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Stem
A 36-year-old woman presents to the emergency department with a 3-day history of vomiting, abdominal pain, diarrhoea and progressive drowsiness. For six months she has noticed increasing fatigue, a 9 kg weight loss, salt craving, and progressive darkening of her skin and the creases of her palms. Her past history is notable for an autoimmune thyroid disorder and vitiligo. On examination she is drowsy, pulse 118/min, blood pressure 84/52 (60 lying and 40 standing), and she has marked bronzelike hyperpigmentation of the buccal mucosa, palmar creases, gum and recent surgical scars. There are patches of depigmentation on the forearms. Investigations: sodium 118 mmol/L (135 to 145), potassium 6.4 mmol/L (3.5 to 5.0), glucose 2.6 mmol/L (3.5 to 6.0), urea 14 mmol/L, venous pH 7.28, morning cortisol 78 nmol/L (250 to 700 at 8 am), plasma ACTH 1450 ng/L (10 to 60).
Questions
a) What is the diagnosis and the level of HPA-axis involvement? Justify with two features from the stem. (2 marks) Acute adrenal crisis on a background of primary adrenal insufficiency (autoimmune Addison disease). Primary (not secondary) is established by (1) markedly elevated ACTH (1450 ng/L) with low cortisol (loss of negative feedback from adrenal destruction), and (2) hyperpigmentation of buccal mucosa and palmar creases — driven by ACTH/MSH from POMC cleavage. The autoimmune aetiology is supported by coexisting autoimmune thyroid disease and vitiligo and the 6-month history of fatigue, weight loss and salt craving.
b) Outline the immediate resuscitation. Give the drug, dose, route and timing. (3 marks) The resuscitation bundle — applied simultaneously, before any further results (cortisol and ACTH already drawn):
- ABCDE; high-flow oxygen; two large-bore IV cannulae; cardiac monitoring (hyperkalaemia risk).
- Hydrocortisone 100 mg intravenous STAT, then 100 mg over 24 hours (continuous infusion or 50 mg IV every 6 hours). At this dose hydrocortisone provides sufficient mineralocorticoid activity — fludrocortisone is NOT needed acutely.
- 0.9 percent sodium chloride 1 L intravenous over 30 to 60 minutes, then 2 to 3 L over 24 hours guided by clinical response; add 5 to 10 percent dextrose for the hypoglycaemia.
- Identify and treat the precipitant — gastroenteritis or another infection is likely: blood/urine/stool cultures and broad-spectrum antibiotics empirically (e.g. ceftriaxone 2 g IV once daily).
- Intensive care monitoring; vasopressors for refractory shock will work only after hydrocortisone is given (cortisol restores catecholamine sensitivity).
- Taper — once stable (24 to 72 hours) halve the hydrocortisone daily until the oral maintenance dose (15 to 25 mg/day) is reached; add fludrocortisone 100 mcg daily when the hydrocortisone dose is at maintenance.
c) Two weeks later she is stable and ready for discharge. Outline the chronic replacement regimen, the sick-day rules, and the surgical stress-dose schedule for any future operation. (3 marks) Chronic replacement: Hydrocortisone 20 mg/day in divided doses (10 mg on waking, 5 mg at noon, 5 mg at 5 pm) + fludrocortisone 100 mcg orally each morning (primary AI only). Monitor wellbeing, blood pressure (including postural), electrolytes and plasma renin; titrate to a renin in the upper normal range. Sick-day rules: double the oral hydrocortisone for the duration of any febrile illness (typically 3 days); triple the dose, or give hydrocortisone 100 mg IM/IV, for severe illness, vomiting or major trauma. Vomiting is the trigger for parenteral hydrocortisone — never omit the dose. Surgical stress dosing: minor procedure — hydrocortisone 50 mg IV/IM at induction; moderate — 75 to 100 mg at induction then 50 mg every 8 hours for 24 hours; major surgery — 100 mg at induction then 200 mg per 24 hours for 24 to 48 hours, then taper. She must carry a Steroid Emergency Card, a medical alert bracelet, and an emergency hydrocortisone 100 mg IM injection kit, and her family must be taught to give the injection.
d) Two years later she is diagnosed with type 1 diabetes. What syndrome does this represent and what other conditions should you screen for? Name two pitfalls in her care. (2 marks) Autoimmune polyglandular syndrome type 2 (APS-2, Schmidt syndrome) — Addison disease + autoimmune thyroid disease + type 1 diabetes. Screen for: pernicious anaemia (vitamin B12), coeliac disease (tissue transglutaminase IgA), premature ovarian failure (FSH/LH/oestradiol), hypoparathyroidism (calcium/PTH), vitiligo, alopecia, autoimmune gastritis. Pitfalls: (1) Recurrent unexplained hypoglycaemia in her type 1 diabetes may indicate undertreated Addison (cortisol deficiency reduces gluconeogenesis and the insulin requirement falls). (2) Rifampicin (if she is ever treated for TB) accelerates cortisol metabolism — double the hydrocortisone dose. (3) Always start hydrocortisone BEFORE thyroxine if she develops hypothyroidism — thyroxine accelerates cortisol clearance and precipitates crisis.