II. Definitions

  1. Aldosterone
    1. Aldosterone is a key Mineralocorticoid that triggers renal retention of Sodium (and water) and Potassium excretion
    2. Steroid Hormone synthesized in the zona glomerulosa of the Adrenal Cortex, with release triggered by Angiotensin 2
  2. Mineralocorticoid
    1. Class of Corticosteroids regulating Sodium and Water Homeostasis, primarily the retention of Sodium (and water)
    2. Aldosterone is the key Mineralocorticoid (although agents have Mineralocorticoid activity such as Progesterone)
    3. Fludrocortisone (Florinef) is a synthetic agent with Mineralocorticoid activity

III. Physiology

  1. See Sodium and Water Homeostasis
  2. Aldosterone is a key Mineralocorticoid
    1. Triggers renal retention of Sodium (and water)
    2. Ions exchanged for Sodium ion retention
      1. Potassium (increased Potassium excretion)
      2. Hydrogen Ion (alkalosis)
  3. Aldosterone is a steroid Hormone synthesized in the zona glomerulosa of the Adrenal Cortex
    1. Aldosterone levels represent only 1% of Glucocorticoid levels (esp. Cortisol)
  4. Modifying factors
    1. Release is stimulated primarily by Angiotensin 2, but also by ACTH and Hyperkalemia
    2. Atrial natriuretic factor inhibits Aldosterone release
  5. Mineralocorticoids are inactivated by 11-beta hydroxysteroid dehydrogenase 2
    1. Chronic Licorice intake inhibits this enzyme and may result in Secondary Hyperaldosteronism

IV. Pathophysiology

V. Labs

  1. Typically measured with plasma renin activity (PRA) to obtain a morning Aldosterone to PRA ratio
    1. See Hyperaldosteronism
  2. Serum Aldosterone (radioimmunoassay)
    1. Normal Morning level in resting, seated adults: 5 to 30 ng/dl (140 to 830 pmol/L)
  3. Miscellaneous effects on levels
    1. Lower levels in black patients
    2. Levels are highest in the morning and lowest in evening

VI. Causes: Increased Serum Aldosterone

  1. See Hyperaldosteronism
  2. Primary Aldosteronism
  3. Secondary Hyperaldosteronism
    1. Renal Artery Stenosis
    2. Malignant Hypertension
    3. Edematous States with intravascular volume depletion (e.g. Heart Failure, Cirrhosis)
    4. Medications (Aldosterone Antagonists, Progesterone)
  4. Hyperkalemia
  5. Women in Luteal Phase of Menstrual Cycle
  6. Pregnancy
    1. Levels may be 10 fold higher in third trimester than in non-pregnant patients
  7. High licorice consumption

VII. Causes: Decreased Serum Aldosterone

  1. 11-beta Hydroxylase deficiency
  2. 17-alpha-hydroxylase deficiency
  3. Cushing Syndrome
  4. Primary Adrenal Insufficiency
  5. Liddle's Syndrome
  6. Diabetic Nephropathy
  7. Ectopic ACTH Syndrome

VIII. Resources

IX. References

  1. Stowasser in Lacroix (2021) Assays of Renin-Angiotensin-Aldosterone system in adrenal disease, UpToDate, accessed 2/26/2022

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