Mackenzie SD, Gifford RM, Boyle LD, et al. - In both outpatient and medical inpatient settings, researchers recognized and validated criteria for morning and afternoon serum cortisol, which might be utilized to assess which patients require dynamic testing. The study sample consisted of 2,768 individuals going to endocrinology clinics and patients admitted to general medical units in two hospitals in Edinburgh, UK. According to this retrospective analysis, a morning (8 a.m.-12 p.m.) serum cortisol of < 275 nmol/L identified subnormal stimulated cortisol with 96.2% sensitivity, while a cut off of < 250 nmol/L achieved 96.1% sensitivity for afternoon (12 p.m.-6 p.m.) samples. In the validation cohort, sensitivity was maintained when the criteria were applied to outpatients for both morning and afternoon samples. For inpatients, only morning samples were sufficiently sensitive to the test. A sole serum cortisol measurement may be able to significantly lessen the need for dynamic testing in evaluating adrenal insufficiency, whether taken in ambulatory clinics in the morning or afternoon, or in morning samples from medical inpatients.