Endocrine and metabolic · Moderate
This case is fictional and exists for study. It describes no real patient.
34 years · female
A 34-year-old female presents to the emergency department with a 3-month history of progressive fatigue, weight loss, dizziness, and abdominal discomfort. Over the past 24 hours, her symptoms have severely worsened following an episode of gastroenteritis, developing intractable vomiting and lethargy. On physical examination, she appears acutely unwell and profoundly dehydrated. Hyperpigmentation is noted over her palmar creases, pressure points, and buccal mucosa. Abdominal examination reveals generalized mild tenderness without peritonitis.
Vital signs
- HR
- 118 bpm
- BP
- 82/54 mmHg
- RR
- 22/min
- Temp
- 37.8 °C
- SpO₂
- 97%
Examination findings
- Hyperpigmentation of palmar creases and buccal mucosa
- Generalized abdominal tenderness without guarding
- Delayed capillary refill time of 3 seconds
Investigations
| Sodium | 126 mmol/L | reference: 135-145 |
| Potassium | 5.8 mmol/L | reference: 3.5-5.0 |
| Serum Glucose | 3.4 mmol/L | reference: 4.0-7.0 |
| Urea | 11.2 mmol/L | reference: 2.5-7.8 |
Question 1 of 3
What is the most likely diagnosis?
The clinical constellation of chronic fatigue, weight loss, mucosal hyperpigmentation, hyponatraemia, hyperkalaemia, hypoglycaemia, and haemodynamic collapse triggered by infection is classic for acute Addisonian crisis (primary adrenal insufficiency). Hyperpigmentation occurs because low cortisol causes high ACTH production, stimulating melanocytes; mineralocorticoid deficiency causes hyperkalaemia and hyponatraemia. Secondary adrenal insufficiency (pituitary aetiology) lacks hyperpigmentation and significant mineralocorticoid deficiency because aldosterone secretion remains largely intact via the renin-angiotensin system. Phaeochromocytoma causes paroxysmal hypertension and diaphoresis. Diabetic ketoacidosis presents with severe hyperglycaemia and acidosis, not hyponatraemic hypoglycaemia with skin pigmentation.
Teaching point: Hyperpigmentation paired with hyperkalaemia and hyponatraemia differentiates primary adrenal insufficiency from secondary adrenal insufficiency.
Question 2 of 3
What is the most appropriate initial management step?
An Addisonian crisis is a medical emergency requiring rapid volume expansion with IV 0.9% sodium chloride and immediate administration of IV hydrocortisone (100 mg bolus). Treatment must never be delayed to perform diagnostic confirmation such as a short Synacthen test. Oral medications are unsuitable due to ongoing vomiting and severe cardiovascular instability. High-dose IV hydrocortisone provides sufficient mineralocorticoid activity during the acute phase, so fludrocortisone is unnecessary initially.
Teaching point: In a suspected Addisonian crisis, immediate intravenous fluid resuscitation and IV hydrocortisone must be administered without waiting for confirmatory diagnostic tests.
Question 3 of 3
Once the patient is haemodynamically stabilized, which investigation is most appropriate to confirm the underlying diagnosis of primary adrenal insufficiency?
The short Synacthen (ACTH stimulation) test is the definitive diagnostic test for adrenal insufficiency; a failure of serum cortisol to rise adequately after synthetic ACTH administration confirms impaired adrenal reserve. 24-hour urinary free cortisol and overnight dexamethasone suppression tests are used to evaluate hypercortisolism (Cushing's syndrome), not adrenal insufficiency. Adrenal CT imaging can help identify structural causes (e.g., adrenal haemorrhage or tuberculosis) after biochemical confirmation, but is not the primary diagnostic test.
Teaching point: The short Synacthen test is the gold standard diagnostic investigation for confirming adrenal insufficiency following stabilization.
Key learning points
- Primary adrenal insufficiency features loss of both glucocorticoids and mineralocorticoids, presenting with hyponatraemia, hyperkalaemia, hypoglycaemia, and cutaneous hyperpigmentation.
- Addisonian crisis is an acute life-threatening emergency managed with prompt IV normal saline fluids and 100 mg IV hydrocortisone.
- Emergency treatment of acute adrenal crisis must never be delayed for diagnostic procedures such as the short Synacthen test.
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