Secondary adrenal insufficiency is usually caused by a pituitary mass. This patient has clinical signs of multiple hormone deficiencies and the classic clinical finding of a bitemporal hemianopsia. Deficiency in growth hormone due to pan-hypopituitarism may result in hypoglycemia.
Remember that adrenal insufficiency can be divided into primary, secondary, and tertiary causes. Primary adrenal insufficiency is also known as Addison's disease and is most often idiopathic or autoiummune but may also be due to infectious disease (i.e. tuberculosis), iatrogenic causes, or metastatic cancer. Secondary adrenal insufficiency is most often due to long-term exogenous steroid therapy, but rarely can be due to hypopituitarism as in this case. Finally, in tertiary adrenal insufficiency, hypothalamic disease is the culprit. In pan-hypopituitarism, all of the hormones from the anterior pituitary may be absent. LH, FSH, and GH are usually lost before TSH and ACTH. Although a pituitary tumor is the most common cause, other causes include radiation therapy, Sheehan's syndrome, sarcoidosis, cavernous sinus thrombosis, and trauma. Recall that pituitary tumors are 10% of intracranial neolpasms and almost all are benign. Compression of the hypothalamic-pituitary stalk is the most common cause of this patient's pan-hypopituitarism.
Lake et al. provide an overview of pituitary adenomas. Prolactinomas and nonfunctioning adenomas are the most common types of pituitary adenomas. Patients may present with infertility, decreased libido, galactorrhea, headache, and visual changes. Although tumors may be nonsecreting, the oversecreting tumors present with classical clinical syndromes such as hyperprolactinemia, acromegaly, and Cushing disease.
Ding et al. discuss treatment paradigms for pituitary adenomas. Treatment options include medical therapy, microscopic or endoscopic surgical resection, radiosurgery, and radiation therapy. The selection of the proper treatment depends on the biochemical profile of the tumor and the clinical status of the patient.
Image A depicts the classic visual field defect of bitemporal hemianopsia indicating a chiasmal mass.
Answers 1-3: Hyperkalemia, hyperpigmentation, and salt wasting occur in primary adrenal insufficiency but not in secondary adrenal insufficiency.
Answer 4: Plasma cortisol level would be depressed, not elevated, in secondary adrenal insufficiency.
Lake MG, Krook LS, Cruz SV. Pituitary adenomas: an overview. Am Fam Physician. 2013 Sep 1;88(5):319-27.
PMID:24010395 (Link to Abstract)
Ding D, Starke RM, Sheehan JP. Treatment paradigms for pituitary adenomas: defining the roles of radiosurgery and radiation therapy. J Neurooncol. 2013 Oct 12. [Epub ahead of print]
PMID:24122025 (Link to Abstract)