Adrenal Insufficiency in Critical Illness (CIRCI)

1. Definition

CIRCI (Critical Illness–Related Corticosteroid Insufficiency) refers to inadequate corticosteroid activity for the severity of illness, due to:

• Impaired adrenal cortisol production
• Altered cortisol metabolism
• Tissue glucocorticoid resistance

It is a functional, dynamic disorder of the HPA axis during severe stress — not classic Addison’s disease.

The term was formalized by the Society of Critical Care Medicine (SCCM) and European Society of Intensive Care Medicine (ESICM).

2. Normal HPA Axis vs Critical Illness

 Normal Physiology

Stress → Hypothalamus (CRH) → Pituitary (ACTH) → Adrenal cortex → Cortisol

Cortisol:

• Maintains vascular tone
• Enhances catecholamine responsiveness
• Maintains glucose homeostasis
• Modulates inflammation

 What Happens in Severe Critical Illness?

In sepsis, trauma, ARDS:

• Early phase → ↑ cortisol levels
• Later phase → dysregulated axis:
• ↓ ACTH pulsatility
• Impaired adrenal responsiveness
• ↑ cortisol metabolism
• Tissue resistance

➡ Net result = Relative cortisol deficiency

3. Pathophysiology of CIRCI

A. Central Mechanisms

• Cytokine-mediated suppression (IL-1, IL-6, TNF-α)
• Pituitary dysfunction
• Reduced ACTH secretion

B. Adrenal Dysfunction

• Adrenal ischemia
• Hemorrhage
• Mitochondrial dysfunction
• Drug suppression

C. Peripheral Cortisol Resistance

• Downregulation of glucocorticoid receptors
• Altered receptor affinity
• Increased 11β-HSD type 2 activity

4. Causes / Risk Factors in ICU

• Septic shock (most common)
• ARDS
• Major trauma
• Cardiac surgery
• Severe pancreatitis
• Prolonged mechanical ventilation
• ECMO
• Hepatic failure

5. Drug-Induced CIRCI

 A single induction dose of etomidate can suppress cortisol for 24–48 hrs.

6. Clinical Features

⚠ CIRCI does NOT present like classic Addisonian crisis.

Typical Features in ICU:

• Refractory hypotension
• Poor vasopressor response
• High vasopressor requirement
• Persistent septic shock
• Unexplained hypoglycemia
• Hyponatremia (less common than primary AI)
• Eosinophilia (sometimes)
• Prolonged mechanical ventilation

 Key clinical clue: Shock not responding to fluids + vasopressors.

7. Diagnosis of CIRCI

⚠ Important: Diagnosis is CLINICAL in septic shock.

Laboratory Tests

 Random Total Cortisol

• <10 µg/dL → Suggests adrenal insufficiency
• 34 µg/dL → AI unlikely
  

 ACTH Stimulation Test (250 µg cosyntropin)

• Delta cortisol <9 µg/dL → Suggests CIRCI

⚠ However:

• Albumin low → total cortisol misleading
• Critical illness alters cortisol-binding globulin
• Free cortisol assays not widely available

SCCM/ESICM 2017 Update

 Do NOT delay steroids for testing in septic shock.
 ACTH test is NOT required before starting therapy.
Testing does not predict response to steroids.

Diagnosis of CIRCI in septic shock is clinical, not laboratory-based.

9. When to Suspect CIRCI in ICU?

According to modern critical care consensus:

✔ Septic shock requiring:

• ≥0.25–0.5 µg/kg/min norepinephrine
• Persistent shock >4 hours
• Vasopressor dependence

✔ Shock unresponsive to fluids + vasopressors

9. Management

 Indication for Steroids (Septic Shock)

Current international guidelines (including Surviving Sepsis Campaign):

 Use IV hydrocortisone in:

• Septic shock
• Ongoing vasopressor requirement despite adequate fluid resuscitation

Duration:

• 5–7 days
• Or until shock resolution

Should Fludrocortisone Be Added?

Some trials (APROCCHSS) used:

• Hydrocortisone + Fludrocortisone 50 µg/day

But:

• Not universally required
• Hydrocortisone has mineralocorticoid activity

10. Major Clinical Trials

# CORTICUS Trial

• Faster shock reversal
• No mortality benefit

# ADRENAL Trial

• No mortality benefit
• Shorter shock duration
• Earlier ICU discharge

# APROCCHSS Trial

• Mortality reduction observed
• Combination therapy

 Overall conclusion:
Steroids reduce time to shock reversal; mortality benefit inconsistent.

11. Mechanism of Benefit in Septic Shock

Steroids:

• Restore vascular responsiveness to catecholamines
• Reduce nitric oxide overproduction
• Reduce inflammatory cytokines
• Improve myocardial function

12. Risks of Steroid Therapy

⚠ No significant increase in superinfection in major trials.

13. CIRCI in Non-Septic Conditions

 ARDS-Low-dose steroids improve ventilator-free days.

Severe CAP-Steroids reduce treatment failure in severe pneumonia.

Post-cardiac arrest-Not routinely recommended.

Trauma-Controversial.

14. Weaning Steroids

If:

• Short course (<7 days)
• No prior steroid exposure

👉 No taper required.

If prolonged course:Gradual taper recommended.