, osteoporosis, and metabolic syndrome). Sex steroid replacement should also be given in a physiologic- and age-appropriate manner. Lastly, GH replacement is sometimes considered in adults with persistent symptoms of hypopituitarism/GH deficiency (e.g., central weight gain, fatigue, hypertension, etc.) after optimal replacements of the other pituitary hormones.