Glucocorticoids
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Direct answer
Glucocorticoids bind intracellular steroid receptors and suppress inflammatory and immune gene transcription, producing profound anti-inflammatory and immunosuppressive effects. They are grouped by duration — short-acting hydrocortisone, intermediate-acting prednisolone and methylprednisolone, and long-acting dexamethasone and betamethasone — with dexamethasone having about 25 to 30 times the anti-inflammatory potency of hydrocortisone and negligible mineralocorticoid activity. Therapeutic power comes with a predictable adverse-effect profile (hyperglycaemia, osteoporosis, infection, myopathy, cataract) and suppression of the hypothalamo-pituitary-adrenal axis, so therapy beyond about three weeks must be tapered rather than stopped abruptly.
What you must remember
- Equivalent doses: hydrocortisone 20 mg equals prednisolone 5 mg, methylprednisolone 4 mg and dexamethasone 0.75 mg — exam-standard conversions for switching therapy.
- Duration and use: short-acting hydrocortisone for adrenal replacement and adrenal crisis (100 mg intravenous bolus); intermediate prednisolone for most inflammatory disease, often alternate-day to spare the axis; long-acting dexamethasone for cerebral oedema, meningitis and severe COVID-19 hypoxaemia (6 mg daily in the RECOVERY trial).
- Placental crossing: dexamethasone and betamethasone cross the placenta — two 12 mg intramuscular doses 24 hours apart for fetal lung maturity in threatened preterm birth; prednisolone is largely inactivated by placental enzymes and is preferred for maternal disease.
- Adverse effects: hyperglycaemia and unmasking of diabetes, osteoporosis, peptic ulceration (especially with NSAIDs), infection and tuberculosis reactivation, proximal myopathy, posterior subcapsular cataract, growth suppression in children, hypertension, skin fragility and neuropsychiatric changes.
- Osteoporosis prophylaxis: calcium and vitamin D for all; bisphosphonate when prednisolone 7.5 mg or more daily is expected for three months or longer.
- Adrenal suppression: therapy beyond three weeks suppresses the HPA axis — withdraw gradually, and double the dose during physiological stress such as fever or surgery to avert an Addisonian crisis.
- Mineralocorticoid note: fludrocortisone is the mineralocorticoid used for replacement in primary adrenal insufficiency and orthostatic hypotension; hydrocortisone has mild salt-retaining activity that dexamethasone lacks.
Common confusion
Dexamethasone versus prednisolone is the recurring puzzle: dexamethasone is long-acting, mineralocorticoid-free and crosses the placenta and blood-brain barrier, which suits cerebral oedema, raised intracranial pressure and fetal lung maturation; prednisolone is intermediate, safer in pregnancy for the mother, and the workhorse for nephrotic syndrome, rheumatological and pulmonary disease. The second classic error is abrupt cessation after prolonged therapy.
Exam-focused takeaway
NEET-PG stem patterns include the cushingoid patient on long-term steroids asked about complications, dose-equivalence arithmetic, steroid choice in pregnancy (prednisolone for mother, dexamethasone for fetus), prophylaxis against steroid osteoporosis, and the cortisol or dexamethasone suppression logic in Cushing syndrome work-ups. Vignettes also test stress-dose steroid cover for surgery and the caution against live vaccines during immunosuppressive doses. Anchoring potency, duration and mineralocorticoid activity for each molecule resolves nearly every question.
Frequently asked questions
What are the dose equivalents among common steroids?
Hydrocortisone 20 mg, prednisolone 5 mg, methylprednisolone 4 mg and dexamethasone 0.75 mg are equipotent anti-inflammatory doses.
Why is dexamethasone preferred in cerebral oedema?
It is long-acting, has no salt retention, and penetrates the central nervous system well; it reduces vasogenic oedema around tumours and in infections such as tuberculous meningitis.
Why must long-term steroids be tapered?
Beyond about three weeks the hypothalamo-pituitary-adrenal axis is suppressed, and abrupt withdrawal risks acute adrenal insufficiency with hypotension and shock.
Which steroids are used for fetal lung maturity?
Intramuscular dexamethasone or betamethasone, 12 mg twice 24 hours apart, because they cross the placenta; prednisolone is largely inactivated by placental enzymes.
How is steroid-induced osteoporosis prevented?
Calcium and vitamin D supplementation for all, with a bisphosphonate added when 7.5 mg or more prednisolone daily is anticipated for at least three months.