The Secondary Adrenal Insufficiency

Lab results from a 30-year-old male show low urinary cortisol, low serum cortisol and no electrolyte abnormalities. Serum ACTH levels are also low. The man presented to his physician 3 days earlier with fatigue and depression. Which of the following is the most likely diagnosis?

Cushing’s Syndrome
Primary Adrenal Insufficiency
Secondary Adrenal Insufficiency
Sheehan’s Syndrome

Correct answer
Secondary Adrenal Insufficiency
correct answer: D

Low urinary and serum cortisol should immediately make you think of adrenal insufficiency. To discriminate between primary and secondary, it is important to evaluate blood ACTH levels. While ACTH levels are high in the Primary type (indicating a failure of the adrenal glands to produce cortisol when stimulated by ACTH), the Secondary type manifests with low ACTH levels (indicating failure of the pituitary gland to produce enough ACTH).