Primary Adrenal Insufficiency (Hypoadrenalism)

Primary hypoadrenalism is when the function of the adrenal gland is decreased and cannot meet the body's need to produce glucocorticoids, mineralocorticoids, and catecholamines. The disease can be detected in the adrenal gland, pituitary gland, or hypothalamus. Laboratory testing would help distinguish which organ is the source of the disease as shown in Table 4.

When the adrenal gland is hypofunctioning, it is called Addison's disease or primary hypoadrenalism. Addison's disease occurs in all age groups and sexes and can be life-threatening. Signs and symptoms include fatigue, low blood pressure, syncope, craving salty foods, hypoglycemia, nausea, emesis, diarrhea, muscle pain, irritability, and hyperpigmentation of skin and tissue. The laboratory plays a crucial role in the detection of Addison's disease. The main tests performed include serum hormones, insulin, and glucose levels.

Laboratory diagnostics of poor adrenal output generally include establishing initial reference values to serve as a baseline. Physicians often order serum tests for baseline values of ACTH, cortisol, glucose, and CRH. If these values come back abnormal, physicians can then follow up with reflex testing like synthetic ACTH, CRH stimulation tests, insulin-induced hypoglycemia assays, metyrapone ACTH stimulation, and CT scans.

Because the adrenal gland exhibits diurnal variation, the optimal time to test adrenal hormones is in the morning.