Okay, let's tackle this question about adrenal suppression from steroid therapy. First, I need to recall the core concept here. Adrenal suppression is a common side effect of prolonged corticosteroid use. The main idea is that exogenous steroids inhibit the hypothalamic-pituitary-adrenal (HPA) axis. The body stops producing its own cortisol because the external steroids are doing the job.

Now, the correct answer should relate to the mechanism of HPA axis suppression. Let's think about the options. The question is about what's true regarding this. The key points here are the dose and duration of steroid use. High-dose or long-term use is more likely to cause suppression. Also, the suppression can be reversible once the steroids are stopped, but it might take weeks to months for the HPA axis to recover.

For the wrong options: One might incorrectly think that low-dose therapy doesn't cause suppression, but even low doses can do it if given for a long time. Another wrong option could be about the timing of recovery—some might say it's irreversible, but in reality, it's usually reversible. Also, maybe an option about the mechanism involving ACTH instead of cortisol feedback; the correct mechanism is negative feedback on ACTH secretion from the pituitary.

The clinical pearl here is that patients on long-term steroids should be weaned gradually to avoid adrenal crisis. Also, during stress, they might need higher doses. The high-yield fact is that the HPA axis suppression is due to negative feedback on ACTH, leading to decreased cortisol production by the adrenal glands.

Putting it all together, the correct answer would be the one stating that adrenal suppression is due to negative feedback on the HPA axis, especially with prolonged or high-dose corticosteroid use. The incorrect options would be those that either deny the effect of low-dose therapy, claim irreversibility, or misstate the mechanism.

**Core Concept**
Adrenal suppression from steroid therapy occurs due to **negative feedback inhibition of the hypothalamic-pituitary-adrenal (HPA) axis**. Exogenous corticosteroids suppress **ACTH secretion** from the pituitary, leading to **atrophy of adrenal cortex** and reduced endogenous cortisol production.

**Why the Correct Answer is Right**
Prolonged or high-dose corticosteroid use causes **suppression of the HPA axis** by inhibiting **CRH (corticotropin-releasing hormone)** from the hypothalamus and **ACTH (adrenocorticotropic hormone)** from the pituitary. This leads to **decreased cortisol synthesis** in the adrenal cortex. Recovery of HPA function may take weeks to months after steroid discontinuation, especially after long-term therapy.

**Why Each Wrong Option is Incorrect**
**Option A:** Claims adrenal suppression is irreversible. Incorrect: Adrenal suppression is typically **reversible** once steroids are tapered appropriately.
**Option B:** Suggests low-dose steroids do not cause suppression. Incorrect: Even **low-dose corticosteroids** (e.g., <5 mg prednisone daily) can suppress the HPA axis over weeks to months. **Option C:** Attributes suppression to increased ACTH. Incorrect: Steroids cause **decreased ACTH** via negative feedback, not increased. **Clinical Pearl / High-Y

✓ Correct Answer: C. It should be expected in anyone receiving > 5mg, Prednisolone daily