A patient with persistent hypotension, vomiting, hypoglycemia, hyponatremia, hyperkalemia, and new or marked hyperpigmentation raises urgent concern for adrenal crisis. Should you give hydrocortisone now, or protect the diagnostic workup by waiting for a cosyntropin stimulation test? In an unstable patient, that is a false choice: draw paired baseline cortisol and ACTH if it takes no time, then treat. If sampling would slow resuscitation, give hydrocortisone first.
In this case, the combination of autoimmune thyroid disease, progressive fatigue and weight loss, low blood pressure, and electrolyte abnormalities makes primary adrenal insufficiency plausible. Hyperpigmentation and hyperkalemia support primary rather than central adrenal insufficiency, but neither is required, and neither confirms the diagnosis. The provided history does not establish prior adrenal disease, steroid exposure, or baseline function; clarify those details as resuscitation proceeds.
Make the blood draw parallel—not a gate
The useful early diagnostic move is a paired serum cortisol and plasma ACTH obtained before glucocorticoid administration, when feasible. A low cortisol with a substantially elevated ACTH supports primary adrenal insufficiency; renin and aldosterone can help assess mineralocorticoid deficiency later. A baseline sample preserves information, but it is not a reason to wait for the result before treating shock.
| Situation | Practical ED approach |
|---|---|
| Unstable or deteriorating, with adrenal crisis suspected | Draw cortisol and ACTH only if the samples can be obtained immediately during ongoing resuscitation. Give parenteral hydrocortisone without waiting for results or cosyntropin testing. |
| Hemodynamically stable and testing is immediately available | A clinician may obtain baseline samples and perform cosyntropin testing if doing so will not delay needed treatment. |
| Hydrocortisone has already been given | Record the agent and time. Do not interpret a subsequent serum cortisol as an untreated baseline; arrange confirmatory testing after stabilization. |
For an adult with suspected adrenal crisis, guideline-based initial treatment is hydrocortisone 100 mg IV or IM, followed by 200 mg over 24 hours by continuous infusion or divided dosing of 50 mg every 6 hours, alongside appropriate fluid resuscitation. Correct hypoglycemia and manage ECG-toxic hyperkalemia in parallel. Keep evaluating for other causes of shock as well: infection, including a possible urinary or gastrointestinal source, can precipitate crisis and may independently require urgent treatment.
Why hydrocortisone complicates testing—but should not be withheld
Hydrocortisone is cortisol. After it is administered, routine serum cortisol measurement cannot distinguish the medication from the patient’s own cortisol, so a post-dose result cannot serve as the original baseline. Glucocorticoid treatment can also alter ACTH through feedback. Documenting a pre-treatment sample, if immediately obtainable, is therefore useful—but preserving a clean test is secondary to treating a life-threatening presentation.
Cosyntropin testing is confirmatory, not the first resuscitation step for someone whose circulation is failing. Once the patient is stable, the team can plan testing with endocrinology and the laboratory. Any temporary adjustment to glucocorticoids should be planned safely; do not stop essential replacement just to obtain a test.
Is dexamethasone a universal workaround?
Dexamethasone is often taught as an alternative when clinicians want to give a steroid while keeping cortisol assays interpretable. Most modern cortisol assays do not materially cross-react with dexamethasone, but the laboratory’s method should be confirmed. That analytical advantage does not preserve an untreated baseline: dexamethasone suppresses ACTH and endogenous cortisol. It also has little to no mineralocorticoid activity—an important limitation when primary adrenal failure is suspected.
Dexamethasone may be a tailored option when there is a specific reason to retain the ability to measure cortisol after treatment and the laboratory or specialist team has confirmed that the assay is suitable. It is not a reason to delay treatment, and it should not displace standard hydrocortisone reflexively in an unstable patient. In this case, the suspected primary pattern and persistent hypotension favor acting on the emergency rather than optimizing the test.
Common traps
- Waiting for cosyntropin results before treating shock. The result is not needed to justify emergency treatment when suspicion is high.
- Assuming a post-hydrocortisone cortisol is the patient’s endogenous level. Record when the dose was given and interpret later testing in that context.
- Treating hyperpigmentation or hyperkalemia as mandatory criteria. They are useful clues, not required findings; their absence does not rule out adrenal insufficiency.
- Choosing dexamethasone solely from a memorized assay rule. Verify assay compatibility and remember the mineralocorticoid gap.
- Stopping the search after recognizing adrenal crisis. Continue looking for a trigger such as infection and treat coexisting causes of shock.
Practical takeaways
- In suspected adrenal crisis, obtain paired baseline cortisol and ACTH before steroids only when sampling causes no meaningful delay.
- Give parenteral hydrocortisone promptly to an unstable patient; do not wait for cortisol results or cosyntropin testing.
- Treat the post-dose cortisol as affected by exogenous hydrocortisone, and document the agent and administration time.
- Reserve dexamethasone as a laboratory- and context-dependent workaround, not a universal substitute for hydrocortisone.
- Complete confirmatory testing after stabilization with a safe, specialist-informed plan.
