When to Give Fludrocortisone Acetate 0.1 mg Oral Tablet
Fludrocortisone acetate 0.1 mg should be given daily to all patients with confirmed primary adrenal insufficiency (Addison's disease) who have aldosterone deficiency, typically in combination with glucocorticoid replacement therapy. 1
Primary Indications
Primary Adrenal Insufficiency (Addison's Disease)
- Standard dosing: 0.1 mg daily is the typical dose, though the range is 0.05-0.2 mg daily 2
- Must be combined with glucocorticoid therapy (hydrocortisone 10-30 mg daily or cortisone 10-37.5 mg daily in divided doses) 2
- The combination provides substitution therapy that approximates normal adrenal activity 2
- Timing: Preferably administered once daily in the morning, as aldosterone follows a circadian rhythm similar to cortisol 1
Salt-Losing Adrenogenital Syndrome
- Dosing: 0.1-0.2 mg daily 2
- Higher doses may be needed in newborns and children compared to adults due to lower mineralocorticoid sensitivity 1
Clinical Assessment for Initiation
Start fludrocortisone when patients demonstrate:
- Confirmed aldosterone deficiency in the setting of primary adrenal insufficiency 1
- Clinical signs: salt craving, postural hypotension, or orthostatic symptoms 1
- Laboratory findings: electrolyte abnormalities (hyponatremia, hyperkalemia) 1
Monitoring and Dose Adjustment
Clinical indicators of appropriate dosing:
- General well-being maintained
- Electrolytes within normal range
- Normal blood pressure without postural hypotension
- Plasma renin activity in the upper reference range 1
Signs requiring dose reduction:
Signs requiring dose increase:
- Persistent salt craving
- Postural hypotension or light-headedness
- Hot climate or excessive sweating conditions → temporary 50-100% dose increase 1
Important Considerations
Glucocorticoid Interactions
- Patients on prednisolone may require more fludrocortisone than those on hydrocortisone because prednisolone has less mineralocorticoid activity 1
- Dexamethasone has no mineralocorticoid activity, necessitating full fludrocortisone replacement 1
Drug and Food Interactions to Avoid
- Licorice and grapefruit juice potentiate mineralocorticoid effects and should be avoided 1
- Phenytoin increases fludrocortisone metabolism, requiring higher replacement doses 1
Special Situations
- Adrenal crisis: Fludrocortisone is NOT required acutely when high-dose hydrocortisone (≥100 mg) is given, as hydrocortisone provides sufficient mineralocorticoid activity at stress doses 3
- Start or restart fludrocortisone 0.05-0.1 mg daily once transitioning from stress dosing to maintenance therapy 3
Common Pitfall
Do not use plasma ACTH levels to guide fludrocortisone dosing—this is a mineralocorticoid replacement issue, not a glucocorticoid one. ACTH monitoring is inappropriate even for glucocorticoid dosing as it leads to over-replacement 1.