Corticosteroid Dose Converter
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The steroid conversion calculator converts doses between different glucocorticoid medications based on their relative anti-inflammatory potency compared to prednisolone or hydrocortisone as reference standards. Glucocorticoids are a class of steroid hormones that exert profound anti-inflammatory and immunosuppressive effects, and they differ substantially in potency, duration of action, and mineralocorticoid activity. The need for dose conversion arises frequently in clinical practice when switching between oral and parenteral formulations, transitioning from high-potency to lower-potency agents, or adjusting for bioavailability differences. The standard equivalence table (based on anti-inflammatory potency) is: Prednisolone 5 mg equals Hydrocortisone 20 mg equals Dexamethasone 0.75 mg equals Methylprednisolone 4 mg equals Betamethasone 0.75 mg equals Triamcinolone 4 mg equals Prednisone 5 mg. These equivalences apply to anti-inflammatory potency only — mineralocorticoid potency differs markedly between agents. Hydrocortisone has significant mineralocorticoid activity, prednisolone has weak activity, and dexamethasone has virtually none. Duration of action also varies: hydrocortisone is short-acting (8-12 hours), prednisolone and methylprednisolone are intermediate-acting (12-36 hours), and dexamethasone and betamethasone are long-acting (36-54 hours). In clinical practice, knowledge of steroid equivalences is essential when prescribing for adrenal insufficiency replacement, managing inflammatory and autoimmune conditions, prescribing peri-operative steroid cover, and avoiding iatrogenic Cushing syndrome from inappropriate long-term dosing.
Equivalent anti-inflammatory dose: Prednisolone 5mg = Hydrocortisone 20mg = Dexamethasone 0.75mg = Methylprednisolone 4mg = Betamethasone 0.75mg = Triamcinolone 4mg; Conversion factor = Target potency equivalent / Source potency equivalent
- 1Identify the current glucocorticoid and its dose.
- 2Find the equivalent dose in the reference standard (prednisolone 5 mg units): divide current dose by the steroid's prednisolone-equivalent dose factor.
- 3Calculate the number of prednisolone 5 mg equivalents: this gives the total anti-inflammatory equivalence.
- 4Multiply the number of equivalents by the target steroid's dose per prednisolone-5mg-equivalent to get the target dose.
- 5Account for mineralocorticoid activity: if switching to dexamethasone or betamethasone (no mineralocorticoid activity) in a patient with borderline mineralocorticoid deficiency, additional fludrocortisone may be needed.
- 6Account for duration of action differences: when converting to longer-acting agents (dexamethasone), administer once daily; for shorter-acting agents (hydrocortisone), divide into 2-4 daily doses.
- 7Always consider the clinical context: patients with adrenal insufficiency require physiological replacement doses (equivalent to cortisol production of 5-10 mg prednisolone/day), not anti-inflammatory doses.
Dexamethasone is ~6.67x more potent than prednisolone per mg
Prednisolone 40 mg provides 8 prednisolone-equivalent units (40/5 = 8). Each unit equals dexamethasone 0.75 mg, so the equivalent dexamethasone dose is 8 x 0.75 = 6 mg. Note that dexamethasone has no mineralocorticoid activity and a much longer half-life, so clinical effects and timing of side effects differ.
15 mg prednisolone equivalent — usually given as single morning dose
Hydrocortisone 60 mg is equivalent to prednisolone 15 mg in anti-inflammatory potency. The switch from thrice-daily hydrocortisone to once-daily prednisolone is common when changing from parenteral to oral therapy, though the longer HPA axis suppression from prednisolone must be considered.
Stress-dose exceeds maintenance equivalence — physiological stress requires supra-physiological supplementation
For major surgery, the recommended peri-operative steroid cover (100 mg hydrocortisone at induction + continued 50 mg 6-hourly) far exceeds the anti-inflammatory equivalent of the patient's usual prednisolone dose. This is because major surgery creates a cortisol demand of 200-400 mg hydrocortisone-equivalent per day in stressed individuals.
Methylprednisolone 80 mg/day is the equivalent anti-inflammatory dose
Dexamethasone 16 mg/day is equivalent to approximately 80 mg methylprednisolone or 107 mg prednisolone per day — a very high anti-inflammatory dose. This conversion is used when transitioning between agents for immune-mediated conditions while maintaining equivalent immunosuppressive potency.
Converting between oral and intravenous steroid regimens when patients cannot take oral medications during hospitalisation, representing an important application area for the Steroid Conversion in professional and analytical contexts where accurate steroid conversion calculations directly support informed decision-making, strategic planning, and performance optimization
Calculating peri-operative steroid supplementation for patients on long-term glucocorticoid therapy undergoing surgery, representing an important application area for the Steroid Conversion in professional and analytical contexts where accurate steroid conversion calculations directly support informed decision-making, strategic planning, and performance optimization
Switching from high-dose IV methylprednisolone to oral prednisolone during tapering of immunosuppressive therapy, representing an important application area for the Steroid Conversion in professional and analytical contexts where accurate steroid conversion calculations directly support informed decision-making, strategic planning, and performance optimization
Selecting the appropriate glucocorticoid for specific indications (dexamethasone for brain oedema, betamethasone for antenatal lung maturation, hydrocortisone for adrenal replacement), representing an important application area for the Steroid Conversion in professional and analytical contexts where accurate steroid conversion calculations directly support informed decision-making, strategic planning, and performance optimization
Educating patients about the relative potency of their steroid medications and the rationale for dose adjustments, representing an important application area for the Steroid Conversion in professional and analytical contexts where accurate steroid conversion calculations directly support informed decision-making, strategic planning, and performance optimization
Adrenal replacement therapy
{'title': 'Adrenal replacement therapy', 'body': 'For physiological cortisol replacement in adrenal insufficiency, hydrocortisone 15-25 mg/day in 2-3 divided doses (mimicking diurnal rhythm with largest dose on waking) is recommended. Prednisolone 3-5 mg/day (morning only) is an alternative for better compliance. Dexamethasone is generally avoided for replacement due to its very long duration, difficulty titrating to physiological levels, and risk of Cushing syndrome. Mineralocorticoid replacement with fludrocortisone is always required in primary AI regardless of glucocorticoid choice.'}
Dexamethasone for preterm labour
{'title': 'Dexamethasone for preterm labour', 'body': 'Antenatal betamethasone or dexamethasone (12 mg IM x 2 doses 24 hours apart, or 6 mg IM x 4 doses 12 hours apart) is given to mothers at 23-34 weeks gestation to accelerate fetal lung maturity and reduce neonatal respiratory distress syndrome. The choice of betamethasone over dexamethasone for antenatal use is recommended by most guidelines as it contains no preservative and has better RCT evidence for neonatal outcomes.'}
Glucocorticoid tapering to avoid adrenal crisis
{'title': 'Glucocorticoid tapering to avoid adrenal crisis', 'body': 'Patients who have received more than 5 mg prednisolone (or equivalent) for more than 4 weeks are at risk of HPA axis suppression. Rapid cessation can cause adrenal crisis. Tapering protocols vary by dose and duration but typically reduce by 10-25% every 1-2 weeks. Very slow tapering below physiological replacement doses (prednisolone <5 mg, hydrocortisone <20 mg) may be required until HPA axis recovery is confirmed by SST.'}
COVID-19 and dexamethasone
{'title': 'COVID-19 and dexamethasone', 'body': 'The RECOVERY trial (2020) demonstrated that dexamethasone 6 mg/day for 10 days significantly reduced mortality in hospitalised COVID-19 patients requiring oxygen or ventilation. The equivalent prednisolone dose is 40 mg/day, and methylprednisolone 32 mg/day. Some centres use alternative agents at equivalent doses when dexamethasone is unavailable.'}
| Drug | Equivalent dose (mg) | Glucocorticoid potency | Mineralocorticoid potency | Duration of action |
|---|---|---|---|---|
| Hydrocortisone | 20 | 1x | +++ | Short (8-12h) |
| Prednisolone | 5 | 4x | + | Intermediate (12-36h) |
| Prednisone | 5 | 4x | + | Intermediate (12-36h) |
| Methylprednisolone | 4 | 5x | +/- | Intermediate (12-36h) |
| Triamcinolone | 4 | 5x | 0 | Intermediate |
| Dexamethasone | 0.75 | 25x | 0 | Long (36-54h) |
| Betamethasone | 0.75 | 25x | 0 | Long (36-54h) |
| Fludrocortisone | N/A (mineralocorticoid) | 10x | ++++ | Long |
Why do different glucocorticoids have different potencies?
Glucocorticoid potency is determined by receptor binding affinity, bioavailability after oral administration, protein binding, metabolic half-life, and tissue distribution. Dexamethasone's fluorine substituent markedly increases its glucocorticoid receptor affinity and resistance to metabolic inactivation, making it much more potent per mg than hydrocortisone. Bioavailability also varies — methylprednisolone has near-complete oral bioavailability, while prednisone requires hepatic conversion to prednisolone.
What is mineralocorticoid activity and why does it matter?
Mineralocorticoid activity refers to the ability of a glucocorticoid to act on aldosterone receptors in the kidney, causing sodium and water retention and potassium excretion. Hydrocortisone has the highest mineralocorticoid activity among systemic glucocorticoids (about 1/500 that of aldosterone but still clinically relevant). Prednisolone has weak mineralocorticoid activity; dexamethasone and betamethasone have virtually none. Patients needing mineralocorticoid replacement (primary adrenal insufficiency) must receive fludrocortisone regardless of their glucocorticoid choice.
Is prednisone the same as prednisolone?
Prednisone is a prodrug that is converted in the liver to prednisolone (its active form). In patients with severe hepatic disease, this conversion is impaired, making prednisolone the preferred agent. For practical purposes, 5 mg prednisone equals 5 mg prednisolone in patients with normal hepatic function, as both are included in the standard equivalence table at equal potency.
Why is dexamethasone used for cerebral oedema and nausea prophylaxis?
Dexamethasone's high potency, long duration of action, negligible mineralocorticoid activity (reducing fluid retention risk), and excellent CNS penetration make it ideal for treating peritumoral cerebral oedema. Its prolonged anti-inflammatory effect with once or twice-daily dosing is also advantageous for PONV prophylaxis. A single dose of dexamethasone 4-8 mg reduces PONV incidence by 25-30% without significant immunosuppression risk.
How does inhaled corticosteroid dose relate to systemic equivalences?
Inhaled corticosteroid (ICS) doses cannot be directly converted using the systemic equivalence table because topical potency, inhalation device efficiency, particle size, and systemic bioavailability all differ dramatically from oral glucocorticoids. Approximate ICS to systemic equivalences exist (e.g., fluticasone propionate 1000 mcg/day inhaled is approximately equivalent to prednisolone 5-10 mg/day systemically in terms of HPA suppression), but these are estimates and vary between individuals.
Can the conversion table be used for topical and intra-articular steroids?
The systemic equivalence table applies to systemically administered glucocorticoids (oral, IV, IM). Topical and intra-articular preparations have very different local and systemic exposure profiles. However, clinically significant systemic absorption from topical steroids (particularly high-potency agents on large skin areas or under occlusion) and intra-articular injections can suppress the HPA axis, and the systemic equivalent exposure should be estimated when managing patients at risk.
What is the dose equivalence for budesonide and beclomethasone?
These ICS agents are not included in the standard systemic equivalence table because they are primarily designed for topical pulmonary or gastrointestinal use. Oral budesonide (for IBD) has approximately 9-fold lower systemic bioavailability than prednisolone due to extensive first-pass hepatic metabolism, which is why it causes less systemic side effects at equivalent local anti-inflammatory doses.
How does steroid dosing change during critical illness?
In septic shock or critical illness, physiological cortisol requirements can increase from a normal 15-25 mg/day equivalent to 200-400 mg hydrocortisone-equivalent per day. Stress-dose hydrocortisone (200 mg/day as continuous infusion or 50 mg 6-hourly) is recommended in refractory septic shock despite adequate volume resuscitation and vasopressors. The conversion table equivalences still apply for calculating stress-dose equivalents of other agents.
プロのヒント
A useful mental rule: dexamethasone is approximately 7 times more potent than prednisolone per milligram (0.75 mg dexamethasone = 5 mg prednisolone, so 1 mg dexamethasone ≈ 6.7 mg prednisolone). This relationship is the basis for understanding why the RECOVERY trial's dexamethasone 6 mg/day was equivalent to approximately prednisolone 40 mg/day in anti-inflammatory effect.
ご存知でしたか？
Cortisone — the first glucocorticoid used therapeutically — was synthesised from bile acids by Edward Kendall and Philip Hench, who shared the 1950 Nobel Prize in Medicine for this discovery. Their first successful use was to treat a woman with severe rheumatoid arthritis who had been bedridden for years — she walked unassisted within days of starting cortisone injections, describing it as a 'miracle'. The excitement of those first days led to decades of overuse before the severe side effects of long-term glucocorticoid therapy were fully appreciated.
参考文献
- ›RECOVERY Collaborative Group. Dexamethasone in hospitalised patients with COVID-19. NEJM 2021
- ›Bornstein SR et al. Diagnosis and Treatment of Primary Adrenal Insufficiency (Endocrine Society 2016)
- ›British National Formulary — Corticosteroids: Equivalent doses
- ›Prete A et al. Approach to the Patient: Glucocorticoid Replacement in Adrenal Insufficiency. J Clin Endocrinol Metab 2021