Clinical Pearls & Morning Reports
What are some of the clinical and laboratory findings associated with primary adrenal insufficiency?
Hyponatremia can occur in all forms of adrenal insufficiency, although it tends to occur most prominently in primary adrenal insufficiency (Addison’s disease). Primary adrenal insufficiency is caused by impairment of the adrenal glands, whereas secondary adrenal insufficiency is the result of corticotropin deficiency caused by either pituitary or hypothalamic disease. A Case Record of the Massachusetts General Hospital explains.
Q: What is the most common cause of primary adrenal insufficiency in high-income countries?
A: Primary adrenal insufficiency is a rare entity, and in high-income countries, autoimmune adrenalitis is the most common cause.
Q: Do patients with adrenal insufficiency have a normal life expectancy?
A: Patients with adrenal insufficiency have a mortality rate that is 2 or 3 times the normal rate, and they have an increased incidence of certain cancers. Morbidity is considerable. Patients often have absences from school or work, frequent hospitalizations, and alterations in work life, social life, family life, and physical activity.
A: The signs and symptoms are nonspecific and include fatigue, dizziness, gastrointestinal illness, salt craving, and hyperpigmentation. Hyperpigmentation is almost always present in chronic primary adrenal insufficiency. There are also some case reports of chronic primary adrenal insufficiency in which hyperpigmentation is absent, most likely because there are adequate resting levels of plasma cortisol, which would prevent increased corticotropin secretion and subsequent melanocyte stimulation. Among patients with adrenal insufficiency, hyperkalemia occurs only in those with the primary form, owing to the aldosterone deficiency. Hyperkalemia occurs in only 50 to 60% of patients with primary adrenal insufficiency, perhaps because of aldosterone-independent regulatory mechanisms in the distal nephron that maintain eukalemia. A fraction of patients with adrenal insufficiency have a peripheral eosinophilia.
Figure 1. Laboratory Abnormalities in Primary Adrenal Insufficiency.
A: A 21-hydroxylase antibody test is approximately 60 to 75% sensitive, so a positive test would indicate an autoimmune cause, but a negative test does not rule it out. Other antibodies have been identified in patients with autoimmune primary adrenal insufficiency, such as antibodies against the steroid 17α-hydroxylase and side-chain cleavage enzymes. These tests are not widely available and are not specific.