Understanding the HPA Axis and Long-Term Steroid Use in Aspergillosis

For patients living with ABPA, CPA, or other forms of aspergillosis who have used steroids long term

What is the HPA Axis?

The HPA axis stands for the Hypothalamic–Pituitary–Adrenal axis. It’s a vital communication system between three parts of your body:

• The Hypothalamus (in the brain)
• The Pituitary gland (also in the brain)
• The Adrenal glands (on top of your kidneys)

These three work together to manage your body’s response to stress, regulate inflammation, and control levels of a hormone called cortisol.

Cortisol helps you respond to illness, injury, or stress. It also affects energy levels, blood pressure, immune function, and even mood.

How Does the HPA Axis Work?

Here’s a simplified version:

1. The hypothalamus senses stress or inflammation and sends a hormone called CRH to the pituitary.
2. The pituitary gland then sends ACTH to the adrenal glands.
3. The adrenal glands release cortisol, which acts throughout your body to reduce inflammation and keep your systems balanced.

Once enough cortisol is in the blood, it signals the brain to stop releasing more. This keeps the system in balance.

Why Aspergillosis Patients Need to Understand This

Many people with aspergillosis—especially those with ABPA (Allergic Bronchopulmonary Aspergillosis)—are treated with oral corticosteroids such as prednisolone. These steroids reduce inflammation but can also interfere with the HPA axis.

Over time, the body may stop producing natural cortisol because it detects enough from medication. This condition is called adrenal insufficiency (AI) or HPA axis suppression.

Symptoms of Adrenal Insufficiency (AI)

If your adrenal glands are underactive, especially after long-term steroid use, you may experience:

• Extreme fatigue or feeling drained
• Muscle weakness
• Joint pain
• Feeling dizzy or faint, especially when standing
• Low blood pressure
• Nausea, vomiting, or abdominal pain
• Loss of appetite
• Worsening of general health during mild illnesses

In severe cases, a lack of cortisol can lead to an adrenal crisis, which is a medical emergency.

What to Do if You Suspect Adrenal Insufficiency

• Never stop steroids suddenly. Your dose should always be tapered under medical supervision.
• If you’ve been on steroids for several weeks or more, ask your doctor whether you should be tested for adrenal insufficiency using a short Synacthen test, which checks how well your adrenal glands respond to a synthetic version of ACTH (not cortisol itself). Synacthen is not your natural corticosteroid, but it helps doctors assess whether your adrenal glands are producing enough natural cortisol..
• You may be switched from prednisolone to hydrocortisone, which is a more natural replacement for cortisol and easier to adjust during illness.

When to Stress Dose (and Why It Matters)

Your stress dosing plan must always be agreed with your doctor. It should be tailored to your specific needs and medical history. If your body is under stress (e.g., illness, surgery, trauma), it needs more cortisol. If your adrenal glands aren’t working properly, this extra cortisol must come from medication.

Common stress dosing scenarios include:

• Fever over 38°C
• Vomiting or diarrhoea
• Dental surgery or minor operations
• Respiratory infections or flare-ups
• Emotional trauma or physical injury

Typical stress dosing guidance:

• Double your usual dose for 2–3 days during mild illness
• Seek emergency care immediately if you can’t keep down tablets or feel seriously unwell. In some cases, emergency medical staff may need to inject hydrocortisone (100 mg intramuscularly) to stabilise you. This should only be done by trained professionals unless you have been specifically trained and advised to self-administer by your specialist.

Always carry:

• A Steroid Emergency Card
• A medical alert bracelet
• An emergency hydrocortisone injection kit if advised

Why Doctors May Switch You to Hydrocortisone

Even though prednisolone can be used to replace cortisol, some patients still experience symptoms of adrenal insufficiency while on it. This can happen because:

• The dose might be too low for your needs
• Prednisolone doesn’t follow the body’s natural cortisol rhythm, which peaks in the early morning and drops throughout the day
• During illness or stress, the body needs more cortisol, and prednisolone doesn’t automatically increase
• Individuals metabolise steroids differently, so a standard dose may not be right for everyone

Common symptoms despite taking prednisolone may include:

• Ongoing fatigue, especially in the morning or late afternoon
• Poor stress tolerance
• Dizziness or weakness during illness
• Slow recovery after infections

For these reasons, your doctor may switch you to hydrocortisone, which is:

• Shorter-acting and better mimics natural cortisol rhythms
• Easier to adjust during illness or stress
• Often better tolerated long term with fewer side effects Hydrocortisone is shorter-acting and more closely mimics the natural rhythm of cortisol. It is usually taken in two or three doses throughout the day — for example, a larger dose in the morning, a smaller dose at lunchtime, and sometimes a final small dose in the early afternoon. This schedule helps replicate the natural daily rise and fall of cortisol and may improve energy levels, mood, and overall well-being.. It may be preferred if:
• You’re tapering from long-term prednisolone
• You’ve developed confirmed adrenal insufficiency
• You need a safer long-term maintenance dose
• You experience steroid-related side effects

Key Reminders for Aspergillosis Patients

Do This	Why It Matters
Follow your tapering plan	Prevents adrenal crisis
Ask about adrenal testing if fatigued	Catches suppressed adrenal function early
Know your sick-day rules	Allows for stress dosing during illness
Consider switching to hydrocortisone	Safer, more natural for long-term hormone replacement
Carry emergency ID and hydrocortisone	Life-saving in a crisis

Final Thoughts

Long-term steroid use helps many aspergillosis patients control inflammation and stay well. But it comes with responsibilities — particularly the need to monitor for adrenal suppression.

Understanding the HPA axis, recognising symptoms of AI, and knowing when and how to stress dose can empower you to live safely and confidently with aspergillosis.

Always talk to your specialist team if you’re unsure about fatigue, tapering, or illness management. You are not alone — and support is available.

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