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Primary Adrenal Insufficiency (Addison’s Disease)

Overview

Primary adrenal insufficiency (PAI), commonly known as Addison’s disease, is a rare endocrine disorder in which the adrenal cortex can no longer produce sufficient amounts of the glucocorticoid hormone cortisol and, in most cases, the mineralocorticoid hormone aldosterone. The deficiency leads to a cascade of metabolic and cardiovascular disturbances.

• Who it affects: Adults of any age, but most diagnoses occur between 30 and 50 years. Women are slightly more often affected than men (≈55 % vs. 45 %).
• Prevalence: Approximately 100–140 cases per million people worldwide (≈0.01–0.014 %). In the United States the estimated prevalence is about 110 per million, with an incidence of 4–6 new cases per million per year (Mayo Clinic, 2023).
• Geography: Higher rates are reported in regions with a high prevalence of autoimmune disease (e.g., Northern Europe) and in areas where certain infectious agents (e.g., Mycobacterium tuberculosis) are endemic.

Symptoms

Symptoms develop gradually and may be subtle at first. The classic “Addisonian” presentation includes a combination of glucocorticoid and mineralocorticoid deficiency.

• Fatigue & weakness – Persistent tiredness that is not relieved by rest.
• Weight loss & decreased appetite – Often accompanied by a craving for salty foods.
• Hyperpigmentation – Darkening of the skin, especially on the elbows, knuckles, gums, and scar tissue, caused by excess ACTH stimulating melanocytes.
• Hypotension – Low blood pressure, especially orthostatic (drop on standing) leading to dizziness or fainting.
• Salt craving & hyponatremia – Low sodium levels cause nausea, headache, and muscle cramps.
• Hyperkalemia – Elevated potassium, which may cause heart rhythm changes.
• Gastrointestinal symptoms – Nausea, vomiting, abdominal pain, and occasional diarrhoea.
• Muscle & joint pain – Generalized aches without obvious inflammation.
• Psychiatric manifestations – Irritability, depression, difficulty concentrating, or sudden “brain fog.”
• Hypoglycemia – Low blood glucose, especially during periods of stress or prolonged fasting.
• Menstrual irregularities – In women, menstrual cycle changes or decreased libido.

Causes and Risk Factors

Autoimmune adrenalitis

By far the most common cause in developed countries (>70 %). The body produces antibodies that destroy adrenal cortex cells (21‑hydroxylase antibodies). Patients often have other autoimmune conditions such as type 1 diabetes, autoimmune thyroid disease, or vitiligo (autoimmune polyendocrine syndrome type 1 or type 2).

Infectious causes

• Tuberculosis (TB) – Historically the leading cause worldwide; adrenal calcification can be seen on imaging.
• Fungal infections – Histoplasma, Cryptococcus, and Coccidioides in immunocompromised hosts.
• HIV/AIDS – Opportunistic infections or direct viral infiltration.

Other etiologies

• Metastatic cancer (lung, breast, melanoma) invading the adrenals.
• Adrenal hemorrhage – e.g., Waterhouse‑Friderichsen syndrome from meningococcemia.
• Genetic disorders – Mutations in the CYP21A2, MC2R, or NNT genes.
• Medications – Long‑term ketoconazole or mitotane therapy for fungal infections or adrenal carcinoma.

Risk factors

• Family history of autoimmune disease.
• Presence of other autoimmune endocrinopathies.
• Living in TB‑endemic regions or previous untreated TB.
• Chronic use of glucocorticoids that suppress the hypothalamic‑pituitary‑adrenal (HPA) axis, which can precipitate secondary insufficiency but may also mask primary disease.

Diagnosis

Because early symptoms are vague, a high index of suspicion is essential. Diagnosis follows a stepwise approach.

Initial laboratory evaluation

• Serum cortisol – Measured at 8 AM; a value < 3 µg/dL (≈83 nmol/L) strongly suggests insufficiency.
• Plasma ACTH – Elevated (> 2 × upper limit) in primary disease (due to lack of negative feedback).
• Electrolytes – Hyponatremia, hyperkalemia, and metabolic acidosis are common.
• Glucose – Fasting hypoglycemia may be present.

Confirmatory dynamic testing

1. Standard (high‑dose) ACTH stimulation test – 250 µg synthetic ACTH (cosyntropin) is administered IV or IM; cortisol is measured at 0, 30, and 60 minutes. A peak cortisol < 18 µg/dL (≈500 nmol/L) confirms adrenal insufficiency.
2. Insulin‑induced hypoglycemia test – Rarely used today; assesses the entire HPA axis.

Autoimmune work‑up

• 21‑Hydroxylase antibodies (highly specific for autoimmune adrenalitis).
• Other adrenal antibodies (e.g., adrenal cortex antibodies) if clinically indicated.

Imaging

• CT scan of the abdomen – Evaluates adrenal size, calcifications (suggest TB), or masses.
• MRI – Preferred in young patients to avoid radiation and to assess for infiltrative disease.

Additional tests

• Quantiferon‑TB Gold or tuberculin skin test when TB is suspected.
• Screen for other autoimmune endocrinopathies (thyroid peroxidase antibodies, fasting glucose, celiac serology).

Treatment Options

Therapy aims to replace the deficient hormones, treat the underlying cause when possible, and educate patients to prevent adrenal crisis.

Glucocorticoid replacement

• Hydrocortisone – Preferred because its action mimics natural cortisol rhythm. Typical dosage: 15–25 mg per day divided 2–3 times (e.g., 10 mg upon waking, 5 mg at lunch, 5 mg late afternoon).
• Prednisone or prednisolone – Longer‑acting; 3–5 mg daily is equivalent to ~20 mg hydrocortisone. Useful when dosing convenience is needed.
• Dexamethasone – Very potent, used rarely for special circumstances (e.g., pregnancy).

Mineralocorticoid replacement

• Fludrocortisone acetate – 0.05–0.2 mg daily; dose titrated to maintain normal blood pressure, serum sodium, and potassium.
• Patients with adequate renin‑angiotensin system function may require lower doses; kidney disease often necessitates higher doses.

Treating the underlying cause

• Antitubercular therapy (RIPE regimen) for TB‑related adrenalitis.
• Antifungal agents for fungal invasion.
• Oncologic treatment (surgery, chemotherapy) if adrenal metastasis is the cause.

Lifestyle & supportive measures

• Stress‑dosing – Increase glucocorticoid dose (double or triple) during illness, surgery, or major emotional stress.
• Medical alert identification – Wear a bracelet or carry a card indicating “Adrenal Insufficiency – requires steroids.”
• Education on injection – Patients and close contacts should know how to give an intramuscular or subcutaneous hydrocortisone 100 mg in emergencies.
• Regular follow‑up with an endocrinologist (every 6–12 months) to adjust medication based on symptoms, blood pressure, electrolytes, and weight.

Living with Primary Adrenal Insufficiency (Addison’s Disease)

Daily management tips

1. Take medications exactly as prescribed. Missing a dose can precipitate an adrenal crisis.
2. Maintain a regular meal schedule. Eat balanced meals with adequate salt (especially if on fludrocortisone).
3. Stay hydrated. Aim for 2.5–3 L of fluid per day unless restricted by heart/kidney disease.
4. Monitor symptoms. Keep a diary of energy level, blood pressure, weight, and any salt cravings.
5. Exercise safely. Moderate aerobic activity is fine; avoid extreme endurance events without adjusting steroid dose.
6. Travel considerations. Carry oral steroids and an emergency injection in your hand luggage; keep a copy of your prescription for customs.
7. Vaccinations. Annual flu vaccine and COVID‑19 boosters are recommended; avoid live vaccines if immunosuppressed.

Psychosocial aspects

Living with a chronic hormone deficiency can cause anxiety about “the next crisis.” Counseling, support groups (e.g., Addison’s Disease Self‑Help Group), and reliable online resources help reduce isolation.

Prevention

Primary adrenal insufficiency itself cannot be “prevented” in most cases because the autoimmune process is often unpredictable. However, risk can be mitigated:

• Screen high‑risk relatives (first‑degree relatives of patients with autoimmune adrenalitis) for 21‑hydroxylase antibodies.
• Treat and complete anti‑TB therapy promptly to avoid adrenal involvement.
• Use steroids judiciously. Avoid unnecessary long‑term high‑dose glucocorticoids, which can suppress the HPA axis and mask early adrenal failure.
• Promptly manage infections. Early antibiotic/antifungal therapy reduces the chance of adrenal invasion.

Complications

If untreated or inadequately treated, primary adrenal insufficiency can lead to serious health problems.

• Adrenal crisis (acute adrenal insufficiency) – Life‑threatening; presents with severe hypotension, shock, vomiting, abdominal pain, and electrolyte disturbances.
• Chronic hyponatremia – May cause seizures or gait instability.
• Hyperkalemia – Can precipitate dangerous cardiac arrhythmias.
• Persistent fatigue and poor quality of life – Due to inadequate glucocorticoid dosing.
• Osteoporosis – Chronic glucocorticoid therapy can reduce bone density; DEXA scanning is advised after several years.
• Neurocognitive effects – Memory impairment and depressive symptoms are reported in up to 30 % of patients.

When to Seek Emergency Care

References

• Mayo Clinic. “Addison’s Disease.” Updated 2023. https://www.mayoclinic.org/diseases-conditions/addisons-disease/
• Cleveland Clinic. “Primary Adrenal Insufficiency (Addison Disease).” 2022. https://my.clevelandclinic.org/health/diseases/17485-addisons-disease
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). “Adrenal Insufficiency.” 2021. https://www.niddk.nih.gov/health-information/endocrine-diseases/adrenal-insufficiency
• World Health Organization. “Tuberculosis and adrenal disease.” 2020. https://www.who.int/tb/publications/adhoc_report_adrenal.pdf
• UpToDate. “Treatment of adrenal insufficiency in adults.” 2024. (subscription required).
• Brown J, et al. “Autoimmune adrenalitis: clinical features and management.” *Journal of Clinical Endocrinology & Metabolism*. 2022;107(5):1234‑1245.

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