Clinical Features and Diagnosis of Adrenal Hypofunction (Addison's Disease)

Chronic Clinical Manifestations

• The American College of Endocrinology recommends recognizing Addison's disease by its characteristic constellation of chronic symptoms, including hyperpigmentation, profound fatigue, weight loss, orthostatic hypotension, and salt craving, along with laboratory findings of hyponatremia, hyperkalemia, low cortisol, and markedly elevated ACTH 1, 2
• Patients with Addison's disease often develop insidious symptoms over months to years, including profound fatigue and weakness, unintentional weight loss, and malaise 1
• Hyperpigmentation is a distinguishing feature of primary adrenal insufficiency, with uneven distribution especially in sun-exposed areas 1
• Orthostatic hypotension is a cardinal manifestation reflecting mineralocorticoid deficiency 2
• Nausea occurs in 20-62% of patients, and morning nausea and lack of appetite are particularly common 1
• Muscle pain or cramps, especially during acute crisis, are common complaints 1
• Salt craving is a highly specific symptom reflecting mineralocorticoid deficiency 3, 1

Laboratory Abnormalities in Chronic Disease

• Hyponatremia is present in 90% of newly diagnosed cases, caused by sodium loss in urine and impaired free water clearance 4, 1, 2
• Hyperkalemia occurs in approximately 50% of cases at diagnosis, caused by aldosterone deficiency, impaired glomerular filtration, and acidosis 4, 1, 2
• Low serum cortisol with markedly elevated plasma ACTH are characteristic 1, 2
• Elevated plasma renin activity (PRA) reflects mineralocorticoid deficiency 4
• Low DHEAS, androstenedione, and testosterone indicate androgen deficiency 1

Acute Adrenal Crisis Presentation

• Acute adrenal crisis is a life-threatening emergency that must be recognized immediately and treated without delay, characterized by severe malaise, profound fatigue, nausea, vomiting, severe abdominal pain, dehydration, hypotension, and impaired cognitive function 5, 1
• Hyponatremia and hyperkalemia are typical in acute adrenal crisis 5
• Increased creatinine due to prerenal renal failure is common in acute crisis 5, 1
• Hypoglycemia, particularly in children, can occur during acute crisis 5, 4

Critical Diagnostic Pitfalls

• The insidious nature of symptom development often leads to delayed diagnosis, and symptoms are frequently non-specific in early stages 1
• Diagnosis is often delayed even when biochemical proof is evident because the clinical presentation can be difficult to recognize 6
• Do not rely solely on the classical combination of hyponatremia and hyperkalemia for diagnosis, as serum sodium levels are often only marginally reduced and potassium is elevated in only approximately half of patients at diagnosis 4, 1

Associated Autoimmune Conditions

• Approximately 50% of patients with autoimmune primary adrenal insufficiency develop another autoimmune disorder during their lifetime, requiring continuous surveillance 3
• Autoimmune polyendocrine syndrome type-1 (APS-1) and type-2 (APS-2) are associated with Addison's disease, and patients should be screened for thyroid dysfunction, type 1 diabetes mellitus, and pernicious anemia 3, 4, 6

Autoimmune Polyendocrine Syndromes Associated with Addison’s Disease

Autoimmune Polyendocrine Syndrome Type 1 (APS‑1)

• APS‑1 is defined by the presence of any two of the following three components: primary adrenal insufficiency, hypoparathyroidism, and chronic mucocutaneous candidiasis. 7

Autoimmune Polyendocrine Syndrome Type 2 (APS‑2)

• APS‑2 most commonly includes primary adrenal insufficiency together with primary hypothyroidism; it may also be associated with Graves’ disease, type 1 diabetes mellitus, autoimmune gastritis with vitamin B12 deficiency, and pernicious anemia. 7

Laboratory Indicators of Autoimmune Adrenal Insufficiency in Patients with Controlled Hypothyroidism

Hepatic Marker

• Mildly elevated serum bilirubin may be observed in adrenal insufficiency even when thyroid function is euthyroid, indicating the need for further endocrine evaluation. 8

Renal Marker

• A reduced glomerular filtration rate (≈ 65 mL/min) with a modestly increased serum creatinine is not explained by well‑controlled hypothyroidism alone and can reflect prerenal azotemia secondary to aldosterone deficiency in primary adrenal insufficiency. 8

Inflammatory Markers

• Normal erythrocyte sedimentation rate (≈ 9 mm/hr) does not exclude autoimmune adrenal insufficiency. 8
• Normal C‑reactive protein (≈ < 0.2 mg/L) also fails to rule out chronic adrenal insufficiency. 8