What is the recommended dose of Fludocortisone for a patient with Primary Chronic Adrenal Insufficiency, such as Addison's disease?

Fludocortisone Dosing in Primary Adrenal Insufficiency

Most patients with primary adrenal insufficiency should take 50-200 µg of fludrocortisone as a single daily morning dose, with children and younger adults sometimes requiring higher doses up to 500 µg daily. 1

Standard Dosing Regimen

• The typical starting dose is 100 µg (0.1 mg) daily, taken as a single morning dose upon awakening. 2
• The FDA-approved dosing range extends from 100 µg three times weekly to 200 µg daily, though most patients require daily dosing for optimal mineralocorticoid replacement. 2
• Younger adults and children often require higher doses (up to 500 µg daily) due to physiological differences in mineralocorticoid sensitivity and higher progesterone levels in the third trimester of pregnancy. 1

Dose Adjustment Algorithm

Increase Fludrocortisone When:

• Orthostatic hypotension persists despite adequate sodium intake - this indicates under-replacement and predisposes to recurrent adrenal crises. 3
• Salt cravings continue despite unrestricted salt consumption - a key clinical indicator of inadequate mineralocorticoid replacement. 3
• Serum sodium is low or potassium is elevated - direct biochemical evidence requiring dose escalation. 3
• Lightheadedness occurs, particularly with position changes - suggests volume depletion from insufficient mineralocorticoid effect. 3

Decrease Fludrocortisone When:

• Essential hypertension develops - reduce the dose but never stop fludrocortisone completely, as complete discontinuation can trigger adrenal crisis. 1, 3
• Peripheral edema appears - indicates over-replacement with excessive sodium retention. 3
• Supine hypertension occurs - requires dose reduction while maintaining some mineralocorticoid coverage. 3

Critical Monitoring Parameters

• Blood pressure should be measured in both supine and standing positions at each visit to detect orthostatic changes suggesting under-replacement or hypertension indicating over-replacement. 3
• Serum electrolytes (sodium and potassium) must be checked at least annually and whenever adjusting doses. 1, 3
• Clinical symptoms including salt cravings, lightheadedness, and peripheral edema provide essential guidance for dose titration. 3
• Weight and overall volume status help assess adequacy of mineralocorticoid replacement. 1

Essential Dietary and Medication Considerations

• Patients must consume salt and salty foods without restriction - unrestricted sodium intake is a critical third component of therapy alongside glucocorticoid and mineralocorticoid replacement. 1, 3
• Avoid potassium-containing salt substitutes marketed as "healthy" alternatives, as these can worsen hyperkalemia. 1, 3
• Avoid liquorice and grapefruit juice - both potentiate mineralocorticoid effects and may necessitate dose reduction. 1, 3
• Avoid diuretics, acetazolamide, carbenoxolone, and NSAIDs - these medications interact with fludrocortisone and can unpredictably alter its effects. 3
• Drospirenone-containing contraceptives may require higher fludrocortisone doses due to anti-mineralocorticoid effects. 3

Common Pitfalls to Avoid

• Never stop fludrocortisone completely when hypertension develops - instead, reduce the daily dose to the lowest effective amount, as complete discontinuation can precipitate life-threatening adrenal crisis. 1, 3
• Under-replacement is common and dangerous - it predisposes patients to recurrent adrenal crises, so err on the side of adequate replacement when clinical uncertainty exists. 3
• Do not attempt alternate-day dosing - fludrocortisone must be administered daily because mineralocorticoids are vital for continuous blood pressure and electrolyte homeostasis. 4
• Abrupt discontinuation triggers adrenal crisis characterized by hypotension, hyponatremia, hyperkalemia, and potentially fatal cardiovascular collapse. 3

Special Populations

• Pregnancy, particularly the third trimester, may require increased fludrocortisone doses due to progesterone's anti-mineralocorticoid effects. 1, 3
• Children and younger adults frequently need doses at the higher end of the range or even up to 500 µg daily. 1
• Salt-losing adrenogenital syndrome requires 100-200 µg daily according to FDA labeling. 2

Integration with Glucocorticoid Therapy

• Fludrocortisone is preferably administered in conjunction with hydrocortisone (10-30 mg daily in divided doses) or cortisone acetate (10-37.5 mg daily in divided doses) to approximate normal adrenal activity. 2, 5
• The combination provides complete substitution therapy for both glucocorticoid and mineralocorticoid deficiencies in primary adrenal insufficiency. 2, 6