Physician Assistant Exam: Adrenal Glands
The adrenal gland is important physiologically for practice and the Physician Assistant Exam (PANCE). It’s responsible for the production of cortisol, aldosterone, and the sex hormones as well. You don’t want to miss an abnormally functioning adrenal gland, either in clinical practice or on the PANCE.
The hypothalamus-pituitary-adrenal axis is a mini endocrine system that’s well-connected. When you evaluate test questions on problems that affect any of these three organs, first think about how a dysfunction in one organ affects the others in the system.
With adrenal insufficiency, first figure out whether you’re dealing with primary or secondary adrenal insufficiency:
Primary: Primary adrenal insufficiency (PAI), also known as Addison’s disease, refers to a problem with the adrenal gland itself. There are abnormalities related to both cortisol and aldosterone secretion.
Secondary: Secondary adrenal insufficiency refers to a problem with the pituitary gland (it’s unable to secrete ACTH), affecting the adrenal gland’s ability to secrete cortisol. Unlike with primary adrenal insufficiency, aldosterone production stays intact in secondary adrenal insufficiency. This is a key point to remember for questions on adrenal insufficiency.
Although there can be several etiologies of primary adrenal insufficiency, the biggest cause is an autoimmune adrenalitis that can destroy the adrenal gland. Other causes include malignancy and other infiltrative conditions and certain infectious processes.
Waterhouse-Friderichsen syndrome (WFS) is hemorrhage of the adrenal glands secondary to meningococcemia. This infection is very bad and is usually caused by Neisseria meningitidis. The infection is a systemic problem and can be fatal if not recognized early — we’re talking shock and the potential for developing disseminated intravascular coagulation (DIC).
Here are the key points about primary adrenal insufficiency:
Early symptoms are nonspecific and can include just fatigue, weakness, and weight loss. As the condition worsens, orthostatic symptoms can occur, with a drop in blood pressure upon standing.
Classic findings include hyperpigmentation along the skin creases and decreased hair in the axillary and pubic areas.
An abnormal blood work lab includes hyponatremia, hyperkalemia, and anemia. Eosinophilia may be present as well.
Note that hyponatremia and hyperkalemia are present in primary adrenal insufficiency, not secondary adrenal insufficiency. This happens because aldosterone, whose job is the retention of sodium and the excretion of potassium, is low to nonexistent in primary adrenal insufficiency but is present in secondary adrenal insufficiency.
A suggestive diagnostic test is a low morning cortisol of < 5 mg/dL. The confirmatory test is the cosyntropin (ACTH) stimulation test. In response to ACTH, the cortisol level should increase by 8 to 10 points in 60 minutes. If primary adrenal insufficiency is present, then a cosyntropin stimulation test will get little or no response.
The treatment is usually oral steroid replacement, usually in divided doses totaling 5 to 7.5 mg/day. If a person is deficient in aldosterone, then synthetic fludrocortisone acetate (Florinef) can be given.
An Addisonian crisis is a medical emergency and requires prompt recognition and treatment. In this situation, a significant body stressor stresses out an already-underfunctioning adrenal gland. The gland can’t make enough cortisol to deal with the body stressor.
The key is the administration of intravenous steroids, in addition to volume repletion, and pressor medications if needed to help maintain blood pressure. A search for and treatment of the underlying cause, such as infection, is vital. If you suspect an Addisonian crisis, don’t wait for a cortisol level to come back before treating the condition. The intravenous steroids can be life-saving in this situation.
Cushing’s syndrome represents an excess secretion of cortisol. First, establish that the person hasn’t been taking steroids, because steroids cause similar symptoms. Then the key is figuring out what’s causing the Cushing’s syndrome.
Symptoms of excess cortisol secretion from any cause include the classic moon face, buffalo hump, abdominal striae, and hypertension. People with Cushing’s may also have muscle weakness in the proximal muscles. You also see weight gain and centripetal obesity with Cushing’s syndrome. Metabolic syndrome or hyperglycemia, as well as edema, can also be present.
Cushing’s syndrome is diagnosed either by an elevated 24-hour urinary free cortisol test or via a low-dose dexamethasone suppression test. Normally, after administering 1 mg of dexamethasone at midnight, you see inhibition of cortisol secretion by the adrenal gland, as evidenced by a very low cortisol level in the morning. But in Cushing’s syndrome, the morning cortisol isn’t suppressed.
After one of these tests confirms that someone has Cushing’s syndrome, you need to ask, “Where in the body is the excess cortisol being secreted from?” Cushing’s disease represents excess ACTH secretion from the pituitary gland. But Cushing’s disease is just one cause of Cushing’s syndrome; other causes include a tumor in the adrenal gland or paraneoplastic ACTH secretion from a primary lung malignancy.
Here are key points about Cushing’s syndrome:
MRI is the test of choice to diagnose a pituitary adenoma.
Imaging the adrenals, usually with a CT scan, is important in looking for an adrenal tumor. If you find an adrenal or pituitary tumor, surgical removal is recommended.
Ectopic ACTH production secondary to a lung cancer can be associated with significant hypokalemia and a metabolic alkalosis.
You are evaluating a 25-year-old woman who has been transferred to the ICU secondary to profound hypotension. Her blood pressure is 75/40 mmHg with a pulse of 120 beats per minute. Her monitor shows she is in a normal sinus rhythm. Despite intravenous fluids and pressor medications, her blood pressure remains low. You suspect adrenal insufficiency. What is your next step?
(A) Check a stat random cortisol level.
(B) Do a 24-hour urinary free cortisol.
(C) Do an ACTH stimulation test.
(D) Do a low-dose dexamethasone suppression test.
(E) Give hydrocortisone 100 mg intravenously stat.
The answer is Choice (E). This patient is likely having an Addisonian crisis. Give intravenous steroids in this situation.