Glucocorticoid Equivalence Converter

⚒ Clinical Context & Pearls

Steroid conversions are not strictly linear. While standard equivalent tables provide a mathematical baseline, patient response varies based on receptor affinity, protein binding, and underlying organ dysfunction.

The 100-25-4 Equivalence Mnemonic

A simple, commonly taught bedside mnemonic for estimating standard potency ratios is 100 = 25 x 4. This is highly useful during emergency resuscitation:

• 100 mg of Hydrocortisone (the physiological baseline) is roughly equivalent to...
• 25 mg of Prednisolone, which is roughly equivalent to...
• 4 mg of Dexamethasone. (Note: Strict pharmacological math places this closer to 3.75 mg, but 4 mg is the standard clinical approximation for this rule.)

1. Mineralocorticoid Activity (Sodium Retention)

The most dangerous error in steroid conversion is ignoring mineralocorticoid activity during critical illness (e.g., septic shock or Addisonian crisis).

• Hydrocortisone has a 1:1 ratio of glucocorticoid to mineralocorticoid effect. It is the drug of choice for primary adrenal insufficiency.
• Dexamethasone and Methylprednisolone have practically zero mineralocorticoid activity. If you switch a patient from Hydrocortisone to Dexamethasone, their blood pressure may collapse due to sodium wasting unless Fludrocortisone is added.

2. Biologic Half-Life & Dosing Frequency

You cannot convert a long-acting steroid to a short-acting steroid and maintain the same dosing frequency.

• Short-acting (8-12 hours): Hydrocortisone, Cortisone. Must be dosed BID to QID.
• Intermediate-acting (12-36 hours): Prednisolone, Methylprednisolone, Deflazacort. Can be dosed OD or BID.
• Long-acting (36-72 hours): Dexamethasone, Betamethasone. Dosed OD.

3. HPA Axis Suppression & Tapering

Any patient on a dose greater than the physiological equivalent of 5 mg Prednisolone per day for more than 3 weeks must be assumed to have Hypothalamic-Pituitary-Adrenal (HPA) axis suppression.

• Abrupt cessation will cause acute secondary adrenal insufficiency.
• Tapering should be dictated by the underlying disease activity initially, but once below 7.5 mg of Prednisolone equivalent, the taper must slow significantly (e.g., 1 mg drop every 1-2 weeks) to allow the adrenal glands to recover physiological cortisol production.