Early morning serum cortisol measured between 8 and 10 a.m. is the most commonly utilized measure of immediate remission following surgery. Cortisol secretion normally follows a diurnal pattern with highest levels between 7–9 a.m. that decline to lowest levels around 10–11 p.m. [9]. In patients with CD, the circadian rhythm is aberrant and cortisol levels remain consistently elevated [9, 10]. The goals of pituitary surgery are to extract the ACTH-secreting adenoma and subsequently reduce cortisol levels, leading to improvements in the signs and symptoms of CD.