Aldosterone is a mineralocorticoid produced in the adrenal cortex. It represents an important link in the renin-angiotensin-aldosterone system (RAAS), which helps regulate blood pressure and salt balance. Increased renin is produced when a lack of sodium in the blood or hypovolemia (decreased blood volume) is determined by the receptors. Renin in turn stimulates the activation of angiotensinogen to angiotensin I, which is then converted to angiotensin II by other hormones. Angiotensin II leads to vasoconstriction (narrowing of blood vessels) and thus to an increase in blood pressure. In addition, it leads to a release of aldosterone, which results in sodium and water reabsorption.
The procedure
Material needed
- Blood serum
- 24 h urine
Preparation of the patient
- Collection of blood sample after lying position for at least three hours.
- If possible, the diuretic (drug for drainage) spironolactone – an aldosterone antagonist – should be discontinued three weeks before the examination!
- If possible, the following medications should be discontinued one week before the examination:
- Antihypertensives (antihypertensives).
- Antidepressants
- Diuretics (dehydrating drugs)
- Gentamycin (antibiotic)
- Hormones: corticoids (such as cortisone); estrogens (female sex hormones).
- Potassium
Disruptive factors
- Process sample immediately
Normal values adults – blood serum
| Body position | Normal value in ng/l |
| Lying down | 12-150 |
| Standing | 70-350 |
Normal values children – blood serum
| Age | Normal value in ng/l |
| Newborn | 1.200-8.500 |
| 11 days – 1 year | 320-1.278 |
| < 15 years | 73-425 |
Standard values – collected urine
| Normal value in μg/24h | 2-30 |
Indications
- Suspected renal cause of hypertension (high blood pressure).
- Suspected primary hyperaldosteronism (Conn’s disease)-disease leading to elevated serum aldosterone levels and decreased serum renin levels; often caused by adenomas (benign tumors)
- Suspected aldosterone dysfunction.
Interpretation
Interpretation of increased values
- Adrenogenital syndrome (AGS) – autosomal recessive inherited metabolic disorder characterized by disorders of hormone synthesis in the adrenal cortex. These disorders lead to a deficiency of aldosterone and cortisol.
- Bartter syndrome – genetic disorder that leads to hypokalemia (potassium deficiency).
- Chronic renal insufficiency (kidney weakness).
- Cushing’s syndrome – disease caused by an excess of glucocorticoids.
- Essential hypertension (high blood pressure).
- Renal artery stenosis – narrowing of the artery supplying the kidney.
- Panarteriits nodosa – systemic disease affecting the arteries, which is caused by an excessive immune response.
- Primary hyperaldosteronism (Conn’s disease) – disease resulting in elevated serum aldosterone levels and decreased serum renin levels; often caused by adenomas (benign tumor).
- Secondary hyperaldosteronism (renovascular hypertension, renin-secreting tumors, chronic renal failure).
- Postoperative – physiological change
- Pseudo-Bartter syndrome – hypokalemia (potassium deficiency) caused by diuretic or laxative abuse (draining -/laxative drugs).
- Pregnancy – physiological change
- Tumors that secrete renin, such as renal cell carcinoma (kidney cell cancer) or bronchial carcinoma (lung cancer)
- Water retention in the tissues such as edema or ascites.
Interpretation of decreased values
- Aldosterone synthesis disorder
- Primary hypoaldosteronism (Addison’s disease)
- Secondary hypoaldosteronism due to pituitary insufficiency (inability of the pituitary gland to produce sufficient hormones) or hyporeninemia (due to low renin serum levels).
Other indications
- When the blood sample is taken in a sitting position, the values can be increased up to fourfold
