Diagnosis of adrenal insufficiency

Cortisol is a glucocorticoid hormone secreted by the adrenal in a circadian manner in response to adrenocorticotropic hormone (ACTH) released from the pituitary, which is turn is stimulated by corticotropin releasing hormone from the pituitary. Cortisol has a critical role in homeostasis. Cortisol deficiency may present with nonspecific symptoms of lethargy, headache, nausea, abdominal pain, symptoms of hypoglycaemia and failure to thrive or weight loss or acutely with adrenal crisis (hypovolaemia, hypoglycaemia and collapse). Adrenal reserve can be assessed by measurements of cortisol in the early morning from late infancy, over 24 hours, or following the administration of a stimulant acting at the level of the pituitary or adrenal. All of the tests of adrenal reserve have limitations and results should always be interpreted in light of clinical features.