II. Definitions
- Aldosterone
- Aldosterone is a key Mineralocorticoid that triggers renal retention of Sodium (and water) and Potassium excretion
- Steroid Hormone synthesized in the zona glomerulosa of the Adrenal Cortex, with release triggered by Angiotensin 2
- Mineralocorticoid
- Class of Corticosteroids regulating Sodium and Water Homeostasis, primarily the retention of Sodium (and water)
- Aldosterone is the key Mineralocorticoid (although agents have Mineralocorticoid activity such as Progesterone)
- Fludrocortisone (Florinef) is a synthetic agent with Mineralocorticoid activity
III. Physiology
- See Sodium and Water Homeostasis
- Aldosterone is a key Mineralocorticoid
- Triggers renal retention of Sodium (and water)
- Ions exchanged for Sodium ion retention
- Potassium (increased Potassium excretion)
- Hydrogen Ion (alkalosis)
- Aldosterone is a steroid Hormone synthesized in the zona glomerulosa of the Adrenal Cortex
- Aldosterone levels represent only 1% of Glucocorticoid levels (esp. Cortisol)
- Modifying factors
- Release is stimulated primarily by Angiotensin 2, but also by ACTH and Hyperkalemia
- Atrial natriuretic factor inhibits Aldosterone release
- Mineralocorticoids are inactivated by 11-beta hydroxysteroid dehydrogenase 2
- Chronic Licorice intake inhibits this enzyme and may result in Secondary Hyperaldosteronism
IV. Pathophysiology
V. Labs
- Typically measured with plasma renin activity (PRA) to obtain a morning Aldosterone to PRA ratio
- Serum Aldosterone (radioimmunoassay)
- Normal Morning level in resting, seated adults: 5 to 30 ng/dl (140 to 830 pmol/L)
- Miscellaneous effects on levels
- Lower levels in black patients
- Levels are highest in the morning and lowest in evening
VI. Causes: Increased Serum Aldosterone
- See Hyperaldosteronism
- Primary Aldosteronism
-
Secondary Hyperaldosteronism
- Renal Artery Stenosis
- Malignant Hypertension
- Edematous States with intravascular volume depletion (e.g. Heart Failure, Cirrhosis)
- Medications (Aldosterone Antagonists, Progesterone)
- Hyperkalemia
- Women in Luteal Phase of Menstrual Cycle
- Pregnancy
- Levels may be 10 fold higher in third trimester than in non-pregnant patients
- High licorice consumption
VII. Causes: Decreased Serum Aldosterone
- 11-beta Hydroxylase deficiency
- 17-alpha-hydroxylase deficiency
- Cushing Syndrome
- Primary Adrenal Insufficiency
- Liddle's Syndrome
- Diabetic Nephropathy
- Ectopic ACTH Syndrome
VIII. Resources
- Mineralocorticoid (wikipedia)
IX. References
- Stowasser in Lacroix (2021) Assays of Renin-Angiotensin-Aldosterone system in adrenal disease, UpToDate, accessed 2/26/2022