Adrenal Pathology
On this page
Direct answer
Adrenal pathology maps onto the cortex — glomerulosa for aldosterone (Conn syndrome), fasciculata for cortisol (Cushing syndrome, Addison disease), reticularis for androgens (congenital adrenal hyperplasia) — and the medulla for catecholamine tumours, phaeochromocytoma in adults and neuroblastoma in children. Conn syndrome pairs resistant hypertension with hypokalaemic alkalosis and a high aldosterone-to-renin ratio; Addison disease presents with hyperpigmentation, hyponatraemia and hyperkalaemia, from autoimmunity or tuberculosis, the latter a live Indian consideration; phaeochromocytoma delivers episodic headache, sweating and palpitations.
What you must remember
- Conn syndrome: aldosterone-producing adenoma or bilateral hyperplasia; resistant hypertension with hypokalaemia, alkalosis, weakness and polyuria; high aldosterone with suppressed renin diagnoses, and unilateral disease is cured by adrenalectomy, bilateral disease treated with spironolactone or eplerenone. Secondary hyperaldosteronism (renal artery stenosis, cirrhosis, heart failure) has high renin.
- Cushing syndrome: exogenous steroids the commonest cause; endogenous — pituitary ACTH disease commonest, ectopic ACTH from small cell lung cancer, adrenal adenoma or carcinoma. Screen with late-night salivary cortisol, 24-hour urinary free cortisol or overnight 1 mg dexamethasone; then ACTH level, with high-dose suppression and petrosal sinus sampling to separate pituitary from ectopic.
- Addison disease: primary failure with fatigue, postural hypotension, salt craving, hyperpigmentation of creases and mucosae, hyponatraemia, hyperkalaemia, hypoglycaemia and eosinophilia; autoimmune in the West, tuberculosis the classic Indian cause; short Synacthen test confirms; crisis treated with intravenous hydrocortisone and saline.
- Congenital adrenal hyperplasia: 21-hydroxylase deficiency commonest — cortisol and aldosterone fall, androgens rise, giving salt-wasting neonatal crisis with ambiguous genitalia in girls and precocious puberty in boys; 17-alpha-hydroxylase deficiency instead causes hypertension with hypokalaemia without virilisation.
- Phaeochromocytoma: episodic triad of headache, sweating and palpitations with paroxysmal hypertension; diagnosis by plasma or urinary metanephrines, localisation by CT or MIBG; MEN2, von Hippel-Lindau and NF1 associations; alpha-block (phenoxybenzamine) before any beta blocker; malignancy judged only by metastases.
- Neuroblastoma: adrenal medulla tumour under age five with a large abdominal mass, opsoclonus-myoclonus (dancing eyes) and Homer-Wright rosettes; N-myc amplification predicts poor outcome; urinary VMA and HVA aid diagnosis.
Common confusion
Primary versus secondary adrenal insufficiency separates on pigmentation and potassium: primary failure raises ACTH-driven pigmentation with hyperkalaemia, secondary pituitary failure spares both. Primary versus secondary hyperaldosteronism is a renin story. In phaeochromocytoma, beta blockade first causes unopposed alpha vasoconstriction and hypertensive crisis — always alpha-block first.
Exam-focused takeaway
FMGE loves the sequence: electrolyte or pigment cue to the syndrome, confirmatory test, then localisation. Expect single-liners on the aldosterone-to-renin ratio, high-dose dexamethasone interpretation, Synacthen testing, 21-hydroxylase features, metanephrine diagnosis and alpha-before-beta blockade. Tuberculosis-Addison and the dancing-eye child are recurring Indian vignettes.
Frequently asked questions
Why is renin low in Conn syndrome?
Autonomous aldosterone expands volume and raises pressure, suppressing juxtaglomerular renin; a high aldosterone-to-renin ratio therefore confirms primary disease.
How is Cushing syndrome localised?
Confirm cortisol excess, measure ACTH — low points to an adrenal source, high to pituitary or ectopic — then separate by high-dose dexamethasone suppression and petrosal sinus sampling before imaging.
What separates primary from secondary adrenal failure?
Primary destruction raises ACTH, causing hyperpigmentation and mineralocorticoid loss with hyperkalaemia; secondary deficiency spares pigmentation and potassium, giving isolated glucocorticoid failure.
Which enzyme causes salt-wasting congenital adrenal hyperplasia?
21-hydroxylase, blocking cortisol and aldosterone while shunting precursors to androgens — neonatal salt-losing crisis with ambiguous genitalia in girls. Replacement is lifelong.
How is phaeochromocytoma diagnosed?
Plasma free metanephrines or 24-hour urinary fractionated metanephrines as the most sensitive screen, then CT or MRI and MIBG; genetic testing for RET, VHL and NF1 in familial or bilateral disease.
What is opsoclonus-myoclonus syndrome?
Chaotic eye movements with myoclonus as a paraneoplastic sign of neuroblastoma, often at low tumour burden; tumour treatment plus immunotherapy helps many children.