Initiate Fludrocortisone for Aldosterone Deficiency with Specific Starting Dose
STEP 1 — Gather Information
Confirm primary adrenal insufficiency (PAI) diagnosis; measure morning plasma aldosterone and renin to demonstrate low aldosterone with elevated renin; assess for symptoms of mineralocorticoid deficiency (salt craving, postural hypotension, hyponatremia, hyperkalemia); ensure no concurrent salt restriction; review blood pressure for hypertension.
STEP 2 — Rule In / Rule Out
Is aldosterone deficiency confirmed (low aldosterone with inappropriately normal or high renin)?
- Yes → Proceed to STEP 3.
- No → Do not initiate fludrocortisone; reassess etiology.
STEP 3 — Classify or Stratify
Is the patient an adult (≥18 years)?
- Adult → Use starting dose 50–100 µg daily.
- Pediatric → Refer to pediatric dosing (e.g., 100 µg/d for children, infant salt supplements).
STEP 4 — Decide
Initiate fludrocortisone at 50–100 µg once daily in the morning; counsel patient not to restrict salt intake; schedule follow‑up in 2–4 weeks to assess symptoms, blood pressure, and electrolytes.
Clinical Guardrails / Mimics / Pitfalls
Avoid in patients with uncontrolled hypertension or edema; monitor for signs of over‑replacement (hypertension, supine edema, hypokalemia); do not combine with licorice, grapefruit juice, or potent CYP3A4 inducers that may alter fludrocortisone metabolism; fludrocortisone is not indicated for secondary adrenal insufficiency; if hypertension develops, reduce dose before adding antihypertensives.
Concrete Clinical Example
A 34‑year‑old woman with newly diagnosed PAI (low cortisol, high ACTH) has serum aldosterone 2 ng/dL (low), renin 45 mIU/L (high), reports salt craving and occasional light‑headedness on standing. She is normotensive. Start fludrocortisone 100 µg daily, advise liberal salt intake, and re‑evaluate in 3 weeks.
Source: Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2016, DOI:10.1210/jc.2015-1710
TODO: consider adding scripts/calc.py for the enda-fludrocortisone-aldosterone-deficiency calculator