Aldosterone — serum / plasma
Aldosterone rises markedly during pregnancy because of renin–angiotensin–aldosterone activation needed for maternal plasma volume expansion. Levels may increase 5–10× above nonpregnant values by mid- to late gestation.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| ng/dL | 2 – 9 | 6 – 104 | 9 – 104 | 15 – 101 |
| pmol/L | 56 – 250 | 166 – 2885 | 250 – 2885 | 416 – 2801 |
Causes of elevated aldosterone
- Physiologic (normal pregnancy)
- Increased renin and angiotensin II
- Expanded plasma volume
- Primary hyperaldosteronism
- Aldosterone-producing adenoma (Conn syndrome)
- Bilateral adrenal hyperplasia
- Familial hyperaldosteronism (types I–III)
- Secondary hyperaldosteronism
- Renal artery stenosis
- Renin-secreting tumors
- Congestive heart failure
- Cirrhosis with ascites
- Nephrotic syndrome
- Pregnancy-specific considerations
- Preeclampsia (may modify RAAS activation)
- Hyperemesis / dehydration → ↑ renin → ↑ aldosterone
Causes of low aldosterone
- Adrenal insufficiency
- Addison disease
- Autoimmune adrenalitis
- Adrenal hemorrhage or infarction
- Hyporeninemic hypoaldosteronism
- Diabetic kidney disease
- Chronic kidney disease
- NSAIDs
- Heparin (pregnancy-relevant)
- Medications
- ACE inhibitors / ARBs (inadvertent early exposure)
- Renin inhibitors
- Heparin
- Pregnancy-specific interpretation
- Low aldosterone is abnormal in pregnancy and suggests adrenal insufficiency or medication effect.
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009;114:1326–31.
- Wallach J. Interpretation of Diagnostic Tests, 8th ed.
- Fischbach FT, Dunning MB. A Manual of Laboratory and Diagnostic Tests, 7th ed.