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KembaraXtra- Medicine – Adrenal Insufficiency
Adrenal insufficiency refers to inadequate production of adrenal corticosteroids. It most classically results from partial or complete destruction of the adrenal cortex causing primary adrenal failure (Addison disease), in which cortisol deficiency is typically accompanied by impaired mineralocorticoid (aldosterone) production. In contrast, secondary cortisol deficiency results from pituitary (or hypothalamic) dysfunction leading to reduced ACTH stimulation of the adrenal glands, causing low cortisol but usually preserved aldosterone secretion, since aldosterone is mainly regulated by the renin–angiotensin system. Adrenal insufficiency can present gradually with nonspecific symptoms, and a high index of suspicion is required because up to about half of patients may first present with an acute adrenal crisis.
Adrenal insufficiency is relatively uncommon, with a prevalence of 10–15 per 100,000 persons, and occurs more often in females than males with an approximately 2:1 ratio. Clinical presentation may be insidious and includes generalized weakness, chronic fatigue, malaise, anorexia, weight loss, nausea, vomiting, abdominal discomfort, and postural dizziness. Hyperpigmentation of the skin and mucous membranes is a hallmark of primary adrenal insufficiency due to elevated ACTH and related melanocyte-stimulating activity; it is most prominent in palmar creases, buccal mucosa, pressure points (elbows, knees, knuckles), perianal mucosa, scars, and around the areolae. Hypotension and orthostasis are common. Women may have amenorrhea and loss of axillary hair due to adrenal androgen deficiency. Laboratory abnormalities often include hyponatremia, hyperkalemia (mainly in primary disease), hypoglycemia, and prerenal azotemia (elevated BUN/creatinine ratio). Additional findings can include mild normocytic anemia, neutropenia, lymphocytosis, eosinophilia, metabolic acidosis, and occasional hypercalcemia; severe dehydration can sometimes mask hyponatremia and anemia.
The most common cause of primary adrenal insufficiency is autoimmune adrenalitis, accounting for about 80% of cases. Other important causes include tuberculosis (historically significant, still relevant in some settings), metastatic or infiltrative malignancy (including lymphoma), adrenal hemorrhage (associated with anticoagulation, trauma, coagulopathies, pregnancy, or sepsis), adrenal infarction (e.g., antiphospholipid syndrome, thrombosis, arteritis), infections in immunocompromised states such as AIDS (with CMV adrenalitis), and genetic or syndromic causes including autoimmune polyglandular syndromes types 1 and 2, X-linked adrenoleukodystrophy, and congenital adrenal hyperplasia. Additional infiltrative etiologies include sarcoidosis, amyloidosis, hemochromatosis, vasculitides such as granulomatosis with polyangiitis, postoperative adrenal loss, and fungal infections such as histoplasmosis and candidiasis. Secondary adrenal insufficiency is usually due to pituitary disease, pituitary surgery or radiation, infiltrative pituitary disorders, or suppression of the hypothalamic–pituitary–adrenal axis following chronic exogenous glucocorticoid therapy.
Because symptoms overlap with many disorders, the differential diagnosis includes sepsis, hypovolemic shock, acute abdomen, depression, anorexia nervosa, chronic infection, gastrointestinal malignancy, myopathies, salt-losing nephritis, hemochromatosis, and in older adults “apathetic hyperthyroidism.” Diagnostic evaluation typically begins with assessment of cortisol production using an early morning (around 8 A.M.) serum cortisol. A cortisol level <3 mcg />L is strongly consistent with cortisol deficiency, while levels >18 mcg/dL generally exclude adrenal insufficiency. If the morning cortisol is 3-15 mcg/dL, confirmation is performed with a rapid ACTH (cosyntropin/Synacthen) stimulation test using 250 mcg ACTH IV, measuring cortisol at baseline, 30 minutes, and 60 minutes. A peak cortisol response >18 mcg/dL (≈500 nmol/L) suggests normal adrenal reserve, whereas failure to reach this threshold supports adrenal insufficiency. After confirming inadequate cortisol response, measuring plasma ACTH helps distinguish primary from secondary disease: ACTH >200 pg/mL supports primary adrenal insufficiency, while normal or low ACTH suggests secondary adrenal insufficiency. In critical illness–related corticosteroid insufficiency, a low-dose 1 mcg ACTH stimulation approach may be used, and an inadequate response may be defined by a cortisol level <25 mcg />L or an increment <9 mcg />L above baseline, depending on the clinical context.
Further evaluation aims to identify the cause. 21-hydroxylase antibodies are present in approximately 90% of autoimmune adrenalitis; if negative, adrenal imaging (typically CT) is recommended to assess for infection, hemorrhage, malignancy, or infiltrative disease. Tuberculosis evaluation may include PPD or interferon-gamma release testing. Imaging is not required to establish the diagnosis but can support etiology: small adrenal glands may indicate long-standing autoimmune atrophy or chronic tuberculosis, whereas enlarged glands can suggest early TB or other potentially treatable infiltrative processes. Chest radiography may show a small cardiac silhouette, and abdominal radiography can occasionally reveal adrenal calcifications in TB or fungal disease.
Management includes both chronic hormone replacement and urgent treatment of adrenal crisis. Patients should be educated on long-term monitoring of electrolytes, blood pressure, and weight, and generally advised to maintain a liberal sodium intake, especially in primary disease. They should carry a MedicAlert bracelet and an emergency kit containing injectable hydrocortisone, and both patients and partners should be trained to administer intramuscular steroids if vomiting or impaired consciousness prevents oral intake. Bone density monitoring may be considered because long-term glucocorticoid exposure increases osteoporosis risk.
Adrenal crisis is a life-threatening emergency characterized by circulatory collapse, dehydration, nausea/vomiting, hypoglycemia, hyperkalemia, and often severe hypotension. Treatment must begin immediately and should not be delayed for confirmatory testing. Initial steps include establishing large-bore IV access, drawing blood for electrolytes, glucose, cortisol, and ACTH, and rapidly infusing 2–3 liters of isotonic saline (0.9% NaCl) or dextrose-containing saline if hypoglycemia is present, with careful monitoring for fluid overload. Hydrocortisone 100 mg IV should be administered immediately and continued 100 mg every 6 hours, alongside supportive care and aggressive identification and treatment of precipitating causes such as infection, hemorrhage, or trauma. After stabilization, IV fluids are continued more slowly over 24–48 hours, the diagnosis is confirmed if previously unknown, glucocorticoids are tapered to maintenance dosing over 1–3 days as clinically appropriate, and mineralocorticoid replacement with fludrocortisone is started when stress-dose hydrocortisone is reduced and saline infusion is stopped.
Chronic treatment of primary adrenal insufficiency requires both glucocorticoid and mineralocorticoid replacement. A common regimen is hydrocortisone 15–20 mg on awakening with 5–10 mg in the early afternoon, or an alternative prednisone schedule such as 5 mg in the morning and 2.5 mg at bedtime, tailored to symptoms and avoidance of overtreatment. Fludrocortisone is generally required in primary disease, often starting around 0.1 mg daily (adjusted within a wider range based on orthostatic symptoms, blood pressure, edema, serum potassium, and plasma renin activity). Patients must be taught “sick day rules,” typically increasing glucocorticoid dosing two- to threefold for minor febrile illnesses for a few days without changing fludrocortisone dose, and using parenteral steroids if vomiting, diarrhea, severe illness, trauma, or surgery occurs. Stress-dose steroid coverage varies by severity: moderate illness may require hydrocortisone 50 mg twice daily orally or IV, while severe illness or shock can require hydrocortisone 100 mg IV every 8 hours with rapid tapering as recovery occurs. Minor procedures under local anesthesia often need no additional supplementation, whereas more stressful procedures may require a single 100 mg IV hydrocortisone dose just before the procedure, and major surgery typically requires 100 mg IV before induction followed by continued dosing for at least 24 hours with tapering.
In secondary adrenal insufficiency, mineralocorticoid replacement is usually unnecessary, and clinical clues include absence of hyperpigmentation and evidence of other pituitary hormone deficiencies such as hypothyroidism or hypogonadism. A critical safety point is that patients with both hypothyroidism and adrenal insufficiency should receive glucocorticoid replacement before thyroid hormone replacement, because thyroid hormone can increase cortisol clearance and precipitate adrenal crisis. Withdrawal from chronic exogenous steroid therapy should be gradual in patients treated for more than several weeks, with taper schedules individualized to dose and duration, and confirmation of hypothalamic–pituitary–adrenal axis recovery using appropriate stimulation testing when clinically indicated.
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