Adrenal insufficiency and adrenal crisis — formative SAQs

SAQ 1 — The pigmented, losing-weight adolescent (20 marks, ~15 minutes)

A 14-year-old girl presents with four months of fatigue, nausea, abdominal pain and a 6 kg weight loss. Her mother says she has "gone brown". On examination she is tanned in the palmar creases, gum margins and old scars, with a postural drop in blood pressure. Sodium 126 mmol per litre, potassium 5.9 mmol per litre, glucose 2.6 mmol per litre. She has type 1 diabetes and autoimmune thyroiditis. [7]

Questions

1. Give the most likely diagnosis, the single set of first-line bloods that confirms it, and the expected ACTH and renin results. (5 marks) [1]
2. Outline the first-hour resuscitation if she collapses in the department, and state why treatment is not delayed for a confirmatory result. (5 marks) [4]
3. Explain the link to her type 1 diabetes and thyroiditis, and the further screening this implies. (4 marks) [7]
4. Describe the lifelong replacement regimen and the stress-dose and emergency plan you give the family. (6 marks) [1]

Model answer (must-hit)

1. This is primary adrenal insufficiency (autoimmune Addison disease) until proven otherwise. The hyperpigmentation, weight loss, postural hypotension, and the hyponatraemia with hyperkalaemia and hypoglycaemia are the full primary picture. Send a morning cortisol, ACTH, renin and aldosterone: cortisol is low, ACTH and renin are high, and aldosterone is low. Confirm with a 250-microgram cosyntropin stimulation test and 21-hydroxylase antibodies. [1]
2. Resuscitate on three tracks: 10 to 20 mL per kg of 0.9% saline repeated to perfusion; parenteral hydrocortisone 50 to 100 mg intravenously stat then 50 to 100 mg per square metre per 24 hours; and intravenous dextrose for the hypoglycaemia, with cultures and empiric antibiotics because sepsis coexists. The cortisol and ACTH confirm but do not resuscitate, so hydrocortisone is given empirically before the results return. [4]
3. Autoimmune Addison disease clusters with type 1 diabetes and autoimmune thyroiditis in autoimmune polyglandular syndrome type 2, so her presentation is the third endocrinopathy. Screen for the associated autoimmune diseases — thyroid function, coeliac screen, vitamin B12 and parietal-cell antibodies, gonadal status — and counsel the family, because a child with type 1 diabetes who develops fatigue and pigmentation has Addison until tested. [7]
4. Start oral hydrocortisone 8 to 12 mg per square metre per day in three divided doses with a larger morning dose, and add fludrocortisone 0.05 to 0.2 mg per day because she has primary disease. Build a stress-dose plan: double or triple the oral hydrocortisone for any febrile illness, give parenteral hydrocortisone if she vomits, and issue a parent-held emergency intramuscular hydrocortisone kit (adolescent 100 mg) with a MedicAlert and a school care plan. [1]

SAQ 2 — The steroid-withdrawn child (20 marks, ~15 minutes)

A 9-year-old boy treated for severe asthma with high-dose inhaled and oral corticosteroid for two years had his oral steroid tapered and stopped six weeks ago. He now presents with a febrile chest infection, vomiting and drowsiness. He is pale, cool peripherally, glucose 2.1 mmol per litre, sodium 130 mmol per litre, potassium 4.2 mmol per litre, blood pressure low. [6]

Questions

1. Give the most likely diagnosis and the single clue from the electrolytes that distinguishes it from primary adrenal failure. (4 marks) [6]
2. Outline the immediate management and the dose of parenteral hydrocortisone. (5 marks) [4]
3. Explain why the potassium is normal and why hyperpigmentation is absent. (5 marks) [6]
4. Describe the medium-term plan for his adrenal axis and the safety-net you build. (6 marks) [3]

Model answer (must-hit)

1. This is glucocorticoid-induced secondary adrenal insufficiency presenting as crisis, triggered by the febrile illness and the vomiting on a suppressed axis. The distinguishing clue is the normal potassium — aldosterone is intact in secondary disease, so the salt-wasting and hyperkalaemia of primary failure are absent, and the mild hyponatraemia comes from inappropriate antidiuretic hormone rather than salt loss. [6]
2. Give 10 to 20 mL per kg of 0.9% saline to perfusion, intravenous dextrose for the hypoglycaemia, and parenteral hydrocortisone 50 to 100 mg intravenously stat then 50 to 100 mg per square metre per 24 hours. Cover the chest infection with antibiotics, and escalate to paediatric intensive care if shock persists. [4]
3. Aldosterone secretion is governed by the renin-angiotensin system rather than by ACTH, so it survives the loss of pituitary ACTH drive and the potassium stays normal. Hyperpigmentation is driven by high ACTH and its melanocyte-stimulating POMC fragments; in secondary disease ACTH is low, so the child is pale rather than pigmented. [6]
4. Taper the hydrocortisone to a physiological replacement dose once the acute illness settles, and plan a slow wean over months while the axis recovers, because suppression can persist for many months after stopping steroid. Build a stress-dose plan, issue a parent-held emergency intramuscular hydrocortisone kit, and arrange follow-up with paediatric endocrinology and a low threshold to give stress doses at the next infection. [3]